[Doppler echocardiographic evaluation of the new mechanical bileaflet Sorin Bicarbon valve prosthesis compared with St. Jude Medical]

Despite the Bicarbon valve has been marketed for more than two years, no systematic Doppler evaluation of its normal functioning has yet been published. Therefore, the aims of this study were to establish the normal flow characteristics for the Bicarbon bileaflet prosthetic heart valve and to compare them with those obtained from the St. Jude Medical valve prosthesis.

Doppler echocardiographic characteristics of normally functioning Bicarbon prostheses were prospectively assessed in 76 consecutive patients (44 males and 32 females, mean age 60 +/- 10 years) with 79 valves in mitral (n = 29) and aortic (n = 50) position whose function was considered normal by clinical and echocardiographic evaluation. In addition, Doppler characteristics of the Bicarbon valves in aortic position were compared to those of 27 normal functioning St. Jude Medical implanted during the same period.

For the mitral valve prostheses, we found non significant difference among prosthesis sizes in terms of transprosthetic gradients or pressure half time. Peak and mean gradients were similar in the 27-mm and 31-mm size valves (from 11 +/- 4 to 11 +/- 2 mm Hg and from 5 +/- 2 to 5 +/- 1 mm Hg, respectively; p = NS for both). Similarly, the pressure half time was similar in the 27-mm and in the 31-mm size valve (85 +/- 16 and 76 +/- 13 msec; p = NS). Conversely, for the aortic valve prostheses, there was a significant decrease in transprosthetic gradients and an increase in effective orifice areas as prosthesis size increased. Mean gradient was 13 +/- 1 mm Hg in 19-mm size valves, and it decreased to 6 +/- 2 mm Hg in the 29-mm size. Effective prosthetic valve area calculated using the continuity equation, ranged between 1.0 +/- 0.3 cm2 for 19-mm size valves to 3.5 +/- 0.7 cm2 for 29-mm size. With analysis of variance, effective prosthetic aortic valve area differentiated various valve sizes (F = 23.3; p < 0.0001) better than peak (F = 3.2; p = 0.017) or mean (F = 4.19; p = 0.0035) gradients alone did. Furthermore, effective prosthetic aortic valve area correlated better than peak and mean gradients with prosthetic size (r = 0.87, r = -0.58 and r = -0.57; respectively). In addition, peak and mean transprosthetic gradients and effective prosthetic aortic valve areas did not show any statistically significant difference between the Bicarbon and the St. Jude Medical valves in aortic position, either in 19 and 21 mm (25 +/- 8 mm Hg, 13 +/- 4 mm Hg, 1.3 +/- 0.3 cm2 and 32 +/- 11 mm Hg, 17 +/- 6 mm Hg, 1.2 +/- 0.4 cm2, respectively; p = NS), or in 23 and 25 mm (21 +/- 8 mm Hg, 11 +/- 4 mm Hg, 2.1 +/- 0.5 cm2 and 24 +/- 11 mm Hg, 12 +/- 5 mm Hg, 1.8 +/- 0.4 cm2, respectively; p = NS) or in 27 and 29 mm (12 +/- 2 mm Hg, 7 +/- 1 mm Hg, 2.8 +/- 0.9 cm2 and 16 +/- 5 mm Hg, 7 +/- 2 mm Hg, 2.6 +/- 0.4 cm2, respectively; p = NS).

This study suggest that the Bicarbon valve prosthesis offers relatively little resistance to forward flow except at a small anulus diameter. Furthermore, these is no statistically significant difference between the Bicarbon and the St. Jude Medical in aortic position with regard to early hemodynamic performances.