[Hemodynamic testing at rest and during exertion after mitral valve replacement with a St. Jude Medical prosthesis]

177 mitral valve replacements with the St Jude Medical prosthesis (SJM) were carried out from March 1979 to December 1983. 45 of these patients (22 men and 23 women) underwent right heart catheterisation 6 or 8 months after surgery. These patients were operated for pure mitral stenosis in 24 cases, mitral regurgitation in 10 cases and mixed mitral disease in 24 cases. There was associated aortic valve disease in 26 patients and valve replacement with a Björk prosthesis was carried out in 19 cases. Tricuspid valvuloplasty was performed in 6 patients. 37 patients were at Stage III or IV of the NYHA classification before surgery; one year later, only 1 patient remained at Stage III, 4 patients were at Stage II and 38 at Stage I. 2 patients died in the first postoperative year of extracardiac causes. Resting pulmonary capillary pressure (Pw) fell from 18 +/- 7 mmHg to 9 +/- 4 mmHg after surgery (p less than 0.001); cardiac index rose from 2.21 +/- 0.45 to 2.59 +/- 0.49 1/min/m2 (p less than 0.001). A capillary arteriolar obstruction observed in 16 patients before surgery was only found in 9 of these patients after surgery. The changes in pulmonary pressures and cardiac output during exercise were studied in 22 patients. Pw rose from 7.6 +/- 1.5 mmHg to 20 +/- 4 mmHg; cardiac index increased from 2.62 +/- 0.19 to 5.46 +/- 0.72 1/min/m2. When compared with theoretical results in a normal subject, pulmonary artery pressures were abnormally high in 13 subjects (59 p. 100), reflecting a stenosing effect of the prosthesis, unmasked by exercise.(ABSTRACT TRUNCATED AT 250 WORDS)