The Genesis of QRS Changes Produced by Selective Coronary Arteriography

Selective coronary arteriography produces characteristic ST-T changes associated with significant axis shifts. In patients with normal control AQRS (mean, +88.60; SD-t- 12.20) left coronary injections induced an important leftward deviation of the AQRS: mean, +8.2.; SD, +49.10 (P < 0.001). Right coronary artery opacification changed the AQRS from a control mean of +66.50; SD, +17.20 to a mean of 89.3°; SD, +16.70 (P < 0.001). Left axis shifts after left coronary artery injections were significantly more marked than right axis deviation after right coronary injections. Important increases (beyond 0.02 sec) in ventricular activation time were not observed. These electrocardiographic abnormal-ities were attributed to the transient ischemic or toxic effect produced by the bolus of dye. This could result in different degrees of complete or incomplete block in the divisions of the left branch or in an extensive peripheral block affecting large areas of the subendocardial regions of the heart. Additional Indexing Words: Block in the superior division of the left br. Block in the inferior division of the left bra S ELECTIVE opacification of the coronary arteries is accompanied by significant translent electrocardiographic changes.1-These include variations in rate, P and T-wave axis, P-R intervals, Q-T and S-T segments, and changes in the mean QRS axis. The genesis of repolarization abnormalities occurring during coronary arteriography has been properly analyzed in previous studies.'-8 However, knowledge regarding the existence and mech-anisms of depolarization changes is not so widespread. The purpose of the study is to emphasize the importance of QRS changes produced during this procedure and to discuss the probable mechanisms of production