CHANGES IN AORTIC DISTENSIBILITY AND PULSE-WAVE VELOCITY ASSESSED WITH MAGNETIC-RESONANCE-IMAGING FOLLOWING BETA-BLOCKER THERAPY IN THE MARFAN-SYNDROME

It has been shown that p-adrenergic blocking agents may reduce the rat e of aortic root dilation and the development of aortic complications in patients with the Marfan syndrome. This may be due to beta-blocker- induced changes in aortic stiffness, of which distensibility and pulse wave velocity are in vivo measurable derivatives. We studied changes in distensibility at 4 levels of the aorta and pulse wave velocity alo ng the entire aorta after 2 weeks of beta-blocker therapy in 6 Marfan syndrome patients and in 6 healthy volunteers, using magnetic resonanc e imaging (MRI) combined with brachial artery blood pressure measureme nts. In bath groups, mean blood pressure decreased significantly (Marf an: 86 +/- 6 vs 78 +/- 5 mm Hg, p <0.05; control: 80 +/- 8 vs 73 +/- 3 mm Hg, p <0.05) (all data expressed as mean +/-1SD).At baseline, the Marfan syndrome patients exhibited decreased distensibility at the lev el of the ascending aorta (2 +/- 1 vs 6 +/- 2 10(-3)mm Hg-1, p <0.01) and increased pulse wave velocity (6.2 +/- 0.4 vs 3.9 +/- 0.4 (-1), p <0.01) compared with control subjects. Only ms the Marfan syndrome pat ients had a significant increase in aortic distensibility at multiple levels and a significant decrease in pulse wave velocity after P-block er therapy (ascending aorta distensibility: 2 -1 1 vs 4 +/- 1 10(-3)mm Hg-1, p <0.05; abdominal aorta distensibility: 5 +/- 2 vs 8 +/- 3 10- 3mm Hg-1, p <0.05; pulse wave velocity: 6.2 +/- 0.4 vs 5.0 +/- 1.0 ms( -1), p <0.05). Thus,aortic stiffness in Marfan syndrome, together with mean blood pressure, is reduced by P-blocker therapy, and MRI is well suited to detect these changes by measuring distensibility and pulse wave velocity. (C) 1998 by Excerpta Medico, Inc.