CARDIOPULMONARY EXERCISE CAPACITY IN PATIENTS BEFORE AND AFTER PROSTHETIC VALVE-REPLACEMENT

In this study we wanted to investigate if noninvasive cardiopulmonary exercise testing can be securely, accurately applied in patients with acquired cardiac valve disease pre- and postoperatively with any convenience. Furthermore, we looked if the cardiopulmonary exercise capacity (anaerobic threshold, etc.) was improved postoperatively (3 and 6 months) in 15 patients suffering from severe mitral valve disease as compared to the preoperative condition. The symptom-limited cardiopulmonary exercise testing was performed on a bike in a semi-supine position using a ramp program (+ 20 W/min). The following parameters were continuously monitored, and the breath-by-breath gas exchange values documented: cardiocirculatory parameters (heart rate; blood pressure; surface ECG; exercise capacity in Watts); gas-exchange parameters (O-2-uptake VO2; CO2-production VCO2; respiratory anaerobic threshold VO2 AT; gas-exchange ratio VCO2/ VO2; O-2-pulse VO2/HR; aerobic capacity Delta VO2/Delta WR) and ventilatory parameters (respiratory rate; tidal volume Vt; minute ventilation VE; equivalent for O-2: VE/VO2 and CO2: VE/VCO2). The 155 cardio-pulmonary exercise tests in 115 patients were practicable, safe (no emergency case) and accurate. in 100 patients late postoperatively (68.3 +/- 53.0 - 102.9 +/- 41.2 months) after aortic or mitral valve replacement or both without signs of significant hemolysis or prosthetic valve dysfunction the NYHA classification was too imprecise to characterize the actual exercise capacity of the patients (e.g., NYHA class II: Weber class B to E). Patients with aortic valve prosthesis had a significantly better anaerobic threshold (57.4 +/- 19.1 % pred. value max. VO2) as compared to those with mitral valve replacement (mean: 35.9 % pred. value max. VO2). In 15 patients with mitral valve replacement (SJM prosthesis) the NYHA- and respiratory anaerobic threshold was significantly increased from 31.8 +/- 13.2 % to 49.0 +/- 10.7 % pred. value max. VO2 6 months postoperatively. Cardiac and/or pulmonary exercise limitations could be accurately detected in both study groups. In conclusion, the cardiopulmonary exercise testing was found to be an important, convenient, safe, accurate, and practicable non-invasive method to evaluate the exercise capacity in the mostly symptomatic patients with acquired cardiac valve diseases before and after prosthetic valve replacement.