Relation between age and aortic wall compliance in the Marfan syndrome: evaluation with Velocity-Encoded MRI

Introduction

Progressive aortic root dilatation due to reduced compliance often leads to dissection in Marfan syndrome. Aging also has progressive negative effect on compliance.

Purpose

To describe age-related change in compliance, expressed in Pulse Wave Velocity (PWV), Distensibility (Dist) and Stiffness Index (SI), with Phase-Contrast (PC) MRI in Marfan syndrome.

Methods

Twenty-five patients (mean age 36 ± 14 years, range 18-63 years, 13 men) with Marfan syndrome and twenty-five age/gender-matched healthy volunteers were examined. None of the patients had undergone elective aorta replacement. Informed consent and medical ethical approval was obtained.

MRI was performed on 1.5 T Philips Achieva MRI (Philips Medical Systems, Best, The Netherlands). PC-MRI with through-plane velocity encoding (V_enc = 150 cm/s) and free-breathing was performed perpendicular to the ascending and descending aorta at the level transecting the pulmonary trunk. Another acquisition (V_enc = 100 cm/s) was performed at the abdominal aorta. PWV was determined for the aortic arch (AA), distal aorta (DA) and total aorta using the transit-time method described by Grotenhuis.¹ Brachial-cuff systolic and diastolic blood pressure (BP) were obtained. Distensibility (= luminal area change/(diastolic luminal area × pulse pressure)) and Stiffness Index (= ln [(BP_Systolic/BP_Diastolic)/(diameter change/diastolic diameter)]) were determined at the ascending aorta in gradient-echo PC-MRI magnitude images. Reduced wall compliance is expressed as increased PWV and SI and decreased Dist. PWV, Dist and SI were compared in Marfan and controls using paired t-tests. Age relation was determined by linear regression.

Results

See tables 1 and 2 and figure 1.

Figure 1

Table 1 Compliance in Marfan versus healthy controls.

Table 2 Age-related compliance by linear regression A × age + B.

In Marfan, PWV is increased at AA, DA and total aorta. Dist is decreased. SI not statistically significantly different. In Figure 1, age relation of PWV_tot is shown.

PWV in AA, DA and total aorta shows significant increase with age: 7 cm/s to 10 cm/s increase in PWV per year; except PWV_AA in controls only shows 3 cm/s increase per year. Age relation of Dist and SI was not statistically proven, except only for increasing SI in controls.

Conclusion

Age-related increase in aortic wall compliance can be studied with Phase-Contrast MRI. Patients with Marfan syndrome present with increased Pulse Wave Velocity and stiffness index and decreased distensibility. Age-related change in compliance is expressed in increasing PWV.