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.