Troubleshooting in the EP Lab: Interesting Cases at the Oklahoma Heart Institute

In this article, the authors highlight two brief case studies from the Oklahoma Heart Institute. Case #1: The Natural CRT In 2003, a 55-year-old female presented to the Oklahoma Heart Institute with syncope and high-degree AV block (Figure 1A). A dual chamber pacemaker was placed without incident. Five years later, during a routine transtelephonic pacemaker transmission, pre-excitation was noted (Figure 1B). Upon evaluation, the patient admitted to intermittent palpitations and was referred for EP testing. During EP testing, a left-lateral accessory pathway with anterograde conduction was clearly evident as well as complete infra-nodal AV block. There was no evidence of retrograde conduction over the AV node or accessory pathway nor any inducible supraventricular tachycardia, despite isoproterenol infusion. The pathway ERP was 240 ms when pacing at 400 ms. The shortest preexcited RR interval during induced atrial fibrillation was 300 ms. Based on these findings, we concluded that the pathway: 1) was not implicated in any tachycardia, 2) posed low risk of sudden death during atrial fibrillation, and 3) was the patient’s sole means of conduction should pacemaker failure occur. Therefore, a decision was made to forgo catheter ablation. Furthermore, we chose to optimize her pacing by adjusting her “RV-LV” delays. Numerous ECGs were performed at various AV delays. The narrowest QRS complex was achieved with an AV delay of 100 ms (Figure 1C). This case illustrates the use of a dual chamber pacemaker for cardiac resynchronization therapy (CRT) using a manifest accessory pathway for LV activation. This case also underscores the importance of assessing underlying AV conduction prior to performing catheter ablation of accessory pathways, as the pathway may be the sole source AV conduction. Case #2: Balloon Trick for LV Lead Delivery A 65-year-old male with a severe ischemic cardiomyopathy was admitted to the Oklahoma Heart Institute with an acute exacerbation of congestive heart failure. Echocardiography demonstrated an ejection fraction of 15%, and an ECG demonstrated sinus rhythm with a left bundle branch block. The patient had initially undergone ICD implantation in 1998, and had new right atrial and right ventricular leads added in 2003. Once his heart failure was stabilized, he was referred for upgrade of his dual chamber ICD to a biventricular ICD. Coronary sinus (CS) venography demonstrated an ideal lateral cardiac vein, albeit with an acute take-off (Figure 2A). Guidewires could easily be passed into the vein; however, a lead would only prolapse into the main body of the CS (Figure 2B). When confronted with such a situation, there are a few options: 1) utilize the “buddy wire” technique for added distal support and straightening of the vessel; 2) use a directional inner sheath for added proximal support; 3) try a new lead; 4) anchor the wire with an angioplasty balloon placed distally in the vein;1 or 5) refer for a surgical epicardial approach. Initially we attempted the “buddy wire” technique by adding a second 0.014” wire side-by-side; however, there was still not enough stability to advance the lead. A second lead also prolapsed due to lack of distal support. We then recanulated the coronary sinus with a second sheath and placed a venography balloon distal to the vein take-off. Once inflated, the balloon prohibited the lead to prolapse as it was advanced in the vein (Figure 2C). A chest x-ray and ECG demonstrated ideal lead placement with narrowing of his QRS (Figures 2D and 2E). One year later, the patient remains free of heart failure symptoms. This case illustrates a novel approach to lead delivery past an acute take-off. This trick can be added to the bag of tricks employed by the electrophysiologist during difficult CRT implantation.