Doppler echocardiography in prosthetic valve dysfunction. Diagnostic value in twenty cases

We performed a retrospective study of 20 cases of prosthetic valve dysfunction which required reoperation and in which preoperative Doppler studies were performed. There were 13 mitral (3 mechanical, 10 bioprostheses) 5 aortic (1 mechanical and 4 bioprostheses), 1 pulmonary bioprosthesis and 1 mechanical tricuspid valve dysfunction. The aim of the study was to establish the diagnostic value of the Doppler examination by comparing the results with the operative findings. The parameters measured were: peak pressure gradient and mean pressure gradients in all prostheses, together with pressure half times and functional surface area in mitral and tricuspid valve prostheses. Cardiac catheterisation was performed in 6 cases before surgery. The diagnosis of prosthetic valve obstruction was correctly made, even in the 1 case with moderate stenosis. All cases of regurgitation were diagnosed and the topographical location of the leak was identified, except in 1 mechanical mitral valve prosthesis in which the regurgitant jet was detected only by continuous wave Doppler. Fourteen of the 20 cases were reoperated upon without catheterisation. These results suggest that Doppler echocardiography is a sensitive and specific diagnostic method of assessing prosthetic valve dysfunction. However, as the Doppler parameters are variable from one prosthesis to another, it is important to perform pulsed and continuous wave Doppler baseline studies in the immediate postoperative period as a reference in case of suspected valve dysfunction at a later stage.