Influence of right ventricular ischemia on septal Q waves determined by coronary angioplasty.

The aim of this study is to evaluate the influence of right ventricular ischemia on the amplitude of septal Q waves. Twenty-two patients without previous myocardial infarction who underwent isolated right coronary artery angioplasty were studied. The criterion for right ventricular ischemia was defined as ST elevation of 0.1 mV or more in lead V4R during angioplasty. The patients were divided into two groups: those with (group A, n = 12) and those without (group B, n = 10) right ventricular ischemia. There was no significant difference in the amplitude of septal Q waves in any lead before angioplasty between the two groups. During angioplasty, group A showed a reduction in the amplitude of septal Q waves in leads V5 and V6 but no change in the amplitude of septal Q waves in leads I and aVL. Group B had no significant reduction in the amplitude of septal Q waves in any lead. During angioplasty group A had a higher incidence of reduction of at least 0.05 mV of the septal Q wave amplitude in any lead (58% vs 10%). These results indicate that the amplitude of septal Q waves is occasionally reduced by right coronary occlusion and most such cases are accompanied by right ventricular ischemia. Therefore reduction of the amplitude of septal Q waves during right coronary occlusion appears to be caused by reduction of the electrical force derived from the right ventricular myocardium.