[Doppler technics in the study of prosthetic valves].

The authors studied a group of 120 patients and a total of 137 valvular prostheses by ultrasonic pulsed Doppler (3 MHz). Fifty three of these prostheses were also investigated with continuous wave Doppler. Clinical, phonocardiographic and echocardiographic examination revealed 99 normal and 38 abnormal prostheses, the latter group comprising 42 dysfunctions (9 obstructions and 33 regurgitations), all confirmed by invasive studies. The lesions were graded into 3 degrees of severity. The methods used were the recording of velocity signals and two- and three-dimensional mapping in the pulsed Doppler mode, and the calculation of the haemodynamic parameters derived from measurements of blood velocity in the continuous wave mode. Pulsed Doppler correctly diagnosed 92 out of the 99 normal prostheses. The maximum systolic pressure gradient in aortic valve prostheses was 16 +/- 6 mmHg; the average early diastolic pressure gradient of the mitral valve prostheses was 10.01 +/- 3.34 mmHg, with a mean diastolic gradient of 4.52 +/- 0.71 mmHg and a mean pressure half time of 0.09 +/- 0.02 sec giving an average valve surface area of 2.45 +/- 0.57 cm2. The sensitivity and specificity of the diagnosis of valve dysfunction were 95 and 92 per cent respectively with a satisfactory evaluation of the degree of severity in 88 per cent of cases. In the 3 mitral valve prostheses with obstruction, significant abnormalities of pressure half time and value surface area were detected.(ABSTRACT TRUNCATED AT 250 WORDS)