title: Unusual electrocardiographic pattern during transvenous pacing from the middle cardiac vein.
abstract: This report documents the unusual occurrence of a left bundle branch block pattern of ventricular depolarization during permanent pacing from the middle cardiac vein. All previous reports of ventricular pacing from the middle cardiac vein have described a right bundle branch block pattern of ventricular activation (dominant R-waves in the right precordial leads), except in one case where both right and left bundle branch block patterns occurred at separate times. A high posterior infarct allowed early activation of the right ventricle from the middle cardiac vein. Undue reliance on the electrocardiogram may detract from the diagnosis of electrode malposition.
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000175:diagnosis*; D002304:Cardiac Pacing, Artificial; D003331:Coronary Vessels; D004562:Electrocardiography; D004567:Electrodes, Implanted; D006801:Humans; D008297:Male