Electrocardiographic response to selective coronary arteriography.

Abstract

The ecg changes recorded during the study of 71 patients by selective coronary arteriography are presented. The ecg was monitored continuously during and immediately following contrast injection with warm Hypaque R. The ecg changes common to both right and left coronary artery injection were characterized by a decrease in P wave amplitude, an increase in mean frontal QRS amplitude, an increase in the mean T vector amplitude, and a shift in the mean ST and T vector away from the mean QRS vector. The heart rate slowed and the QT interval increased. The ecg changes of right coronary artery opacification were characterized by a smooth shift of the mean QRS vector to the right and simultaneous shifts of the mean ST and T vectors to the left. These changes were termed right coronary artery response. The ecg changes of left coronary artery opacification were characterized by a smooth shift of the mean QRS vector to the left and simultaneous shifts of the mean ST and T vectors to the right. These changes were termed left coronary artery response. Ecg changes revealing characteristics of both the left and right coronary artery response were noted in 15 patients. These changes were intially those of left coronary artery response and then changed to vector shifts seen in right coronary artery opacification. There were, therefore, 2 major QRS-ST-T vector shifts during selective opacification of 1 coronary artery. Of the 15 patients who demonstrated this response, 14 had evidence of significant coronary arterial obstructive disease. These changes were termed bilateral coronary artery response. Seven of the 15 patients demonstrated prominent collateral flow around the obstructed artery. The 1 patient who did not have evidence of coronary obstruction had calcific aortic stenosis, with a peak systolic pressure gradient across the aortic valve of 145 mm. Hg, and ecg and radiological evidence of left ventricular hypertrophy. The bilateral coronary artery response in 15 patients suggests that contrast medium perfused the myocardium which the artery usually supplies (with the 1 exception noted above), then perfused at least a portion of the myocardium most commonly supplied by the other major coronary artery. The bilateral ecg response to selective coronary artery opacification suggests the existence of intercoronary anastomotic channels.