Haemodynamics and myocardial metabolism in patients with obliterative coronary arteriosclerosis and tachycardia induced by pacing.

Fifty-three men with significant obliterative arteriosclerosis of coronary arteries were examined at rest, during and after pacing. Pacing induced both angina pectoris and depression of the ST segment in 38% of the patients; either angina pectoris or depression of ST segment, in 32% of the patients; the remaining 30% of patients were without symptoms or ECG signs of coronary insufficiency. Haemodynamic findings at rest, or during and after cessation of pacing were not different between these groups. Pacing increased heart rate, cardiac index remained unchanged, the stroke volume decreased, the left ventricular ejection time shortened. In both systemic and pulmonary arteries the systolic pressures decreased, the diastolic and mean pressures rose. The left ventricular end-diastolic pressure decreased. In 28 of the patients the myocardial metabolism was investigated. A close correlation was found between positive symptoms and ECG signs of myocardial ischaemia on the one hand, and metabolic signs on the other hand. Absence of angina pectoris and depressions of the ST segment during pacing does not exclude the presence of metabolic signs of ischaemia; an opposite finding is about three times less frequent. The study offers objective information about haemodynamics and myocardial metabolism before, during and after pacing, and represents an attempt of a simple classification of symptoms and signs of induced ischaemia.