Comparison of transprosthetic mean pressure gradients between Medtronic Hall and ATS valves in the aortic position

Aim of the study: Several studies have shown the inferior performance of small prostheses in the narrow aortic root. However, modern low-profile mechanical prostheses have improved hemodynamic performance characteristics. By measuring the transprosthetic pressure gradient in vivo, we were able to characterize the hemodynamic features of two prostheses: the ATS Medical (ATS) and the Medtronic Hall (MH) valves. Methods: From October 1994 to April 2002, 113 patients received an aortic valve replacement (AVR) with either an ATS or a MH valve. The transprosthetic pressure gradients, calculated from a simplified Bernoulli equation during immediate postoperative Doppler echocardiographic examination, were compared for differently sized prostheses with respect to body surface area (BSA). Results: The mean pressure gradients and the mean BSAs were: 27.8±14.8 mm Hg and 1.50±0.10 m² in ATS 19 mm (n=7), 20.4±8.5 mm Hg and 1.54±0.11 m² in ATS 21 mm (n=22), 13.0±5.7 mm Hg, 1.70±0.13 m² in ATS 23 mm (n=22), 10.9±3.5 mm Hg and 1.81±0.16 m² in ATS 25 mm (n=19), 9.3±0.6 mm Hg and 1.72±0.17 m² in ATS 27 mm (n=4), 13.5±6.5 mm Hg and 1.54±0.13 m² in MH 20 mm (n=9), 10.9±4.7 mm Hg and 1.64±0.15 m² in MH 22 mm (n=22), 9.3±3.1 mm Hg and 1.72±0.12 m² in MH 24 mm (n=7). Conclusions: With the exception of the ATS 19-mm valve, the variously sized prostheses have acceptable transprosthetic pressure gradient measurements. In addition, even-sized MH valves (20 and 22 mm) with a thinner sewing cuff showed better hemodynamic performances than similarly sized ATS valves.