Cardiovascular Mechanisms of Functional Aerobic Impairment in Patients with Coronary Heart Disease

Maximal oxygen uptake VO2max) and functional aerobic impairment (FAI) were determined by treadmill test in 42 men with coronary heart disease and in 11 slightly older healthy men. Patients were separated according to occurrence or nonoccurrence of angina with exercise. At rest and at four levels of submaximal exercise on a bicycle ergometer, cardiac output (Q), using the direct Fick principle, heart rate (HR), mean systemic and pulmonary arterial pressures, and arterial-mixed venous oxygen difference (A-V O2 D) were evaluated in relation to relative aerobic requirement (% Vo2max). Q was highly correlated with Vo2, and both the level and the rate of change of Q were lower in patients with angina at all submaximal workloads. Stroke volume (SV) and HR were significantly restricted at the higher workloads. Although peripheral resistance was increased, there was no compensatory increase in A-V O2 D. Both restricted SV and reduced HR are responsible for cardiovascular components of the abnormal FAI found in patients with myocardial ischemia due to coronary arterial disease.