The Marfan syndrome: abnormal aortic elastic properties

Aortic distensibility and aortic stiffness index were measured at the ascending aorta (3 cm above the aortic valve) and the mid-portion of the abdominal aorta from the changes in echocardiographic diameters and pulse pressure in 14 patients with the Marfan syndrome and 15 age- and gender-matched normal control subjects. The following formulas were used: 1) Aortic distensibility = 2(Changes in aortic diameter)/(Diastolic aortic diameter) (Pulse pressure); and 2) Aortic stiffness index = ln(Systolic blood pressure)/(Diastolic blood pressure)(Changes in aortic diameter)/Diastolic aortic diameter. Pulse wave velocity was also measured. Compared with normal subjects, patients with the Marfan syndrome had decreased aortic distensibility in the ascending and the abdominal aorta (2.9 +/- 1.3 vs. 5.6 +/- 1.4 cm2 dynes-1, p less than 0.001 and 4.5 +/- 2.1, vs. 7.7 +/- 2.5, cm2 dynes-1, p less than 0.001, respectively) and had an increased aortic stiffness index in the ascending and the abdominal aorta (10.9 +/- 5.6 vs. 5.9 +/- 2.2, p less than 0.005 and 7.1 +/- 3.1 vs. 3.9 +/- 1.2, p less than 0.005, respectively). Aortic diameters in the ascending aorta were larger in these patients than in normal subjects, but those in the abdominal aorta were similar in the two groups. Linear correlations for both aortic distensibility and stiffness index were found between the ascending and the abdominal aorta (r = 0.85 and 0.71, respectively). Pulse wave velocity was more rapid in the patients than in the normal subjects (11.6 +/- 2.5 vs. 9.5 +/- 1.4 m/s, respectively, p less than 0.01). Thus, aortic elastic properties are abnormal in patients with the Marfan syndrome irrespective of the aortic diameter, which suggests an intrinsic abnormality of the aortic arterial wall.