First‑in‑Infant Extravascular ICD Implantation for Idiopathic Ventricular Fibrillation

A doctor listens to an infant patient's heart with a stethoscope.

First‑in‑Infant Extravascular ICD Implantation for Idiopathic Ventricular Fibrillation

A complex infant arrhythmia case demonstrates how advanced imaging, multidisciplinary expertise, and novel device strategies can expand secondary prevention options beyond traditional epicardial ICDs.

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Key Takeaways

Infants with malignant arrhythmias may now have new implantable defibrillator options that are viable for babies under 40 pounds.
Patient specific 3D planning can determine feasibility below traditional weight limits.
Extravascular defibrillators may reduce morbidity compared with epicardial ICD approaches.
Early referral enables multidisciplinary evaluation before surgical options narrow.

A New Path Forward for Infant Ventricular Arrhythmias

Treating life-threatening cardiac arrhythmias in newborns has long been limited by the lack of implantable defibrillator options small enough, and safe enough, for infants.

Cincinnati Children’s specialists successfully implanted an extravascular implantable cardioverter‑defibrillator (EV‑ICD) in a 6‑week‑old infant with idiopathic ventricular fibrillation (IVF), marking the youngest reported use of this technology. The case illustrates how advanced imaging, virtual surgical planning, and multidisciplinary expertise are expanding treatment options for infants previously only eligible for epicardial ICD implants.

Leveraging 3D Virtual Surgical Planning to Enable Infant EV‑ICD Therapy

Traditional ICD candidacy in infants has been constrained by patient size, anatomy and device design. At Cincinnati Children’s, advanced three-dimensional virtual surgical planning enabled successful EV‑ICD implantation in a 6‑week‑old infant, representing the youngest reported use of this technology for secondary prevention of life-threatening ventricular arrhythmia.

Using CT based imaging, clinicians created a patient specific three-dimensional model of the chest wall, mediastinum and cardiac anatomy within 24 hours. This model was used to evaluate whether a 9‑cm substernal defibrillator lead—typically considered unsuitable for infants—could be safely positioned. By modeling the lead in multiple planes, the team identified sufficient substernal space for implantation, overcoming the limitations of standard two-dimensional imaging.

“This procedure would not have been possible without three-dimensional modeling,” said Chad Connor, MD, pediatric electrophysiologist at Cincinnati Children’s. “Virtual planning confirmed that the lead could safely fit in the substernal space and allowed us to trial multiple positions before entering the operating room.”

This planning strategy builds on Cincinnati Children’s experience adapting adult‑scale cardiac technologies for pediatric use, including ventricular assist devices and complex implantable systems traditionally limited by age or weight thresholds.

Clinical Context: Idiopathic Ventricular Fibrillation in Early Infancy

The patient initially presented at approximately 1 month of age to Cincinnati Children’s Liberty Campus with fever related to a confirmed E. coli urinary tract infection. During hospitalization, the infant experienced sudden ventricular fibrillatory arrest and was successfully resuscitated with external defibrillation.

Following stabilization, the patient was transferred to the Burnet Campus for comprehensive evaluation. Diagnostic testing revealed no structural heart disease, inherited arrhythmia syndrome, medication reaction or infection severity sufficient to explain the event. Ongoing episodes of unprovoked, chaotic ventricular activity supported a diagnosis of idiopathic ventricular fibrillation.

Although rare, sudden cardiac arrhythmias in infancy carry high mortality risk, particularly in the first 6 months of life, when patients may lack identifiable structural or genetic risk factors.

This procedure would not have been possible without three-dimensional modeling. Virtual planning confirmed that the lead could safely fit in the substernal space and allowed us to trial multiple positions before entering the operating room.

Chad Connor, MD

Addressing Device Limitations in Infants

Secondary prevention required implantable defibrillator protection. However, conventional ICD systems are designed for adult anatomy and often require a minimum body weight of approximately 70 pounds. External or wearable defibrillation strategies are not approved for infants; this patient weighed approximately 10 pounds at the time of arrest.

Epicardial ICD implantation via sternotomy was considered but associated with greater procedural morbidity, prolonged recovery, and a high likelihood of repeat open surgeries as the child grows. Published experience suggests complication rates approaching 35% within five years for epicardial ICD systems, even before accounting for multiple future revisions.

Given these risks, the care team pursued an EV‑ICD strategy supported by patient specific three-dimensional feasibility assessment.

Procedure and Early Outcome

After resolution of infection and modest weight gain, minimally invasive EV‑ICD implantation was performed at 6 weeks of age. Using a single sub-xyphoid vertical incision, the pulse generator and battery were positioned in the abdomen in the posterior rectus fascial plane, and a single substernal lead was tunneled through the anterior mediastinum to the left pleural apex.

The patient was discharged six days post‑procedure without complications. Remote monitoring was initiated, resulting in near-continuous device follow-up and reducing caregiver burden.

Compared with epicardial systems, the EV‑ICD approach avoids sternotomy and may reduce long-term morbidity. Lead placement in the anterior mediastinum appears to accommodate somatic growth, and may delay or avoid the need for replacement. While future interventions are anticipated, they are expected to be less invasive than repeat sternotomy.

Implications for Subspecialists and Referral Consideration

This case demonstrates how advanced three-dimensional virtual surgical planning can expand defibrillator options for infants with life-threatening ventricular arrhythmias who fall below traditional ICD candidacy thresholds. For subspecialists managing unexplained ventricular arrhythmias, aborted sudden cardiac arrest, or uncertainty around infant device strategies, early multidisciplinary consultation may reveal additional treatment pathways.

Cincinnati Children’s Heart Institute offers comprehensive evaluations for complex infant arrhythmia cases, including advanced three-dimensional virtual surgical planning to assess device feasibility and procedural risk.

(Published May 2026)

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