[Radioisotope measurement of coronary flow with atrial stimulation in the normal subject and in patients with coronary disease].

The induction of atrial systole by stimulation is a means of demonstrating insufficiency of myocardial perfusion, even where there is a normal coronary flow under basal conditions in a genuine case of coronary atherosclerosis. The method, which entailed the use of radiocardiography with potassium 42, was first checked for reproducibility. The coronary flow was then measured under basal conditions, and subsequently during or after atrial stimulation at 150/min. in a group of 50 controls and coronary patients. Under atrial stimulation, the value increases by an average of 15 per cent in the controls, and decreases by an average of 32 per cent in cardiac patients with vessels which are patent on coronary angiography. The coronary moiety of the cardiac output increases by an average of 27 per cent in the controls, but does not change significantly in the coronary group. After aorto-coronary by-pass, the coronary moiety of the cardiac output is increased significantly during stimulation when the by-pass is patent.