3. DISCUSSION
Epicardial pacing has been a regular option for patients with complex
congenital heart disease. Epicardial leads may be placed during cardiac
surgery for underlying congenital heart disease with a plan to replace
them in the future with transvenous leads.4Endocardial pacing of the ventricle for patients with Fontan circulation
was impractical due to the lack of transvenous access to the ventricle.
With the advances in pacing techniques, ventricular pacing in these
patients is possible. Hsieh et al. reported permanent pacing of the left
ventricle via coronary sinus in a patient with Fontan circulation and
complete atrioventricular (AV) block.6 In another case
report of a single ventricle patient using the endocardial method,
DeWitt et al. described successfully placing a ventricular pacing lead
through a trans-Fontan-baffle puncture.7 These
techniques may be good alternatives to high-risk epicardial pacing
methods in this group of patients.
Endocardial ventricular pacing is technically possible in patients with
univentricular hearts who have not had previous reconstructive surgery,
but the higher risk for thromboembolism limits this
procedure.2 In a cohort study of 202 patients,
transvenous pacemakers increased the risk of systemic thromboembolism in
patients with intracardiac shunt by >2-fold, and
anticoagulant therapy with warfarin or aspirin did not reduce the
risk.3 However, when the risk of the surgery for
epicardial lead placement is high transvenous route may be the better
choice. This case was a candidate for a Fontan procedure with epicardial
lead placement, but this was a high-risk procedure considering his
chronic high pulmonary artery pressure. As a result, we deemed that
transvenous lead placement with a tight anticoagulant regimen is the
option with the lower risk. According to our research, this is the
second report of left ventricular endocardial pacing via the interatrial
septum in a single ventricle patient. In a similar study, Scott et al.
reported a case of tricuspid atresia with intracardiac shunt and
symptomatic chronotropic incompetence. They implanted an endocardial
pacemaker in his left ventricle through the atrial septal defect to
improve his condition. The patient had no thromboembolic events or
complications related to the procedure at the one-year
follow-up.8
There are few studies comparing the outcomes of dual-chamber pacing
versus single-chamber ventricular pacing in patients with single
ventricle physiology. Nevertheless, dual-chamber pacemakers are
generally considered in these patients because of atrioventricular
synchrony, which enhances cardiac output and the capacity to interfere
if atrial arrhythmia or sick sinus syndrome occurs.9
The bilateral perirenal fluid accumulation was a rare finding in the
present case. It has been reported in cases with intracardiac shunt and
pulmonary hypertension.10,11 Pentimone et al. proposed
that the underlying mechanism is that pulmonary hypertension increases
local hydrostatic pressure in the perirenal veins, leading to fluid
leakage to the renal subcapsular space. In their case repeated
phlebotomies lowerd hematocrit and reduced perirenal fluid
significantly.10
In conclusion, while endocardial pacing, in the presence of intracardiac
shunts, has the risk of systemic thromboembolism, it may be the safer
alternative for epicardial interventions in selected patients.