DISCUSSION
Stenosis of the SVC baffle occurs in up to 40% of patients treated with
the Mustard procedure, with risk factors including a Dacron baffle, a
tortuous baffle course, baffle leaks, and a young age at
operation.1,2,4,5 With the increase in permanent
pacemaker insertion in this patient population, transvenous lead
placements across the baffle may increase stenosis rates to up to
58%.1,3 Baffle stenosis can lead to severe
complications, such as persistent hemodynamic load, hypoxia,
thromboembolic events, and SVC syndrome, requiring
re-intervention.3
Transcatheter interventions have been the preferred therapeutic option
in transvenous lead extraction and relief of baffle obstructions,
including laser lead extraction or radiofrequency perforation followed
by angioplasty and stent placement.2-4,6,7 Laser lead
extraction uses pulsatile ultraviolet light to dissolve fibrous tissue,
whereas radiofrequency perforation uses rapid
heating.6-8 However, both methods are associated with
risks of cardiac wall perforation and damage to surrounding structures
or the conduction system.6,7
In adult congenital heart disease (CHD), use of the mechanical rotating
dilator sheath is an evolving treatment strategy to minimize the risk of
bleeding, trauma to surrounding structures, and death. The baffle
stenosis is typically more compliant than native tissue stenosis.
Therefore, great diligence is required with the mechanical rotating
dilator sheath to avoid over-dilation and puncture through the baffle
wall.2 Intraprocedural angiography aids in guiding
dilatation and maintaining safety. Complete transvenous lead extraction
in CHD patients has been successful in up to 92% of patients in prior
studies, with failures attributed to calcified adhesions or active
fixation.3,6,9,10 In our case, we recognized the risks
associated with completely removing the nonfunctional LA lead.
Therefore, extraction was halted.
A second benefit of using the mechanical rotating dilator sheath was its
ability to fully alleviate the SVC baffle stenosis. A stent may not have
been necessary after attempted lead extraction in this case due to the
low gradient shown after adhesiolysis alone. However, recognizing that
delaying baffle stenting may lead to rapid thrombosis, especially after
extensive adhesiolysis, we continued with deployment of the
balloon-expandable stent.3 Optimal stent placement is
crucial for future pacemaker lead placement, which may be necessary in
the case of this patient, as well as the benefits of decreased baffle
gradients, increased baffle diameter, relief of clinical symptoms, and
delay of the need for re-intervention.2
A multi-disciplinary team approach including an interventional
cardiology, electrophysiology, and cardiothoracic surgical team that are
familiar with adult CHD is crucial in managing these complex cardiac
cases safely. Prophylactic measures are taken to avoid complications,
such as intubation, full sedation, and placement of a transesophageal
echocardiogram (TEE) probe. During the procedure, obtaining access from
the bilateral femoral arteries and veins allows for accurate
localization of the baffle from above and below, as well as continuous
imaging during stent placement.2 Further, obtaining
access for emergent bypass and placing a sheath and balloon in the right
internal jugular vein for emergent tamponade are necessary in procedural
planning, as the periprocedural mortality rate for baffle-related
re-intervention can be as high as 29%.2,5,11Additionally, the extent and timing of anticoagulation is pre-planned to
avoid excessive bleeding throughout the course of the combined
procedure.