Discussion
We present this case report of a severed epicardial atrial lead salvage using an IS-1 lead extender in a 37-year-old patient with Fontan palliation, sinus node dysfunction, recurrent atrial tachycardias and atrial fibrillation resulting in failing Fontan physiology. By salvaging the existing epicardial atrial leads we were able to provide atrial pacing that allowed for rhythm control and marked improvement of his failing Fontan physiology. In this case report we demonstrate how a lead extender can be used to salvage a severed pacemaker lead in patients in need for pacing, in whom implantation of new leads is not promptly feasible due to patient anatomy and/or clinical status. Although our initial intent was to use the IS-1 extension in a bipolar configuration, we were able to retrieve only the anode of the existing leads. We also show that an IS-1 lead extender can be used even if only the anode of a severed lead can be recovered, with adequate unipolar sensing and pacing.
A unipolar extender would have worked in this case as well, however we had planned to attempt a bipolar salvage and did not have a unipolar extender available, Note that with these epicardial leads, the lead body is coaxial bipolar in construction, however it bifurcates into what are essentially two unipolar electrodes that are individually attached to the myocardium (Figure 1C). Although one electrode is used as the anode and electrically connected to the ring of the IS-1, in our salvage procedure we utilized this electrode as the pacing cathode. Yet another option is to use an LV-1 to IS-1 lead adapter. This had the benefit of a much smaller opening at the female end of the adapter, allowing for a better size match between the lead body and the adapter.
The technique that we present here allows for potential salvage of pacemaker leads and avoidance of surgery or complex invasive procedures. Risks of this technique include increased susceptibility of unipolar leads to oversensing and/or adventitious pacing of the diaphragm, chest wall or abdominal muscles. In fact, the insulation breach that we caused in our effort to salvage Lead #2 resulted in forceful abdominal muscle contractions at the energy output required for atrial capture. Furthermore, the long-term durability of the repair that we present here is unknown. For this reason, we do not recommend this technique for patients who are pacemaker-dependent, nor as a sustainable solution for any patient. However, it can be a useful technique for patients whose clinical condition precludes them from being candidates for new lead implantation, and whose condition is expected to improve over time.
The risks, benefits and alternatives must be weighed and presented to all patients in a shared decision-making process. For our patient the alternative to lead salvage was implantation of new epicardial or transvenous leads. However, considering his failing Fontan physiology the risks of these procedures, especially prolonged positive pressure ventilation in the setting of Fontan physiology, were substantial. Due to the brevity of the procedure, the risk of lead salvage was considerably lower, while the benefits could be immediate and significant. We also anticipated that the failing Fontan physiology, which was the main contributor to his operative risk, would improve with rhythm, and atrial pacing and re-establishment of AV synchrony. Last, we want to highlight the important role that the lead manufacturer had in this decision making. Engineers of the lead manufacturer reviewed the lead model, radiographic pictures of the leads, as well as the available connectors and reassured the clinical team that such a repair is feasible.
With improvement in surgical techniques, an increasing number of patients with single-ventricle physiology palliated with Fontan procedures survive to adulthood.6, 7 The median 30-year survival for patients that have undergone Fontan palliation is 43%, (N=1,052).8 90% of patients with Fontan palliation who have survived to age ≥16 will survive at 30 years and 80% at 40 years of age (N=683).6 Patients with Fontan palliation commonly require pacemaker implantation (6-13% of cases2, 6), and in some cohorts pacemaker insertion or revision is the most common reason for re-operation (up to 20% of cases).8 The most common indication for pacemaker implantation is sinus node dysfunction (64% of cases).2 Extensive and multiple surgeries involving placement of intra-atrial baffles contribute to sinus node dysfunction and the need for atrial pacing.1-3 Patients with intracardiac Fontan and double-inlet left ventricles (such as the patient presented in this case report) are more likely to need a permanent pacemaker.2 Other characteristics associated with higher risk for need of pacemaker implantation are mitral atresia, double outlet right ventricle and heterotaxy syndrome.2
Delivering atrial pacemaker leads in patients with Fontan palliation is challenging since, with modern Fontan procedures, the venous circulation is directed to the pulmonary arteries with a conduit, bypassing the atrium. Atrial leads can be delivered epicardially with surgical approaches or, in select cases of intra-cardiac conduits, transvenously with complex interventions that involve puncture of the Fontan conduit.2-5 Case reports are available that describe transvenous lead implantation in patients with extracardiac Fontan conduits.4, 5, 9, 10 Any attempt for transvenous lead delivery in patients with Fontan palliation requires an experienced operator with an in-depth understanding of the patient’s anatomy and the details of previous surgeries. A discussion on transvenous lead delivery in patients with Fontan palliation is beyond the scope of this case report.