Open Access

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

  • Inga Voges1,
  • Michael Jerosch-Herold3,
  • Jürgen Hedderich2,
  • Eileen Pardun1,
  • Christopher Hart1,
  • Dominik Daniel Gabbert1,
  • Jan Hinnerk Hansen1,
  • Colin Petko1,
  • Hans-Heiner Kramer1 and
  • Carsten Rickers1Email author
Contributed equally
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 (Figure1). 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.
https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_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 (Figure2): 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.
https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_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:
Distensibility 1 0 3 mm Hg 1 = A max A min / A min x P max P min , where https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_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:
PWV = Δ x / Δ t , https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_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, Figure1). Furthermore mean aortic blood flow and peak systolic velocity were assessed in the ascending aorta (Table2).
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:
C α = M * 1 + L * S * z α 1 / L , https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_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):
z score = X / M L 1 / L * S . https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_2642_Equd_HTML.gif

Results

The study group characteristics are presented in Table3. 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

Table4 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) (Table5). Gender specific percentile curves between aortic cross-sectional areas and age are shown in Figure3. Additionally, Tables6 and7 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.

https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_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 Table4. Figures4 and5 show the gender specific percentiles for aortic distensibility and PWV. In Tables8,9,10 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).
https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_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.

https://static-content.springer.com/image/art%3A10.1186%2F1532-429X-14-77/MediaObjects/12968_2011_Article_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.

Notes

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, Campus Kiel
(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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