[The significance of electrocardiogram in the estimation of correct lead position in patients with permanent ventricular pacing].

Transvenous pacemaker lead malposition in the left ventricle is a rare complication of pacemaker implantation however, at the moment of diagnosis poses the serious therapeutic problem. The usual morphology for paced events originating from the right ventricle has a left bundle branch block pattern, but sometimes right bundle branch block (RBBB) configuration is identified. The report describes two cases of RBBB configuration in the electrocardiogram (ECG) after pacemaker implantation. Case 1 demonstrates a female with unintentional pacemaker lead placement in the left ventricle through patent foramen ovale. Lead malposition was diagnosed accidentally during echocardiographic study (ECHO), 6 years after implantation. Case 2 concerns a man with a RBBB pacing configuration, but with correct pacemaker lead position in the right ventricle. Authors analyze these cases in connection with other publicized reports in order to find the safe algorithm for intraoperative estimation of correct pacemaker lead location. The following algorithm of procedures during pacemaker implantation is proposed to avoid the lead malposition in the left ventricle. First, obligatory perform 12-lead ECG in pace mode during surgery or immediately after it. Second, in case of RBBB pattern in post implant ECG, make ECHO for precise lead position description.