Normal values of aortic dimensions, distensibility, and pulse wave velocity in children and young adults: a cross-sectional study

  • Inga Voges1Email author,

    Affiliated with

    • Michael Jerosch-Herold3Email author,

      Affiliated with

      • Jürgen Hedderich2,

        Affiliated with

        • Eileen Pardun1,

          Affiliated with

          • Christopher Hart1,

            Affiliated with

            • Dominik Daniel Gabbert1,

              Affiliated with

              • Jan Hinnerk Hansen1,

                Affiliated with

                • Colin Petko1,

                  Affiliated with

                  • Hans-Heiner Kramer1Email author and

                    Affiliated with

                    • Carsten Rickers1Email author

                      Affiliated with

                      Journal of Cardiovascular Magnetic Resonance201214:77

                      DOI: 10.1186/1532-429X-14-77

                      Received: 9 November 2011

                      Accepted: 16 October 2012

                      Published: 14 November 2012

                      Abstract

                      Background

                      Aortic enlargement and impaired bioelasticity are of interest in several cardiac and non-cardiac diseases as they can lead to cardiovascular complications. Cardiovascular magnetic resonance (CMR) is increasingly accepted as a noninvasive tool in cardiovascular evaluation. Assessment of aortic anatomy and bioelasticity, namely aortic distensibility and pulse wave velocity (PWV), by CMR is accurate and reproducible and could help to identify anatomical and bioelastic abnormalities of the aorta. However, normal CMR values for healthy children and young adults are lacking.

                      Methods

                      Seventy-one heart-healthy subjects (age 16.4 ± 7.6 years, range 2.3 - 28.3 years) were examined using a 3.0 Tesla CMR scanner. Aortic cross-sectional areas and aortic distensibility were measured at four positions of the ascending and descending thoracic aorta. PWV was assessed from aortic blood flow velocity measurements in a aortic segment between the ascending aorta and the proximal descending aorta. The Lambda-Mu-Sigma (LMS) method was used to obtain percentile curves for aortic cross-sectional areas, aortic distensibility and PWV according to age.

                      Results

                      Aortic areas, PWV and aortic distensibility (aortic cross-sectional areas: r = 0.8 to 0.9, p < 0.001; PWV: r = 0.25 to 0.32, p = 0.047 to 0.009; aortic distensibility r = -0.43 to -0.62, p < 0.001) correlated with height, weight, body surface area, and age. There were no significant sex differences.

                      Conclusions

                      This study provides percentile curves for cross-sectional areas, distensibility and pulse wave velocity of the thoracic aorta in children and young adolescents between their 3rd and 29th year of life. These data may serve as a reference for the detection of pathological changes of the aorta in cardiovascular disease.

                      Background

                      The thoracic aorta plays an important role in the cardiovascular system. It’s elastic buffering capacity transforms the pulsatile effect caused by ventricular ejection into a continuous blood flow [1, 2]. In children and young adults several cardiac and non-cardiac diseases manifest themselves by aortic enlargement and impaired aortic bioelastic function [36]. These changes may be of clinical relevance as they can lead to cardiovascular complications such as left ventricular dysfunction [7], aneurysm formation, atherosclerosis, myocardial infarction and stroke [810] in later life.

                      Aortic distensibility and aortic pulse wave velocity (PWV) are two parameters closely related to the bioelastic function of the aorta and serve as pathogenic markers in cardiovascular disease [11]. Quantification of aortic distensibility and PWV by cardiovascular magnetic resonance (CMR) has been shown to be accurate and reproducible and could help in identifying early cardiovascular disease in asymptomatic patients [1, 12, 13].

                      However, reference ranges from childhood to adulthood are lacking. Therefore we sought to establish CMR normal ranges of aortic distensibility and aortic PWV as well as of aortic cross-sectional areas in heart-healthy children and young adults.

                      Methods

                      Study population

                      71 children and young adults aged 2.3 - 28.3 years underwent a CMR study for the assessment of aortic dimensions, distensibilty and PWV. Table 1 shows the sex and age distribution of the total study group.
                      Table 1

                      Sex and age distribution of the study group

                       

                      Age classes (years)

                      Total

                         

                      -5

                      5 - 10

                      10-15

                      15-20

                      20-25

                      25-30

                       

                      Sex

                      male

                      n

                      2

                      10

                      7

                      2

                      6

                      3

                      30

                      %

                      6.7%

                      33.3%

                      23.3%

                      6.7%

                      20.0%

                      10.0%

                      100.0%

                      female

                      n

                      2

                      7

                      7

                      6

                      11

                      8

                      41

                      %

                      4.9%

                      17.1%

                      17.1%

                      14.6%

                      26.8%

                      19.5%

                      100.0%

                      Total study group

                      n

                      4

                      17

                      14

                      8

                      17

                      11

                      71

                        

                      %

                      5.6%

                      23.9%

                      19.7%

                      11.3%

                      23.9%

                      15.5%

                      100.0%

                      The study participants were recruited among medical students and healthy children of hospital staff. Five children were recruited from the department of pediatric neurology. They underwent diagnostic magnetic resonance imaging (MRI) of the central nervous system (CNS) because of psychomotor retardation and epilepsy. Immediately after CNS MRI, non-contrast enhanced CMR was performed. All study subjects were free from cardiovascular disease. During the study, heart rate, respiratory motion, oxygen saturation and non-invasive blood pressure were monitored.

                      The study protocol was approved by the local research ethics committee and conformed to the principles outlined in the Declaration of Helsinki. Written informed consent was obtained from participants older than 17 years and all persons responsible for care and custody of the child.

                      Image acquisition

                      All CMR studies were performed with a 3.0 Tesla CMR scanner (Achieva 3.0 T, Philips Medical Systems, Netherlands) using a phased-array coil for cardiac imaging (SENSE™ Cardiac coil, Philips Medical Systems, Netherlands).

                      Gradient echo cine CMR with retrospective gating was applied to assess aortic cross-sectional areas, which were used to describe the normal dimensions of the aorta and for distensibility calculation. We collected axial and coronal stacks of parallel, contiguous, views perpendicular to the aortic axis. The scan parameters were as follows: 280 × 224 mm, voxel size (read-, phase-encoding, and slice directions) 1.88 × 1.94 × 6 mm, TR/TE = 4.4/2.5 ms, 25 cardiac phases, no inter-slice gap, non-breath-hold, number of repetitions: 2, scan duration: 3-6 min.

                      Phase-contrast cine CMR was performed to evaluate aortic PWV and to quantify aortic flow. PWV was assessed in a segment including the ascending aorta, the aortic arch and the proximal descending aorta up to the level of the pulmonary artery bifurcation (Figure 1). The slice plane intersected the ascending aorta at the sinutubular level, and the proximal descending aorta, both at an approximately right angle. Imaging parameters were as follows: FOV 270 × 270 mm, voxel size 1.64 × 1.4 × 7 mm, TR/TE = 4.4/2.7 ms, 40 cardiac phases, velocity encoding = 200 cm/s. To determine the aortic segment length between the two aortic levels, sagittally angulated views of the aortic arch were acquired.
                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Fig1_HTML.jpg
                      Figure 1

                      Aortic PWV, A) Sagittal CMR image that shows the sites where phase contrast cine images were acquired: 1) ascending aorta, 2) descending aorta. The distance between both locations (Δx) was measured along a midline through the aortic arch. B) This graph shows the transit delay (Δt) of the systolic flow curves in the descending relative to the ascending aorta. The transit time (Δt) was determined from the midpoints of the systolic up-slope (ta1 and ta2) on the flow versus time curves. The difference of ta for ascending (ta1) and descending aorta (ta2) locations defined Δt. Pulse wave velocity was estimated as Δx/Δt.

                      Image analysis

                      The images were analyzed with commercially available CMR software (ViewForum release 6.3, Philips Medical Systems, Netherlands).

                      Aortic cross-sectional areas were determined on axial and coronal gradient-cine images at four positions (Figure 2): ascending aorta, transverse aortic arch, aortic isthmus and descending aorta above the diaphragm. All measurements were made at the time of the maximal distension of the aorta. Aortic cross-sectional areas were preferred compared to diameters, because the aorta is not necessarily circular in all segments.
                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Fig2_HTML.jpg
                      Figure 2

                      Cross-sectional aortic areas were assessed from axial and coronal CMR images at four different locations of the thoracic aorta: ascending aorta (1), transverse aortic arch (2), aortic isthmus (3), descending aorta above the diaphragm (4).

                      Aortic distensibility was measured from two-dimensional cine images in the ascending aorta, the transverse aortic arch and at two levels in the descending aorta. The latter were located at the aortic isthmus, and above the diaphragm. Distensibility was calculated [14] as:
                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Equa_HTML.gif

                      Amax and Amin represent the maximal and minimal cross-sectional area of the aorta on cine CMR images, and Pmax and Pmin represent the systolic and diastolic blood pressures (in millimetres of mercury), respectively. Blood pressure was obtained non-invasively using a CMR-compatible patient monitor with sphygmomanometer (Invivo Precess™ 3160, Invivo, Orlando, USA). The sphygmomanometer cuff was placed around the right arm.

                      Aortic flow measurements in the ascending and proximal descending aorta with the CMR phase-contrast technique were used to assess PWV in the aortic arch. Aortic flow versus time curves from phase-contrast cine images were obtained to determine the time delay of the distal flow curve (in the descending aorta), relative to the flow curve in the proximal ascending aorta.

                      The PWV was calculated by the following equation:
                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Equb_HTML.gif
                      whereas Δx is the aortic segment length (in meters) along an intra-luminal center-line between the two measurement locations, measured in a sagittally angulated view of the aortic arch, and Δt is the time delay of the distal flow curve, relative to the proximal flow curve (in seconds, Figure 1). Furthermore mean aortic blood flow and peak systolic velocity were assessed in the ascending aorta (Table 2).
                      Table 2

                      Mean blood flow and maximal flow velocity in the ascending aorta

                      Age classes

                      Mean blood flow (l/min)

                      Maximal velocity (cm/s)

                      -5 years

                      2.8 ± 0.1

                      130.3 ± 2.8

                      5-10 years

                      3.9 ± 0.8

                      131.8 ± 18.3

                      10-15 years

                      4.4 ± 0.9

                      119.7 ± 15.8

                      15-20 years

                      6.1 ± 1.4

                      111.9 ± 23.7

                      20-25 years

                      5.6 ± 1.1

                      121.0 ± 16.0

                      25-30 years

                      5.5 ± 1.2

                      118.5 ± 23.9

                      Data are expressed as mean and standard deviation.

                      Statistical analysis

                      Statistical analysis was performed using MedCalc® Version 11.5.1.0. The quantitative data were expressed as mean and standard deviation. The Mann–Whitney-U test for independent samples was used to compare female and male subgroups. Associations between variables were examined using Spearman’s rank correlation. P values below 0.05 were considered to indicate statistical significance.

                      Reference curves for the aortic measurements were estimated with the Lambda-Mu-Sigma (LMS)-method from Cole and Green [15, 16] for each gender. This method characterizes the age dependent distribution of a target parameter based on a quantile regression fit by three different components: the median (M), the variance (S) and the skewness of the distribution, which is evaluated by an exponential factor (L) from a Box-Cox transformation. L, M and S values can be used to construct reference curves by the following equation:
                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Equc_HTML.gif
                      where zα is the α-quantile in the standard normal distribution, e. g. z0,95 = 1,64. The z-score can be calculated from the LMS values and the measurement value for aortic cross-sectional area, diststensibility or PWV (X):
                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Equd_HTML.gif

                      Results

                      The study group characteristics are presented in Table 3. There were no significant differences between female and male subgroups.
                      Table 3

                      Characteristics of the study population

                      Parameter

                      Total study group

                      Female volunteers

                      Male volunteers

                      P value

                       

                      (n = 71)

                      (n = 41)

                      (n = 30)

                       

                      Age (years)

                      16.4 ± 7.6

                      17.5 ± 7.4

                      14.9 ± 7.7

                      0.18

                      Weight (kg)

                      50.9 ± 21.9

                      51.4 ±19.3

                      50.2 ± 25.1

                      0.73

                      Height (cm)

                      156.6 ± 25.6

                      157.5 ± 23.0

                      156.1 ± 29.1

                      0.86

                      BSA (m2)

                      1.5 ± 0.4

                      1.5 ± 0.4

                      1.5 ± 0.5

                      0.84

                      BMI (kg/m2)

                      19.4 ± 3.5

                      19.7 ± 3.4

                      19.1 ± 3.8

                      0.57

                      SBP (mm Hg)

                      104.9 ± 9.5

                      103.7 ± 9.3

                      106.2 ± 9.7

                      0.48

                      DBP (mm Hg)

                      59.2 ± 11.0

                      58.8 ± 10.9

                      59.4 ± 11.2

                      0.91

                      PP (mm Hg)

                      45.7 ± 8.4

                      44.9 ± 6.6

                      46.8 ± 10.4

                      0.14

                      Data are expressed as mean and standard deviation. P-values are from the Mann–Whitney-U test.

                      BMI, body mass index; BSA, body surface area; DBP, diastolic blood pressure; PP, pulse pressure; SBP, systolic blood pressure.

                      Aortic dimensions

                      Table 4 shows the mean ± SD of the aortic cross-sectional areas for each position classified by gender. No significant differences were found between males and females. All cross-sectional areas correlated well with the age, height, weight, and body surface area (BSA) (Table 5). Gender specific percentile curves between aortic cross-sectional areas and age are shown in Figure 3. Additionally, Tables 6 and 7 shows the L, M and S values relative to age and gender.
                      Table 4

                      Cross-sectional areas, distensibility and PWV of the thoracic aorta by gender

                      Parameter

                      Total study group

                      Female volunteers

                      Male volunteers

                      P value

                       

                      (n = 71)

                      (n = 41)

                      (n = 30)

                       

                      Cross-sectional area (mm2)

                        - Ascending aorta

                      515.3 ± 186.3

                      516.1 ± 171.4

                      514.0 ± 208.3

                      0.68

                        - Aortic arch

                      376.9 ± 148.5

                      383.0 ± 139.1

                      368.2 ± 163.7

                      0.51

                        - Aortic isthmus

                      257.9 ± 89.5

                      250.4 ± 76.2

                      268.3 ± 105.6

                      0.64

                        - Descending aorta above the diaphragm

                      214.2 ± 75.0

                      213.6 ± 68.9

                      214.9 ± 84.0

                      0.81

                      Distensibility (10-3 mm Hg-1)

                        - Ascending aorta

                      8.9 ± 3.6

                      9.2 ± 3.0

                      8.5 ± 4.2

                      0.11

                        - Aortic arch

                      7.7 ± 3.3

                      8.0 ± 3.3

                      7.2 ± 3.4

                      0.2

                        - Aortic isthmus

                      7.4 ± 2.5

                      7.7 ± 2.3

                      7.0 ± 2.7

                      0.11

                        - Descending aorta above the diaphragm

                      8.3 ± 3.0

                      8.8 ± 3.1

                      7.7 ± 2.7

                      0.1

                      PWV (m/s)

                      3.6 ± 0.7

                      3.5 ± 0.6

                      3.7 ± 0.9

                      0.14

                      Data are expressed as mean and standard deviation. P-values are from the Mann–Whitney-U test.

                      PWV, pulse wave velocity.

                      Table 5

                      Correlation of cross-sectional areas with study group characteristics

                       

                      Cross-sectional area (mm2)

                      Parameter

                      Ascending aorta

                      Aortic arch

                      Aortic isthmus

                      Descending aorta above the diaphragm

                      Age (years)

                      0.80†

                      0.80†

                      0.81†

                      0.87†

                      Height (cm)

                      0.84†

                      0.81†

                      0.81†

                      0.82†

                      Weight (kg)

                      0.90†

                      0.85†

                      0.88†

                      0.89†

                      BSA (m2)

                      0.89†

                      0.84†

                      0.87†

                      0.88†

                      Spearman correlation coefficients rho were calculated for the total study group; †p < 0.01.

                      BSA, body surface area.

                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Fig3_HTML.jpg
                      Figure 3

                      Gender-specific reference percentiles for aortic cross-sectional areas at four locations: a) ascending aorta, b) aortic arch, c) aortic isthmus and d) descending aorta above the diaphragm.

                      Table 6

                      LMS parameters for aortic cross-sectional areas relative to age for girls

                       

                      Ascending aorta

                      Aortic arch

                      Aortic isthmus

                      Descending aorta above the diaphragm

                      Age

                      L

                      M

                      S

                      L

                      M

                      S

                      L

                      M

                      S

                        L

                        M

                        S

                      0

                      -0,7876

                      121,1903

                      0,2152

                      -2,1750

                      73,6299

                      0,2114

                      0,1033

                      60,0696

                      0,1621

                      0,9371

                      41,0795

                      0,1398

                      1

                      -0,7876

                      145,9923

                      0,2140

                      -2,1750

                      92,7307

                      0,2089

                      0,1033

                      72,6142

                      0,1617

                      0,9371

                      52,4930

                      0,1398

                      2

                      -0,7876

                      170,7944

                      0,2127

                      -2,1750

                      111,8315

                      0,2064

                      0,1033

                      85,1587

                      0,1613

                      0,9371

                      63,9065

                      0,1398

                      3

                      -0,7876

                      195,5999

                      0,2114

                      -2,1750

                      130,9296

                      0,2039

                      0,1033

                      97,7032

                      0,1609

                      0,9371

                      75,3185

                      0,1398

                      4

                      -0,7876

                      220,4539

                      0,2102

                      -2,1750

                      149,9904

                      0,2013

                      0,1033

                      110,2465

                      0,1605

                      0,9371

                      86,7100

                      0,1398

                      5

                      -0,7876

                      245,4281

                      0,2089

                      -2,1750

                      168,9588

                      0,1988

                      0,1033

                      122,7870

                      0,1601

                      0,9371

                      98,0510

                      0,1398

                      6

                      -0,7876

                      270,5738

                      0,2076

                      -2,1750

                      187,8089

                      0,1963

                      0,1033

                      135,3263

                      0,1597

                      0,9371

                      109,3784

                      0,1398

                      7

                      -0,7876

                      295,9027

                      0,2064

                      -2,1750

                      206,5696

                      0,1938

                      0,1033

                      147,8724

                      0,1593

                      0,9371

                      120,8531

                      0,1398

                      8

                      -0,7876

                      321,3290

                      0,2051

                      -2,1750

                      225,2367

                      0,1913

                      0,1033

                      160,3915

                      0,1588

                      0,9371

                      132,5201

                      0,1398

                      9

                      -0,7876

                      346,5367

                      0,2038

                      -2,1750

                      243,7024

                      0,1887

                      0,1033

                      172,7395

                      0,1584

                      0,9371

                      144,0843

                      0,1398

                      10

                      -0,7876

                      371,3379

                      0,2026

                      -2,1750

                      261,8643

                      0,1862

                      0,1033

                      184,8049

                      0,1580

                      0,9371

                      155,3776

                      0,1398

                      11

                      -0,7876

                      395,6874

                      0,2013

                      -2,1750

                      279,6207

                      0,1837

                      0,1033

                      196,5286

                      0,1576

                      0,9371

                      166,4608

                      0,1398

                      12

                      -0,7876

                      419,5583

                      0,2000

                      -2,1750

                      296,8402

                      0,1812

                      0,1033

                      207,8452

                      0,1572

                      0,9371

                      177,3057

                      0,1398

                      13

                      -0,7876

                      442,8024

                      0,1988

                      -2,1750

                      313,4236

                      0,1787

                      0,1033

                      218,7232

                      0,1568

                      0,9371

                      187,8984

                      0,1398

                      14

                      -0,7876

                      465,1326

                      0,1975

                      -2,1750

                      329,2852

                      0,1761

                      0,1033

                      229,1136

                      0,1564

                      0,9371

                      198,1163

                      0,1398

                      15

                      -0,7876

                      486,2071

                      0,1962

                      -2,1750

                      344,3674

                      0,1736

                      0,1033

                      238,9630

                      0,1560

                      0,9371

                      207,7776

                      0,1398

                      16

                      -0,7876

                      505,7398

                      0,1950

                      -2,1750

                      358,6387

                      0,1711

                      0,1033

                      248,2461

                      0,1556

                      0,9371

                      216,7982

                      0,1398

                      17

                      -0,7876

                      523,5836

                      0,1937

                      -2,1750

                      372,0983

                      0,1686

                      0,1033

                      256,9723

                      0,1552

                      0,9371

                      225,1710

                      0,1398

                      18

                      -0,7876

                      539,7165

                      0,1924

                      -2,1750

                      384,7434

                      0,1661

                      0,1033

                      265,1479

                      0,1547

                      0,9371

                      232,7857

                      0,1398

                      19

                      -0,7876

                      554,1764

                      0,1912

                      -2,1750

                      396,5833

                      0,1635

                      0,1033

                      272,7929

                      0,1543

                      0,9371

                      239,5830

                      0,1398

                      20

                      -0,7876

                      567,1207

                      0,1899

                      -2,1750

                      407,6567

                      0,1610

                      0,1033

                      279,9469

                      0,1539

                      0,9371

                      245,6109

                      0,1398

                      21

                      -0,7876

                      578,7817

                      0,1886

                      -2,1750

                      418,0442

                      0,1585

                      0,1033

                      286,6730

                      0,1535

                      0,9371

                      251,0496

                      0,1398

                      22

                      -0,7876

                      589,4770

                      0,1873

                      -2,1750

                      427,8971

                      0,1560

                      0,1033

                      293,0630

                      0,1531

                      0,9371

                      256,1671

                      0,1398

                      23

                      -0,7876

                      599,5300

                      0,1861

                      -2,1750

                      437,3887

                      0,1534

                      0,1033

                      299,2101

                      0,1527

                      0,9371

                      261,1406

                      0,1398

                      24

                      -0,7876

                      609,3164

                      0,1848

                      -2,1750

                      446,7229

                      0,1509

                      0,1033

                      305,2232

                      0,1523

                      0,9371

                      266,1367

                      0,1398

                      25

                      -0,7876

                      619,1593

                      0,1835

                      -2,1750

                      456,0570

                      0,1484

                      0,1033

                      311,2003

                      0,1518

                      0,9371

                      271,2515

                      0,1398

                      26

                      -0,7876

                      629,1747

                      0,1822

                      -2,1750

                      465,4360

                      0,1459

                      0,1033

                      317,2057

                      0,1514

                      0,9371

                      276,5640

                      0,1398

                      27

                      -0,7876

                      639,3019

                      0,1810

                      -2,1750

                      474,8382

                      0,1433

                      0,1033

                      323,2314

                      0,1510

                      0,9371

                      281,9813

                      0,1398

                      28

                      -0,7876

                      649,4860

                      0,1797

                      -2,1750

                      484,2530

                      0,1408

                      0,1033

                      329,2650

                      0,1506

                      0,9371

                      287,4341

                      0,1398

                      29

                      -0,7876

                      659,6776

                      0,1784

                      -2,1750

                      493,6694

                      0,1383

                      0,1033

                      335,2995

                      0,1502

                      0,9371

                      292,8916

                      0,1398

                      30

                      -0,7876

                      669,8691

                      0,1772

                      -2,1750

                      503,0858

                      0,1358

                      0,1033

                      341,3341

                      0,1498

                      0,9371

                      298,3491

                      0,1398

                      LMS, L = skewness of the distribution, M = median, and S = variance.

                      Table 7

                      LMS parameters for aortic cross-sectional areas relative to age for boys

                       

                      Ascending aorta

                      Aortic arch

                      Aortic isthmus

                      Descending aorta above the diaphragm

                      Age

                      L

                      M

                      S

                      L

                      M

                      S

                      L

                      M

                      S

                        L

                        M

                        S

                      0

                      0,3091

                      91,5360

                      0,1207

                      0,8668

                      80,1737

                      0,1898

                      0,1267

                      53,0050

                      0,1987

                      1,5823

                      44,6080

                      0,1100

                      1

                      0,3091

                      120,6960

                      0,1274

                      0,8668

                      101,7001

                      0,1897

                      0,1267

                      68,7198

                      0,1974

                      1,5823

                      57,0317

                      0,1115

                      2

                      0,3091

                      149,8560

                      0,1341

                      0,8668

                      123,2265

                      0,1895

                      0,1267

                      84,4347

                      0,1960

                      1,5823

                      69,4554

                      0,1129

                      3

                      0,3091

                      179,0160

                      0,1408

                      0,8668

                      144,7529

                      0,1894

                      0,1267

                      100,1495

                      0,1946

                      1,5823

                      81,8791

                      0,1143

                      4

                      0,3091

                      208,1812

                      0,1475

                      0,8668

                      166,2791

                      0,1893

                      0,1267

                      115,8653

                      0,1932

                      1,5823

                      94,3035

                      0,1158

                      5

                      0,3091

                      238,3791

                      0,1542

                      0,8668

                      187,7555

                      0,1891

                      0,1267

                      131,7743

                      0,1918

                      1,5823

                      106,8833

                      0,1172

                      6

                      0,3091

                      272,8715

                      0,1604

                      0,8668

                      208,8732

                      0,1890

                      0,1267

                      148,2790

                      0,1904

                      1,5823

                      119,9057

                      0,1186

                      7

                      0,3091

                      311,2493

                      0,1660

                      0,8668

                      229,2411

                      0,1888

                      0,1267

                      164,9648

                      0,1891

                      1,5823

                      133,0488

                      0,1201

                      8

                      0,3091

                      346,8686

                      0,1707

                      0,8668

                      248,8676

                      0,1887

                      0,1267

                      180,7624

                      0,1877

                      1,5823

                      145,5984

                      0,1215

                      9

                      0,3091

                      380,0230

                      0,1748

                      0,8668

                      268,0557

                      0,1886

                      0,1267

                      195,7825

                      0,1863

                      1,5823

                      157,5124

                      0,1229

                      10

                      0,3091

                      413,8181

                      0,1782

                      0,8668

                      287,2956

                      0,1884

                      0,1267

                      210,6578

                      0,1849

                      1,5823

                      169,3366

                      0,1244

                      11

                      0,3091

                      446,7220

                      0,1812

                      0,8668

                      306,7317

                      0,1883

                      0,1267

                      225,5414

                      0,1835

                      1,5823

                      181,3951

                      0,1258

                      12

                      0,3091

                      476,5703

                      0,1841

                      0,8668

                      326,2205

                      0,1881

                      0,1267

                      240,3324

                      0,1822

                      1,5823

                      193,8192

                      0,1272

                      13

                      0,3091

                      501,7973

                      0,1870

                      0,8668

                      345,4511

                      0,1880

                      0,1267

                      254,6975

                      0,1808

                      1,5823

                      206,4812

                      0,1287

                      14

                      0,3091

                      524,0769

                      0,1902

                      0,8668

                      364,2701

                      0,1879

                      0,1267

                      268,8289

                      0,1794

                      1,5823

                      219,2939

                      0,1301

                      15

                      0,3091

                      546,3695

                      0,1937

                      0,8668

                      382,7610

                      0,1877

                      0,1267

                      282,9653

                      0,1780

                      1,5823

                      232,0152

                      0,1316

                      16

                      0,3091

                      569,8955

                      0,1972

                      0,8668

                      400,9805

                      0,1876

                      0,1267

                      296,9424

                      0,1766

                      1,5823

                      244,3629

                      0,1330

                      17

                      0,3091

                      594,7536

                      0,2003

                      0,8668

                      418,9724

                      0,1875

                      0,1267

                      310,5833

                      0,1752

                      1,5823

                      256,2294

                      0,1344

                      18

                      0,3091

                      620,9611

                      0,2025

                      0,8668

                      436,7805

                      0,1873

                      0,1267

                      323,7094

                      0,1739

                      1,5823

                      267,5155

                      0,1359

                      19

                      0,3091

                      647,1204

                      0,2034

                      0,8668

                      454,4484

                      0,1872

                      0,1267

                      336,0814

                      0,1725

                      1,5823

                      278,0681

                      0,1373

                      20

                      0,3091

                      670,2706

                      0,2030

                      0,8668

                      472,0177

                      0,1871

                      0,1267

                      347,4348

                      0,1711

                      1,5823

                      287,6962

                      0,1387

                      21

                      0,3091

                      690,0681

                      0,2014

                      0,8668

                      489,5219

                      0,1869

                      0,1267

                      357,7775

                      0,1697

                      1,5823

                      296,3958

                      0,1402

                      22

                      0,3091

                      706,8583

                      0,1990

                      0,8668

                      506,9924

                      0,1868

                      0,1267

                      367,1860

                      0,1683

                      1,5823

                      304,2102

                      0,1416

                      23

                      0,3091

                      720,9831

                      0,1960

                      0,8668

                      524,4603

                      0,1866

                      0,1267

                      375,7366

                      0,1670

                      1,5823

                      311,1823

                      0,1430

                      24

                      0,3091

                      732,2902

                      0,1926

                      0,8668

                      541,9124

                      0,1865

                      0,1267

                      383,4824

                      0,1656

                      1,5823

                      317,3075

                      0,1445

                      25

                      0,3091

                      740,4053

                      0,1889

                      0,8668

                      559,3076

                      0,1864

                      0,1267

                      390,6086

                      0,1642

                      1,5823

                      322,5658

                      0,1459

                      26

                      0,3091

                      747,1815

                      0,1849

                      0,8668

                      576,7470

                      0,1862

                      0,1267

                      397,7409

                      0,1628

                      1,5823

                      327,1568

                      0,1473

                      27

                      0,3091

                      754,8518

                      0,1805

                      0,8668

                      594,3196

                      0,1861

                      0,1267

                      405,3735

                      0,1614

                      1,5823

                      331,4000

                      0,1488

                      28

                      0,3091

                      763,4054

                      0,1758

                      0,8668

                      611,9863

                      0,1860

                      0,1267

                      413,3799

                      0,1601

                      1,5823

                      335,4719

                      0,1502

                      29

                      0,3091

                      772,1960

                      0,1711

                      0,8668

                      629,6783

                      0,1858

                      0,1267

                      421,4867

                      0,1587

                      1,5823

                      339,4979

                      0,1516

                      30

                      0,3091

                      780,9891

                      0,1663

                      0,8668

                      647,3706

                      0,1857

                      0,1267

                      429,5945

                      0,1573

                      1,5823

                      343,5234

                      0,1531

                      LMS, L = skewness of the distribution, M = median, and S = variance.

                      Aortic distensibility and PWV

                      The mean values of aortic distensibility and PWV are presented in Table 4. Figures 4 and 5 show the gender specific percentiles for aortic distensibility and PWV. In Tables 8, 9, 10 the original L, M and S values for aortic distensibility and PWV are given. An age-related decrease of aortic distensibility was found for all anatomical locations (r = -0.43 to -0.52, p < 0.001). Aortic distensibility also correlated with height (r = -0.47 to -0.62, p < 0.001) and body weight (r = -0.45 to -0.59, p < 0.001), BSA (r = -0.47 to -0.61, p < 0.001). Univariate regression analysis showed a modest association between PWV and the following parameters: age, height, weight and BSA (r = 0.25 to 0.32, p = 0.047 to 0.009).
                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Fig4_HTML.jpg
                      Figure 4

                      Gender-specific reference percentiles for aortic distensibility at four locations: a) ascending aorta, b) aortic arch, c) aortic isthmus and d) descending aorta above the diaphragm.

                      http://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_2642_Fig5_HTML.jpg
                      Figure 5

                      Gender-specific reference percentiles for PWV in the aortic arch.

                      Table 8

                      LMS parameters for aortic distensibility relative to age for girls

                       

                      Ascending aorta

                      Aortic arch

                      Aortic isthmus

                      Descending aorta above the diaphragm

                      Age

                      L

                      M

                      S

                      L

                      M

                      S

                      L

                      M

                      S

                        L

                        M

                        S

                      0

                      -0,0721

                      12,7303

                      0,2388

                      0,2825

                      10,1659

                      0,2971

                      -0,2728

                      12,7827

                      0,2097

                      0,3847

                      11,6928

                      0,2263

                      1

                      -0,0721

                      12,5028

                      0,2396

                      0,2825

                      10,0908

                      0,3006

                      -0,2728

                      12,3919

                      0,2100

                      0,3847

                      11,5113

                      0,2297

                      2

                      -0,0721

                      12,2753

                      0,2403

                      0,2825

                      10,0157

                      0,3041

                      -0,2728

                      12,0010

                      0,2102

                      0,3847

                      11,3298

                      0,2331

                      3

                      -0,0721

                      12,0477

                      0,2411

                      0,2825

                      9,9404

                      0,3076

                      -0,2728

                      11,6098

                      0,2104

                      0,3847

                      11,1483

                      0,2366

                      4

                      -0,0721

                      11,8176

                      0,2419

                      0,2825

                      9,8619

                      0,3110

                      -0,2728

                      11,2134

                      0,2106

                      0,3847

                      10,9668

                      0,2400

                      5

                      -0,0721

                      11,5817

                      0,2427

                      0,2825

                      9,7752

                      0,3145

                      -0,2728

                      10,8041

                      0,2108

                      0,3847

                      10,7853

                      0,2434

                      6

                      -0,0721

                      11,3421

                      0,2435

                      0,2825

                      9,6765

                      0,3180

                      -0,2728

                      10,3772

                      0,2110

                      0,3847

                      10,6038

                      0,2469

                      7

                      -0,0721

                      11,1121

                      0,2443

                      0,2825

                      9,5629

                      0,3215

                      -0,2728

                      9,9344

                      0,2112

                      0,3847

                      10,4223

                      0,2503

                      8

                      -0,0721

                      10,9051

                      0,2451

                      0,2825

                      9,4311

                      0,3250

                      -0,2728

                      9,4780

                      0,2114

                      0,3847

                      10,2408

                      0,2537

                      9

                      -0,0721

                      10,7290

                      0,2459

                      0,2825

                      9,2748

                      0,3285

                      -0,2728

                      9,0114

                      0,2117

                      0,3847

                      10,0593

                      0,2572

                      10

                      -0,0721

                      10,5679

                      0,2467

                      0,2825

                      9,0871

                      0,3320

                      -0,2728

                      8,5463

                      0,2119

                      0,3847

                      9,8778

                      0,2606

                      11

                      -0,0721

                      10,3851

                      0,2474

                      0,2825

                      8,8635

                      0,3354

                      -0,2728

                      8,1077

                      0,2121

                      0,3847

                      9,6963

                      0,2640

                      12

                      -0,0721

                      10,1582

                      0,2482

                      0,2825

                      8,6056

                      0,3389

                      -0,2728

                      7,7159

                      0,2123

                      0,3847

                      9,5149

                      0,2675

                      13

                      -0,0721

                      9,8884

                      0,2490

                      0,2825

                      8,3257

                      0,3424

                      -0,2728

                      7,3784

                      0,2125

                      0,3847

                      9,3334

                      0,2709

                      14

                      -0,0721

                      9,5911

                      0,2498

                      0,2825

                      8,0371

                      0,3459

                      -0,2728

                      7,0939

                      0,2127

                      0,3847

                      9,1519

                      0,2743

                      15

                      -0,0721

                      9,2905

                      0,2506

                      0,2825

                      7,7528

                      0,3494

                      -0,2728

                      6,8625

                      0,2129

                      0,3847

                      8,9705

                      0,2777

                      16

                      -0,0721

                      9,0033

                      0,2514

                      0,2825

                      7,4850

                      0,3529

                      -0,2728

                      6,6852

                      0,2131

                      0,3847

                      8,7890

                      0,2812

                      17

                      -0,0721

                      8,7345

                      0,2522

                      0,2825

                      7,2434

                      0,3563

                      -0,2728

                      6,5631

                      0,2134

                      0,3847

                      8,6076

                      0,2846

                      18

                      -0,0721

                      8,4850

                      0,2529

                      0,2825

                      7,0315

                      0,3598

                      -0,2728

                      6,4885

                      0,2136

                      0,3847

                      8,4262

                      0,2880

                      19

                      -0,0721

                      8,2574

                      0,2537

                      0,2825

                      6,8508

                      0,3633

                      -0,2728

                      6,4533

                      0,2138

                      0,3847

                      8,2448

                      0,2915

                      20

                      -0,0721

                      8,0546

                      0,2545

                      0,2825

                      6,6995

                      0,3668

                      -0,2728

                      6,4449

                      0,2140

                      0,3847

                      8,0635

                      0,2949

                      21

                      -0,0721

                      7,8749

                      0,2553

                      0,2825

                      6,5740

                      0,3703

                      -0,2728

                      6,4447

                      0,2142

                      0,3847

                      7,8822

                      0,2983

                      22

                      -0,0721

                      7,7106

                      0,2561

                      0,2825

                      6,4710

                      0,3738

                      -0,2728

                      6,4391

                      0,2144

                      0,3847

                      7,7008

                      0,3017

                      23

                      -0,0721

                      7,5479

                      0,2569

                      0,2825

                      6,3882

                      0,3772

                      -0,2728

                      6,4264

                      0,2146

                      0,3847

                      7,5195

                      0,3052

                      24

                      -0,0721

                      7,3842

                      0,2577

                      0,2825

                      6,3235

                      0,3807

                      -0,2728

                      6,4171

                      0,2148

                      0,3847

                      7,3382

                      0,3086

                      25

                      -0,0721

                      7,2113

                      0,2584

                      0,2825

                      6,2744

                      0,3842

                      -0,2728

                      6,4170

                      0,2150

                      0,3847

                      7,1570

                      0,3120

                      26

                      -0,0721

                      7,0343

                      0,2592

                      0,2825

                      6,2371

                      0,3877

                      -0,2728

                      6,4317

                      0,2152

                      0,3847

                      6,9757

                      0,3155

                      27

                      -0,0721

                      6,8647

                      0,2600

                      0,2825

                      6,2084

                      0,3912

                      -0,2728

                      6,4666

                      0,2154

                      0,3847

                      6,7944

                      0,3189

                      28

                      -0,0721

                      6,6951

                      0,2608

                      0,2825

                      6,1806

                      0,3947

                      -0,2728

                      6,5104

                      0,2156

                      0,3847

                      6,6132

                      0,3223

                      29

                      -0,0721

                      6,5250

                      0,2616

                      0,2825

                      6,1527

                      0,3981

                      -0,2728

                      6,5550

                      0,2158

                      0,3847

                      6,4319

                      0,3257

                      30

                      -0,0721

                      6,3550

                      0,2624

                      0,2825

                      6,1249

                      0,4016

                      -0,2728

                      6,5997

                      0,2160

                      0,3847

                      6,2506

                      0,3292

                      LMS, L = skewness of the distribution, M = median, and S = variance.

                      Table 9

                      LMS parameters for aortic distensibility relative to age for boys

                       

                      Ascending aorta

                      Aortic arch

                      Aortic isthmus

                      Descending aorta above the diaphragm

                      Age

                      L

                      M

                      S

                      L

                      M

                      S

                      L

                      M

                      S

                        L

                        M

                        S

                      0

                      -0,1879

                      12,3602

                      0,3680

                      0,0801

                      10,2881

                      0,3061

                      -0,2022

                      9,4472

                      0,3533

                      -0,0079

                      9,4241

                      0,3478

                      1

                      -0,1879

                      11,9220

                      0,3680

                      0,0801

                      10,1050

                      0,3061

                      -0,2022

                      9,2308

                      0,3494

                      -0,0079

                      9,2938

                      0,3441

                      2

                      -0,1879

                      11,4838

                      0,3680

                      0,0801

                      9,9218

                      0,3061

                      -0,2022

                      9,0144

                      0,3454

                      -0,0079

                      9,1635

                      0,3404

                      3

                      -0,1879

                      11,0456

                      0,3680

                      0,0801

                      9,7386

                      0,3061

                      -0,2022

                      8,7980

                      0,3415

                      -0,0079

                      9,0331

                      0,3367

                      4

                      -0,1879

                      10,6075

                      0,3680

                      0,0801

                      9,5554

                      0,3061

                      -0,2022

                      8,5816

                      0,3375

                      -0,0079

                      8,9028

                      0,3330

                      5

                      -0,1879

                      10,1700

                      0,3680

                      0,0801

                      9,3705

                      0,3061

                      -0,2022

                      8,3685

                      0,3335

                      -0,0079

                      8,7730

                      0,3293

                      6

                      -0,1879

                      9,7343

                      0,3680

                      0,0801

                      9,1780

                      0,3061

                      -0,2022

                      8,1629

                      0,3296

                      -0,0079

                      8,6433

                      0,3256

                      7

                      -0,1879

                      9,2990

                      0,3680

                      0,0801

                      8,9719

                      0,3061

                      -0,2022

                      7,9576

                      0,3256

                      -0,0079

                      8,5103

                      0,3219

                      8

                      -0,1879

                      8,8602

                      0,3680

                      0,0801

                      8,7467

                      0,3061

                      -0,2022

                      7,7410

                      0,3216

                      -0,0079

                      8,3694

                      0,3182

                      9

                      -0,1879

                      8,4151

                      0,3680

                      0,0801

                      8,4980

                      0,3061

                      -0,2022

                      7,4918

                      0,3177

                      -0,0079

                      8,2157

                      0,3145

                      10

                      -0,1879

                      7,9776

                      0,3680

                      0,0801

                      8,2310

                      0,3061

                      -0,2022

                      7,2033

                      0,3137

                      -0,0079

                      8,0497

                      0,3108

                      11

                      -0,1879

                      7,5683

                      0,3680

                      0,0801

                      7,9577

                      0,3061

                      -0,2022

                      6,8970

                      0,3098

                      -0,0079

                      7,8764

                      0,3071

                      12

                      -0,1879

                      7,2051

                      0,3680

                      0,0801

                      7,6865

                      0,3061

                      -0,2022

                      6,6042

                      0,3058

                      -0,0079

                      7,7035

                      0,3034

                      13

                      -0,1879

                      6,9030

                      0,3680

                      0,0801

                      7,4220

                      0,3061

                      -0,2022

                      6,3480

                      0,3018

                      -0,0079

                      7,5379

                      0,2997

                      14

                      -0,1879

                      6,6697

                      0,3680

                      0,0801

                      7,1669

                      0,3061

                      -0,2022

                      6,1310

                      0,2979

                      -0,0079

                      7,3831

                      0,2959

                      15

                      -0,1879

                      6,5089

                      0,3680

                      0,0801

                      6,9220

                      0,3061

                      -0,2022

                      5,9529

                      0,2939

                      -0,0079

                      7,2400

                      0,2922

                      16

                      -0,1879

                      6,4138

                      0,3680

                      0,0801

                      6,6851

                      0,3061

                      -0,2022

                      5,8175

                      0,2899

                      -0,0079

                      7,1082

                      0,2885

                      17

                      -0,1879

                      6,3729

                      0,3680

                      0,0801

                      6,4532

                      0,3061

                      -0,2022

                      5,7175

                      0,2860

                      -0,0079

                      6,9844

                      0,2848

                      18

                      -0,1879

                      6,3745

                      0,3680

                      0,0801

                      6,2234

                      0,3061

                      -0,2022

                      5,6445

                      0,2820

                      -0,0079

                      6,8653

                      0,2811

                      19

                      -0,1879

                      6,4062

                      0,3680

                      0,0801

                      5,9926

                      0,3061

                      -0,2022

                      5,5886

                      0,2781

                      -0,0079

                      6,7467

                      0,2774

                      20

                      -0,1879

                      6,4551

                      0,3680

                      0,0801

                      5,7579

                      0,3061

                      -0,2022

                      5,5400

                      0,2741

                      -0,0079

                      6,6246

                      0,2737

                      21

                      -0,1879

                      6,5111

                      0,3680

                      0,0801

                      5,5167

                      0,3061

                      -0,2022

                      5,4988

                      0,2701

                      -0,0079

                      6,4987

                      0,2700

                      22

                      -0,1879

                      6,5646

                      0,3680

                      0,0801

                      5,2667

                      0,3061

                      -0,2022

                      5,4678

                      0,2662

                      -0,0079

                      6,3697

                      0,2663

                      23

                      -0,1879

                      6,6062

                      0,3680

                      0,0801

                      5,0054

                      0,3061

                      -0,2022

                      5,4496

                      0,2622

                      -0,0079

                      6,2384

                      0,2626

                      24

                      -0,1879

                      6,6277

                      0,3680

                      0,0801

                      4,7261

                      0,3061

                      -0,2022

                      5,4328

                      0,2583

                      -0,0079

                      6,1017

                      0,2589

                      25

                      -0,1879

                      6,6242

                      0,3680

                      0,0801

                      4,4155

                      0,3061

                      -0,2022

                      5,3874

                      0,2543

                      -0,0079

                      5,9498

                      0,2552

                      26

                      -0,1879

                      6,5975

                      0,3680

                      0,0801

                      4,0684

                      0,3061

                      -0,2022

                      5,3095

                      0,2503

                      -0,0079

                      5,7759

                      0,2515

                      27

                      -0,1879

                      6,5577

                      0,3680

                      0,0801

                      3,6929

                      0,3061

                      -0,2022

                      5,2154

                      0,2464

                      -0,0079

                      5,5826

                      0,2478

                      28

                      -0,1879

                      6,5116

                      0,3680

                      0,0801

                      3,3021

                      0,3061

                      -0,2022

                      5,1114

                      0,2424

                      -0,0079

                      5,3785

                      0,2441

                      29

                      -0,1879

                      6,4643

                      0,3680

                      0,0801

                      2,9079

                      0,3061

                      -0,2022

                      5,0026

                      0,2384

                      -0,0079

                      5,1722

                      0,2404

                      30

                      -0,1879

                      6,4170

                      0,3680

                      0,0801

                      2,5137

                      0,3061

                      -0,2022

                      4,8936

                      0,2345

                      -0,0079

                      4,9658

                      0,2367

                      LMS, L = skewness of the distribution, M = median, and S = variance.

                      Table 10

                      LMS parameters for PWV relative to age and gender

                       

                      Male

                      Female

                      Age

                      L

                      M

                      S

                      L

                      M

                      S

                      0

                      1,4844

                      3,4147

                      0,2122

                      -1,5196

                      2,7808

                      0,1468

                      1

                      1,4844

                      3,4367

                      0,2122

                      -1,5196

                      2,8144

                      0,1469

                      2

                      1,4844

                      3,4587

                      0,2122

                      -1,5196

                      2,8481

                      0,1469

                      3

                      1,4844

                      3,4808

                      0,2122

                      -1,5196

                      2,8817

                      0,1469

                      4

                      1,4844

                      3,5028

                      0,2122

                      -1,5196

                      2,9154

                      0,1470

                      5

                      1,4844

                      3,5248

                      0,2122

                      -1,5196

                      2,9490

                      0,1470

                      6

                      1,4844

                      3,5469

                      0,2122

                      -1,5196

                      2,9827

                      0,1470

                      7

                      1,4844

                      3,5689

                      0,2122

                      -1,5196

                      3,0163

                      0,1470

                      8

                      1,4844

                      3,5909

                      0,2122

                      -1,5196

                      3,0499

                      0,1471

                      9

                      1,4844

                      3,6129

                      0,2122

                      -1,5196

                      3,0836

                      0,1471

                      10

                      1,4844

                      3,6350

                      0,2122

                      -1,5196

                      3,1172

                      0,1471

                      11

                      1,4844

                      3,6570

                      0,2122

                      -1,5196

                      3,1509

                      0,1471

                      12

                      1,4844

                      3,6790

                      0,2122

                      -1,5196

                      3,1845

                      0,1472

                      13

                      1,4844

                      3,7011

                      0,2122

                      -1,5196

                      3,2182

                      0,1472

                      14

                      1,4844

                      3,7231

                      0,2122

                      -1,5196

                      3,2518

                      0,1472

                      15

                      1,4844

                      3,7451

                      0,2122

                      -1,5196

                      3,2855

                      0,1473

                      16

                      1,4844

                      3,7672

                      0,2122

                      -1,5196

                      3,3192

                      0,1473

                      17

                      1,4844

                      3,7892

                      0,2122

                      -1,5196

                      3,3528

                      0,1473

                      18

                      1,4844

                      3,8112

                      0,2122

                      -1,5196

                      3,3865

                      0,1473

                      19

                      1,4844

                      3,8333

                      0,2122

                      -1,5196

                      3,4201

                      0,1474

                      20

                      1,4844

                      3,8553

                      0,2122

                      -1,5196

                      3,4538

                      0,1474

                      21

                      1,4844

                      3,8773

                      0,2122

                      -1,5196

                      3,4875

                      0,1474

                      22

                      1,4844

                      3,8994

                      0,2122

                      -1,5196

                      3,5211

                      0,1475

                      23

                      1,4844

                      3,9214

                      0,2122

                      -1,5196

                      3,5548

                      0,1475

                      24

                      1,4844

                      3,9434

                      0,2122

                      -1,5196

                      3,5885

                      0,1475

                      25

                      1,4844

                      3,9655

                      0,2122

                      -1,5196

                      3,6221

                      0,1476

                      26

                      1,4844

                      3,9875

                      0,2122

                      -1,5196

                      3,6558

                      0,1476

                      27

                      1,4844

                      4,0096

                      0,2122

                      -1,5196

                      3,6895

                      0,1476

                      28

                      1,4844

                      4,0316

                      0,2122

                      -1,5196

                      3,7231

                      0,1476

                      29

                      1,4844

                      4,0536

                      0,2122

                      -1,5196

                      3,7568

                      0,1477

                      30

                      1,4844

                      4,0757

                      0,2122

                      -1,5196

                      3,7905

                      0,1477

                      LMS, L = skewness of the distribution, M = median, and S = variance.

                      Discussion

                      This CMR study describes the quantile distribution of cross-sectional areas, distensibility and PWV of the thoracic aorta in heart-healthy children and young adults between their 3rd and 29th year of life. Defining the normal range for aortic size and bio-elastic properties is an important aid in the early detection of adverse aortic changes.

                      Aortic dimensions

                      Knowledge of the size of the thoracic aorta is important for the treatment of patients with congenital and acquired cardiovascular diseases. CMR allows an exact assessment of the aortic anatomy, independent of acoustic windows, and is therefore an optimal tool to detect anatomic abnormalities of the aorta such as dilatation or aneurysm formation [17]. We provide normal data for aortic cross-sectional areas in the form of percentile curves by age and gender. Normal data for aortic dimensions in children have been reported in various echocardiographic [18], angiocardiographic [19, 20] and CMR studies [21, 22].

                      The CMR study from Kaiser et al. [20] reported aortic diameters measured by contrast-enhanced (CE) CMR angiography in 53 children. This method was limited by the fact that CE-CMR images are static and represent a summation of all cardiac phases which may affect a comparison to ECG-gated acquisitions such as in echocardiography or in our study. Furthermore, they measured aortic diameters instead of cross-sectional areas.

                      Another early CMR-study from Mohiaddin et al. [22] assessed aortic cross-sectional areas from enddiastolic spin echo images in 70 predominantly adult volunteers between the ages of 10 and 83 years. We confirmed their finding that aortic dimensions are positively correlated with age, but our study also covers children younger than 10 years, an age range where aortic dimensions and cardiac structures change rapidly according to somatic growth in prepubertal children [23]. Normal data for aortic cross-sectional areas have been reported by Rammos et al using angiocardiography [19]. As in our study, they showed a good correlation between BSA and aortic cross-sectional areas. However, their reported data are smaller than in our study, which may be mainly caused by the different technique.

                      However, the data from the mentioned studies are not exactly comparable to our measurements. Most studies used different imaging modalities [1820]. Furthermore, they report aortic diameters, or measured them in order to calculate cross-sectional areas [18]. CMR allows a direct measurement of aortic cross-sectional areas which is a more accurate approach to assess aortic size, since vessels are not circular in all segments and show an inter-individual anatomic variability.

                      The observed quantile distributions for aortic dimensions are of clinical value to detect pathologic anatomical changes of the aorta in children and young adults and will serve as reference values for future CMR research studies.

                      Aortic distensibility and PWV

                      This is the first study to provide reference CMR values for aortic distensibility and PWV in children and young adults, in conjunction with measurements of aortic size. The percentile ranges show that aortic distensibility decreases with age, whereas PWV increases with age. Age-associated changes and reference values of aortic distensibility and PWV in children and adults have also been reported in studies using different techniques. Senzaki et al. examined 112 patients with an age range from 6 months to 20 years by cardiac catherization. They showed that the arterial compliance normalized to body surface area significantly decreased with age [24]. The study by Avioli et al. used transcutaneous Doppler techniques to assess aortic PWV in subjects with an age range from 3 to 89 years. In their study aortic PWV significantly increased with age [25]. Another study measured PWV with ultrasound methods in 206 patients aged 0–15 years. Their median PWV was 3.04 m/s which is comparable to our data. However, in contrast to our study PWV was independent of age, which may be caused by the young age of their study group [26]. CMR assessment of aortic PWV showed good agreement with PWV obtained from invasive pressure measurements as the gold standard [27]. Unlike in ultrasound CMR is not limited to acoustic windows and does not only provide an estimation of aortic PWV [1, 27].

                      The aorta acts as a conduit delivering blood to the peripheral organs and transforms the pulsatile effect caused by ventricular ejection into a continuous blood flow [1]. As shown aortic distensibility decreases and PWV increases during age. The decreasing aortic elasticity observed in our young cohort may be related to normal structural wall changes during aging [28]. An increase in intimal-medial thickness after birth has been demonstrated in an earlier study [28]. The aortic elastic properties depend largely on the presence of elastic fibres in the vessel wall, which have a maximum rate in the perinatal period followed by a fast decrease already during childhood [29]. Besides these developmental changes aortic wall mechanics and stress seems to play an important role in aortic stiffening. In the course of a lifetime the human aorta will undergo billions of cycles of expansion and contractions. This cyclic mechanical stress leads to fragmentation of elastic fibres and causes a transfer of stress to the stiffer collagen fibres. The loss of elastin results in a reduction of aortic elasticity [30]. In adults, decreased aortic elasticity has adverse effects on cardiac systolic and diastolic function, due to increased left ventricular afterload and myocardial oxygen consumption as well as impaired coronary perfusion [31].

                      Our data may be of interest in various diseases and pathological conditions that can affect aortic bioelasticity already in children and young adults. Impaired aortic bioelasticity has been reported for instance in patients with Marfan syndrome [14], tetralogy of Fallot [5], Turner’s syndrome [32] and aortic coarctation [4]. In a recently published study we could show that patients with hypoplastic left heart syndrome have severly reduced aortic distensibility [3]. Furthermore, some functional vascular parameters are impaired in obese children [33]. Considering the increasing use of CMR for non-invasive scientific and clinical studies, the presented data may help in evaluating aortic bioelastic function and cardiovascular risk stratification with these diseases.

                      Limitations

                      As it is difficult to recruit healthy children as volunteers for a CMR study, the sample size of our cohort is small in comparison to echocardiographic studies but fulfills the demand for statistical evaluation.

                      Conclusions

                      We provide percentiles for aortic cross-sectional areas, aortic distensibilty and PWV for children at various ages. They can be of clinical value in patients with various cardiac and vascular diseases and may serve as reference values for further CMR research studies.

                      Declarations

                      Acknowledgements

                      We thank the Fördergemeinschaft Deutsche Kinderherzzentren e.V. (Friedrich-Wilhelm-Straße 45, 53113 Bonn, http://​www.​kinderherzen.​de) for their financial support.

                      Authors’ Affiliations

                      (1)
                      Department of Congenital Heart Disease and Pediatric Cardiology, University Hospital of Schleswig-Holstein
                      (2)
                      Department for Medical Informatics and Statistics, University Hospital of Schleswig-Holstein
                      (3)
                      Department of Radiology, Brigham & Women’s Hospital, Harvard University

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                      © Voges et al.; licensee BioMed Central Ltd. 2012

                      This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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