Study from UPMC Children’s Heart Institute and FORCE Registry Explores Differences in Exercise Performance in Fontan Patients with Extracardiac Conduit and Lateral Tunnel

A multicenter study¹ led by faculty from the Heart Institute at UPMC Children’s Hospital of Pittsburgh examined whether the use of extracardiac conduit (ECC) or lateral tunnel (LT) approaches in Fontan procedures provide superior clinical benefit relative to long-term exercise capacity in patients with single ventricle congenital heart disease.

Findings from the team’s analysis were published in The Journal of Clinical Medicine in June 2025 and represent one of the most comprehensive evaluations on the subject to date using data from the multicenter Fontan Outcomes Registry using Cardiac Magnetic Resonance Examinations (FORCE) registry.

Laura Seese, MD, MS, clinical instructor of Pediatric Cardiothoracic Surgery was the first author of the study. Tarek Alsaied, MD, MSc, FACC, associate professor of Pediatrics was the senior author.

Study Overview and Context

The Fontan procedure is a standard-of-care surgical intervention for patients with single ventricle physiology. Two of the most commonly used techniques to route systemic venous blood flow back to the pulmonary arteries are the lateral tunnel approach, which incorporates native atrial tissue, and the extracardiac conduit, which employs a synthetic tube that is external to the patient’s heart.

While both approaches achieve the same physiologic endpoint, their differences in long-term hemodynamics, arrhythmia risk, and functional outcomes have been an ongoing area of investigation.

Both approaches are well established in the literature, but each has its owns set of risks, challenges, and potential complications. Long-term comparisons of physiologic performance between the two techniques have been limited by small sample sizes or to single-center investigations.

“This study was designed to address an important and recurring question: Does one of these approaches offer a long-term physiologic advantage over the other in terms of exercise capacity?” says Dr. Alsaied. “Some centers prefer the lateral tunnel because it can be performed earlier in childhood and may accommodate somatic growth. At UPMC Children’s, we favor the extracardiac conduit because it is technically simpler and avoids atrial surgery, which has been associated with higher rates of arrhythmia in this population.”

Main Findings

The study used age-matched data from 470 Fontan patients from multiple institutions who also had subsequent cardiopulmonary exercise testing (CPET) data available. While ECC patients performed slightly better on some measures, including heart rate response and oxygenation, both the ECC and LT groups were found to have comparable performance in peak oxygen consumption, which is currently the most important biomarker of a patient’s functional capacity and long-term outcome trajectory.

“The extracardiac conduit group showed some modest differences in intermediate measures, but the overall takeaway is that both Fontan approaches result in similar aerobic capacity by adolescence,” says Dr. Seese. “This suggests surgical choice can be guided by other factors, such as arrhythmia risk or institutional expertise.”

Clinical Implications

The findings from this FORCE registry study may help clinicians and surgical teams reassure families that both Fontan strategies remain viable options from a physiologic standpoint. For institutions that routinely perform the extracardiac conduit operation, the study provides additional support that concerns about conduit size and growth limitation may be less clinically relevant than previously assumed.

“Our data support the continued use of both approaches,” Dr. Alsaied says. “We did not find evidence that the extracardiac conduit impairs exercise performance during adolescence, when concerns about outgrowing the conduit might typically arise.”

A Clear Opportunity for Improving Longitudinal Patient Monitoring

An important finding from this study was the low overall rate of CPET testing in the broader registry population. Fewer than 35% of patients who underwent Fontan surgery after 2000 had CPET data available for analysis. This is despite current guidelines from the American Heart Association that recommend routine CPET every two to three years for patients with single-ventricle physiology and Fontan palliation.

“It’s clear that CPET is an underutilized tool,” Dr. Seese says. “It offers objective insight into Fontan circulation and can help identify patients at risk of decline. Its use needs to increase. I think that is the bottom line when it comes to CPET. We need to do everything we can to educate providers, patients, and families of the importance of this test.”

Reference

1. Seese L, Schiff M, Olivieri L, Da Fonseca Da Silva L, Da Silva JP, Christopher A, Harris TH, Morell V, Castro Medina M, Rathod RH, Kreutzer J, Castrillon CD, Viegas M, Alsaied T, and the FORCE Investigators. Differences in Exercise Performance in Fontan Patients With Extracardiac Conduit and Lateral Tunnel: A FORCE Fontan Registry Study. J Clin Med. 2025; 14: 4067.

Note: Article is Open Access.