Cardia venous blood flow in atrial pacing versus exercise-induced angina pectoris.

Thirteen patients with angina pectoris underwent measurements of great cardiac vein blood flow at rest, with the onset of angina pectoris induced by atrial pacing, and again during angina pectoris induced by exercise in order to compare the regional coronary blood flow response to differing myocardial stresses. All patients had significant obstructions of the left anterior descending artery. Exercise-induced angina, compared to pacing-induced angina, was associated with a higher systolic pressure, higher left ventricular end-diastolic pressure, and a lower heart rate. Indices of myocardial oxygen demand, that is, the systolic pressure-heart rate product and the tension-time index, increased to a similar degree during both types of myocardial stress and great cardiac vein blood flow paralleled these changes. We conclude that in a given patient the level of regional coronary blood flow is similar at the onset of either pacing- or exercise-induced angina, despite significant differences in the hemodynamic response to these myocardial stresses.