Hemodynamic assessment of Carbomedics bileaflet heart valves by ultrasound: Studies in the aortic and mitral positions

The bileaflet mechanical heart valve has become a]popular prosthesis for implantation in both the aortic and mitral positions and a recent design by Carbomedics has received widespread use, Noninvasive assessment of these valves by Doppler ultrasound is important in characterizing their normal performance and in assessing the course of dysfunction. This study addressed the hypothesis that Doppler predicted pressure drops will correlate with catheter pressure drops within a valve size and position, A subhypothesis is that the pressure drops agree, and we expect this subhypothesis to fail due to pressure recovery effects, In a well-controlled in vitro model it was shown that the combined effects of pressure recovery and neglecting proximal velocities resulted in overestimation of catheter pressure drops for Carbomedics bileaflet valves, Inclusion of the proximal velocity reduced overestimation of peak pressure drops for aortic and mitral valves to clinically acceptable levels, and removed overestimation of mean pressure drops, Without correction for proximal velocity, overestimation of mitral pressure drops was reduced to 3.32% when means were calculated, but mean aortic pressure drops still overestimated the catheter standard significantly, It is concluded that proximal velocities should be included in Bernoulli analysis of Carbomedics heart valves, If the proximal velocity is not available, mitral valves may be best assessed using mean pressure drops, while aortic valve Doppler data, peak or mean, should be interpreted with caution.