Navigating Complex Anatomy During Leadless Pacemaker Implantation

Transvenous pacemakers may lead to wound site complications, such as hematomas and infections. Leadless pacemakers have eliminated these risks. However, when the central venous and/or cardiac anatomy are challenging, their implantation technique may require modification(s). Here, we discuss 3 cases of successful leadless pacemaker implantation in patients with a challenging anatomy. (Level of Difficulty: Advanced.)

LP in patients with difficult anatomy. In this case series, we discuss novel modifications in the technique of LP implantation in 3 different patients with challenging central venous anatomy.

PATIENT 1
A 68-year-old man was referred for extraction of infected pacemaker leads and LP implantation. During implantation, attempts to advance the wire through the inferior vena cava (IVC) were unsuccessful as the wire deviated to the hepatic veins. The LP introducer sheath (IS) was guided to the region of deviation, and a venogram was obtained, which showed selective injection in the hepatic veins with the right hepatic vein draining in the IVC (Video 1).
The IS was withdrawn to a lower level in the IVC, and another contrast injection demonstrated the IVC bifurcating into a medial hypoplastic segment and a lateral shorter and wider continuation further bifurcating into right and left hepatic veins, with the right hepatic vein reconnecting to the IVC at a slightly higher level (Figure 1, Video 2). A glidewire was used to cross the hypoplastic intrahepatic IVC segment to the superior vena cava (SVC). The IS dilator assembly was advanced over the glidewire with the leading dilator, dilating the hypoplastic IVC segment while

LEARNING OBJECTIVES
To discuss the need for variations in the leadless pacemaker implantation technique in patients with complex anatomy including patients with inferior vena cava hypoplasia, inferior vena cava filters, and lumbar scoliosis. To understand the challenges and the possible need for modifications in the leadless pacemaker implantation technique in patients with end-stage renal disease patients on hemodialysis.
meeting moderate resistance, until the IS could reach the right atrial lower border. The LP delivery catheter was then advanced through the tricuspid valve and implanted in right ventricular midseptal position.

PATIENT 2
An 86-year-old woman presented with a left femur fracture sustained after a fall, which was attributed to pauses caused by intermittent complete heart block.  Complex Anatomy in Leadless Pacemaker Implantation J U L Y 1 9 , 2 0 2 3 : 1 0 1 9 1 2 reported case of implantation of LP in a patient with IVC hypoplasia. In that case, a glidewire, which is a softer and easier to maneuver, was used to cross the hypoplastic IVC segment, and the sheath dilator complex were carefully used to dilate that segment.
IVC filters have been considered a contraindication for LP placement, but several successful LP implantations in patients with IVC filters have been previously reported. 4-6 A softer guidewire was typically used to pass through the widest part of the IVC filter, then exchanged for a stiffer wire for successful placement. In case 2, we successfully used a similar technique to cross the IVC filter, despite the added complexity conferred by a significantly tortuous IVC because of severe scoliosis.
Central veins stenosis has been reported to occur in 25% to 47% of patients with end-stage renal disease.
Although central veins stenosis may alter the anatomical course needed for LP implantation, they are preferred over conventional transvenous pacing systems to avoid further exacerbation of the stenosis.
In case 3, the patient had history of right brachiocephalic stenosis that seemed to have progressed to SVC stenosis, which may have contributed to the deformation of the right atrium and displacement of the tricuspid valve in the presence of a severely enlarged left atrium. Successful LP implantation was achieved only after applying a significant counterclockwise rotation to the LP delivery system to be able to cross the anteriorly displaced tricuspid valve.

CONCLUSIONS
With the increasing use of LPs, it is expected that more patients with challenging anatomy will be encountered. In these patients, implantation of LPs is safe and feasible. However, additional tools, implantation technique modifications, and a careful review of additional imaging may be needed for successful implantation.