Evaluation of the Cardiopulmonary Exercise Tolerance in Patients with Coronary Artery Disease (CAD) and Chronic Heart Failure (CHF)

Summary

The O₂-uptake at the anaerobic threshold ( $\dot V$ O₂ AT), as detected by gas exchange measurements during an incremental exercise test on a semi-supine bicycle, is an objective parameter for the estimation of cardiopulmonary exercise capacity. It was used to assess the severity of cardiopulmonary and cardiovasculary diseases in patients with coronary heart disease (CAD, N = 22, mean age 54.05 ± 7.88 years) and chronic heart failure (CHF, n = 15, mean age 57.73 ± 12.61 years). According to $\dot V$ O₂ AT, we found a high distinction between the subjective and the objective evaluation of exercise capacity, using the Weber- and the NYHA-classes. The NYHA-classes provide insufficient criteria for exercise capacity (i.e. 14 CAD-patients NYHA II were individually assigned to very different Weber-classes: 2/14 Weber A, 2/14 Weber B, 4/14 Weber C, 5/14 Weber D, 1/14 Weber E). Our investigations showed that the O₂-uptake of every pedaled watt (Δ $\dot V$ O₂/ΔWR) should be a parameter to estimate the exercise capacity, but seems to be very insufficient in patients with severe heart failure and low values of maximum work rate (WR). Oscillations of the respiratory variables during rest, exercise, and recovery were reported in 4/22 CAD-patients (18.2%) and in 9/15 CHF-patients (60%). A constant value for O₂-pulse, the O₂-uptake of every heart beat ( $\dot V$ O₂/HR), was reached in 10/ 22 CAD-patients (45.5%) and in 8/15 CHF-patients (53.3%). The computerized ergospirometry is a feasible, secure, accurate, and well-tolerated method to objectively evaluate the functional disability of patients with CAD of CHF. The present study offers new insights in the evaluation of critically ill patients using non-invasive procedures.