Abstract 3649: Aortic Characterization in Patients with Congenital Bicuspid Aortic Valves Using MR Flow Mapping
Background: Patients with congenital bicuspid aortic valves (BAV) manifest with a higher rate of aortic root dilatation and a nine fold greater risk of aortic dissection. However, clear criteria to identify susceptible individuals are lacking. In Marfan’s syndrome, aortic dilation and dissection have been shown to correlate with abnormal aortic distensibility and stiffness, which are independent predictors of aortic dilatation.
Objective: The aim of this study was to determine whether patients with BAV exhibit early changes in biophysical properties associated with increased aortic dilation.
Methods: Congenital BAV patients were subdivided into two groups (< 1.82 cm/m2, n=5; > 1.82 cm//m2, n=15) based upon the mean aortic diameter index (aortic diameter/BSA) and compared to a third control group (< 1.82 cm/m2, n=18) with trileaflet aortic valves. Aortic diameter, translumenal area and MR flow mapping were performed at three locations within the aorta (1, ascending aortic arch; 2, descending aortic arch; 3, abdominal aorta). Blood pressure was measured prior to each MR scan. Distensibility at each location and flow wave velocity (FWV) between location 1 to 2, location 2 to 3, and location 1 to 3 were calculated.
Results: Patients with normal aortic valves had smaller aortic roots (2.97 ± 0.27 cm versus 3.51 ± 0.55 cm, p = 0.0002) and aortic indexes (1.52 ± 0.17 versus 1.82 ± 0.33, p = 0.0006) than did BAV patients. Distensibility at the level of the ascending aortic arch was significantly lower in BAV patients compared to normal patients (6.24 ± 2.45 x10−3 mmHg−1 versus 9.76 ± 4.16 x10-3 mmHg-1, p = 0.005). This difference was not appreciated in BAV patients with smaller aortic dimensions (aortic index < 1.81 cm/m2). Normal aortic valve patients had lower FWV’s in the ascending arch relative to their descending aortic arch (segment 1 versus segment 2). This phenomenon was not seen in BAV patients.
Conclusions: Non-invasive MR measurement of distensibility and FWV reveals abnormal compliance of the ascending aortic arch in BAV patients. These results parallel similar abnormalities in Marfan’s patients. MR-based characterization may help identify and characterize patients with congenital bicuspid aortic valves at greater risk for aortic dilatation or dissection.