Inadvertent left ventricular pacing through a patent foramen ovale diagnosed by trans-thoracic echocardiography.

Abstract

A trans-thoracic echocardiogram was performed to monitor the progression of aortic stenosis in an 87-year-old lady who had undergone permanent pacemaker insertion 4 months previously for symptomatic sinus bradycardia. The apical four-chamber view (Fig. 1, supplementary video) revealed that the ventricular lead (v-lead) had passed through a patent foramen ovale (PFO) and was fixed to the lateral left ventricular wall. A pacemaker check confirmed right bundle branch block (RBBB) morphology during VOO mode pacing (Fig. 2). The patient was advised to consider anticoagulation in the short term and repositioning of the v-lead at the time of aortic valve surgery as definitive therapy. However, she declined surgical intervention and is currently on long-term anticoagulation. Inadvertent left ventricular pacing may arise from the v-lead traversing a previously undetected PFO or perforation of the ventricular septum during implantation [1]. The major complication of LV pacing is systemic thromboembolism within days or years later [2] which prompts the standard recommendation of lead extraction and repositioning in such patients. However, a case series of patients who have undergone intentional endocardial LV pacing suggests that anticoagulation [international normalized ratio (INR) 2.5–3.5] provides adequate protection from thrombo-embolic events [3].