July 22, 2026
Mayo Clinic Cardiovascular Medicine specialists performed a successful transconduit implantation of a leadless pacemaker (LP) into the systemic ventricle of a 61-year-old patient with a lateral tunnel Fontan and chronic liver and kidney disease.
Currently, the most established method of permanent pacing in patients with complex congenital heart disease (CHD) with Fontan physiology is surgically placed epicardial leads. It carries increased perioperative risk, especially in patients with Fontan-associated liver disease and renal dysfunction. Lead failure and threshold elevation are common long-term complications of epicardial pacing. This has led to an interest in minimally invasive alternatives.
Leadless pacemaker implantation offers an alternative for adult patients with Fontan physiology who are not candidates for surgery. This is especially true with the transconduit approach into the systemic ventricle. The details of this implantation were published in HeartRhythm Case Reports.
Rhythm management challenges
Patients with complicated Fontan anatomy present unique challenges in cardiac rhythm management:
- Lack of direct percutaneous venous access to the ventricle.
- Increased venous pressure.
- Elevated thromboembolic risk.
With progressive conduction abnormalities, these patients often require pacemaker implantation.
The appeal of percutaneous implantation of LPs is that they eliminate lead- and pocket-related complications such as infection. Though using the LPs in patients with Fontan circulation remains technically challenging with complex venous anatomy and the lack of direct venous access to the ventricle.
"This report highlights a multidisciplinary effort in providing reliable pacing in a patient who had a failing epicardial pacing system and was not a candidate for repeat surgical revision," says Nicholas Y. Tan, M.D., M.S., a cardiac electrophysiologist in the Heart Rhythm Clinic at Mayo Clinic in Rochester, Minnesota, and senior author of the case report. "Leadless pacemakers in complex congenital heart disease and Fontan anatomy are uncommon and not well studied. Despite the numerous technical obstacles encountered, device performance was excellent immediately postimplant and on follow-up."
Journey to LP implantation
Factors leading up to the decision for LP implantation:
The 61-year-old male patient with Klippel-Feil syndrome and associated CHD, including isolated dextrocardia, double-outlet right ventricle (RV), pulmonary stenosis and hypoplastic RV, underwent a Glenn anastomosis followed by a lateral tunnel Fontan procedure at age 27.
At age 42, he developed complete atrioventricular (AV) block in the setting of permanent atrial fibrillation and underwent epicardial ventricular pacemaker implantation. He had generator changes at ages 46, 51, 54 and 57 years.
The patient presented with a progressive increase in ventricular pacing threshold. Preoperative evaluation demonstrated Fontan-associated cirrhosis and chronic kidney disease.
A multidisciplinary adult CHD team concluded that the patient's surgical risk of epicardial lead revision was prohibitive. After shared decision-making with the patient, transvenous LP implantation was considered.
Procedure details
The report shows potential benefits of transconduit LP implantation in high-risk cohorts, and it highlights technical considerations. There were challenges with access and device selection. "The patient's Fontan repair included the creation of a nonfenestrated intra-atrial conduit. Endocardial pacemaker implantation would therefore require conduit puncture, which is a difficult endeavor especially if it is older and calcified," Dr. Tan says.
For choosing a device, there is a risk of mechanical complications and infection with a transvenous pacemaker. "Additionally, the Fontan repair virtually excludes standard transvenous device placement. A leadless pacemaker was a more attractive option based on the long-term risk profile. We opted for an active fixation mechanism. It allowed us to map and fixate in electrically viable myocardium," Dr. Tan says.
This was a complex procedure that involved multiple personnel across disciplines:
- Anesthesia was carefully managed to avoid cardiopulmonary collapse given the underlying comorbidities.
- The site for conduit puncture was selected to optimize eventual catheter guidance across the right atrioventricular valve into the morphologic right ventricle. Left ventricular implantation was avoided because of a higher risk of systemic thromboembolism.
- Serial dilation with extremely high-pressure balloons was required to open a large enough gap for the leadless pacemaker to be placed.
- The patient's dextrocardia made interpretation of anatomical landmarks more challenging.
- The specialists considered whether the puncture needed to be closed, due to the risks of intracardiac shunting including stroke and desaturation. This was performed the next day.
Looking ahead
There are ongoing efforts to study the use of leadless pacemakers in similar patients. "Larger long-term studies are needed to more clearly understand the efficacy and safety profile of leadless pacing in the congenital heart disease population," Dr. Tan says.
Specialized tools for making access easier will lower the barrier for procedures to be performed more widely. They include:
- Preprocedural or intraprocedural imaging guidance, possibly with augmented reality or artificial intelligence.
- Conduit puncture equipment.
- More-flexible leadless pacemaker delivery mechanisms.
This decision regarding LP implantation should be individualized on a case-by-case basis. "In adult CHD with Fontan physiology, transconduit LP implantation may be considered as an alternative to epicardial pacing in patients at high surgical risk," Dr. Tan says. "With careful imaging guidance and lifelong anticoagulation, it can be safely performed in patients with complex anatomy."
For more information
Vijayakumar K, et al. Transconduit implantation of an active fixation leadless pacemaker in a patient with intra-atrial Fontan palliation. HeartRhythm Case Reports. 2026;12:38.
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