Seventy-one patients undergoing valve replacement surgery were studied before and after operation to determine change of clinical condition and ventricular contractility. Preoperatively, all patients had functional class III or IV disease (New York Heart Association classification) and 55 percent had myocardial dysfunction. Post-operatively, the condition of 86 percent of patients improved clinically by at least 1 functional class, but 56 percent of patients had myocardial dysfunction. Cardiac index and left ventricular end-diastolic pressures were closely related to changes in angiographically determined myocardial contractility. Neither patient age, sex, duration of cardiopulmonary bypass, residual uncorrected valve disease nor coronary artery disease alone determined the degree of impairment in left ventricular contractility. A high incidence of myocardial dysfunction was found pre- and postoperatively in this study. In 16 patients with pure mitral stenosis, 6 (38 percent) had left ventricular dysfunction preoperatively, demonstrating intrinsic myocardial disease, possibly chronic rheumatic myocarditis. The demonstration of postoperative myocardial contractile abnormalities in previously normal patients suggests an intraoperative cause, perhaps related to cardiopulmonary bypass. Postoperative dysfunction may (1) exist preoperatively and remain unchanged, (2) occur intraoperatively, or (3) exist in a latent form preoperatively but be aggravated by the stress of surgery. Without both pre- and postoperative microscopic examination of the myocardium in the same patient, it is impossible to determine which process is primary.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine