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.