Case Study: LV Lead Revision Due to Diaphragmatic Stimulation

In this article, author Dr. Tran presents a case study where cardiac venous anatomy limited the options for biventricular pacing therapy. Dr. Tran discusses utilizing an active fixation lead to replace the previous LV lead and return biventricular therapy to his patient. Case Presentation A 56-year-old athletic man presented to the electrophysiology (EP) lab for a left ventricular (LV) lead revision due to diaphragmatic stimulation. The patient had a history of atrial fibrillation and intermittent atrial flutter. In the late 1990s, he underwent a reportedly difficult atrial flutter ablation in Illinois. He subsequently had a single-chamber pacemaker followed by an AV node ablation at that time. In 2000, the RV lead fractured and the patient had an upgrade to a dual-chamber pacemaker, as he was found to be in sinus rhythm at that time. Three years ago, he had recurrent atrial flutter and atrial fibrillation; subsequently, an atrial fibrillation ablation was attempted at a different institution in Arizona that was complicated by tamponade requiring rescue surgery. The patient continued to have persistent atrial fibrillation with intermittent atrial flutter on his ECGs, and his echo showed an ejection fraction (EF) of 40%. Two months ago, this patient had an upgrade to a biventricular pacemaker due to his congestive heart failure symptoms, but diaphragmatic stimulation post-procedure necessitated that the LV lead be turned off. Consequently, the patient was feeling more fatigue and shortness of breath due to right ventricular (RV)-only pacing. Discussion When the original LV lead was placed two months prior, the cardiac venous anatomy was non-existent. Post-venogram, there was one lateral branch in which to place the original LV lead. The lateral branch had a tortuous take-off that was extremely difficult to access. Multiple 0.014 wires (Whisper, Platinum Plus, Choice PT, Boston Scientific, Natick, MA) were used with little success staying in the branch when a lead was advanced over the wire. The branch could only be reached and maintained utilizing the Attain Select II subselector (Medtronic, Inc., Minneapolis, MN) through the coronary sinus (CS) cannulation catheter. The Attain Select II subselector was unique in that it provided the support of an inner catheter and could deliver a 4 French lead. After several hours trying to access the lateral branch, this option was the only one that ended up being successful. The lead was advanced to the distal end of the branch over a wire through the subselecting catheter. During testing of the lead, the distal placement demonstrated diaphragmatic stimulation even at a very low voltage. It was decided to pull the lead back slightly in the branch to try and avoid the phrenic nerve. The more proximal position provided an adequate pacing threshold of 1.2 V @ 0.5mS, and the diaphragmatic stimulation threshold was at a higher voltage of 8V @ 0.5 mS. During a follow-up visit two weeks later, the patient presented with diaphragmatic stimulation that could not be programmed around and provide adequate pacing in the LV for the patient. A chest x-ray confirmed that the lead had migrated more distal into the vein. The decision was made to turn off the LV lead and provide only RV pacing to the patient. Because the patient was highly active, this new programming was very detrimental to his daily physical activities. When he returned to the office complaining of not feeling well, the decision was made to revise his LV lead utilizing the new Medtronic StarFix lead. It was felt that the StarFix lead could be fixated in an exact location of the one lateral vein the patient had, and would prevent migration and consequently phrenic nerve stimulation. Procedure When the patient arrived at the EP lab for the procedure, all the leads appeared structurally intact. The original LV lead was removed without any complication. A CS sheath was advanced to the mid CS. A CS venogram showed a medium CS with a very small posterior and the same small high lateral branch that the original LV lead was placed. A Whisper wire (Boston Scientific) was used to cannulate the high lateral vein. The StarFix was advanced directly over the wire to a very distal portion of the high lateral vein. Once again, in this distal position, diaphragmatic stimulation was present. The lead was pulled back to a more proximal position located in the high lateral vein showing no diaphragmatic stimulation when pacing the lead at 10.0 V output. The patient was asked to take deep breaths and cough to confirm no diaphragmatic stimulation. The lead was then actively anchored to this position by deploying the lobes of StarFix. The Whisper wire was then pulled into the body of the lead and the CS-EH was removed with the slicing tool. Because the CS ostium was tortuous, there was some tension transferred to the lead during slicing; however, the lead did not budge. The LV StarFix Model 4195 lead (88 cm) had final R-waves of 6.5mV, a pacing threshold of 1.1V @ 0.5 mS and an impedance of 909 Ω. Figure 1 shows the final placement of the lead in the high lateral branch. The StarFix lead has radio-opaque indicators that move together to demonstrate lobe deployment, and as seen in Figure 1, these indicators (as seen inside the circle) each show a slightly different spacing. As the four indicators move together, they represent each of three fixation lobes being deployed. The tighter spacings represent greater lobe deployment in the vein. The most proximal (furthest left) spacers show complete deployment of the proximal lobe as it is in the widest part of the branch as it turns the corner and then starts to narrow down. The most distal lobe had minimal deployment as it wedged into the narrower section of the vein (see the wider spacing between right two indicators). The middle lobe was partially deployed as it entered the section of the vessel that was gradually narrowing. Conclusion The patient presented to the office for his two-week follow-up with no repeated diaphragmatic stimulation and feeling much better. The StarFix lead was the only option for this patient since it maintained its position in a vessel where other leads could not. The only other options were to deny the patient LV pacing or send the patient for an epicardial lead placement, both of which come with either lower quality of life or infection. As a result of our success, a pacemaker-dependent patient is benefitting from biventricular pacing, feeling better, and is able to return to his normal activities.