Prosthetic Valves for the Small Aortic Root

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Abstract
Mechanical aortic valves (AVs) are frequently implanted in small (19 and 21 mm) aortic roots because bioprosthetic valves have unacceptably high gradients and many surgeons do not implant allograft valves. Three mechanical valves in common use today in the United States are the Starr-Edwards (SE), St. Jude Medical (SJ), and the Medtronic-Hall (MH). Clinical hemodynamic studies reveal that the 21-mm SE valve (size 8A) has peak systolic gradients of 13 to 58 mmHg (N = 6) with a calculated effective orifice of 0.7 to 1.4 cm2. The 19-mm SJ valve has a gradient at peak pressure of 17 mmHg and a mean gradient of 22 mmHg (N = 6) with respective exercise gradients of 32 and 38 mmHg (N = 5). For the 21-mm SJ valve the mean gradient was 5.2 +/- 5.3 (N +/- 12) and the gradient at peak pressure was 6.0 mmHg (N = 15). The 21-mm MH valve had resting gradients at peak pressure of 10.5 (N = 3) and 12.4 mmHg (N = 9) and exercise gradients of 15.8 mmHg (N = 9). Six months after AV replacement with small SJ or MH (N = 14) or large (23 mm or greater) (N = 83) valves, cardiac output was 4.7 versus 6.4 L/min (p < 0.03), percent reduction in left ventricular mass index (LVMI) was -8% versus -21% (p < 0.01), exercise duration was 370 versus 555 seconds, and congestive heart failure (CHF) class was 1.9 versus 1.1 (p < 0.0001). Change in LVMI and valve size were the only independent predictors of CHF class.(ABSTRACT TRUNCATED AT 250 WORDS)