Modified Hemi-Fontan Procedure

Abstract

Staged palliation for neonates born with hypoplastic left heart syndrome (HLHS) and other single ventricle heart defects has provided a viable form of treatment with everimproving short- and long-term outcomes. The second-stage palliation for single ventricle heart defects, the hemi-Fontan, or bidirectional Glenn operation removes the volume overload on the ventricle from the systemic shunt. The incorporation of an early superior cavoplumonary connection to remove the deleterious effects of volume overload has dramatically improved long-term ventricular function in this patient population and is thought to be one of the largest contributors to improved outcomes in the modern era of staged palliation. Important components of this procedure include creating an unobstructed connection from the superior vena cava (SVC) to the pulmonary arteries (PAs) to provide adequate pulmonary blood flow, augmentation of the central PAs to remove any potential stenosis, avoidance of conduction disturbances, and anticipating the future connection of the inferior vena cava (IVC) to the PAs. Our technique differs from the original hemi-Fontan description 1,2 with 2 modifications. First, the incision on the right atrium is limited to the right atrial appendage and is therefore not carried onto the SVC. This minimizes the risk of transected the artery to the sinoatrial node, and we have demonstrated that this has reduced short- and long-term arrhythmias. 3 Second, the homograft patch augmentation is limited to the central PAs and a separate polytetraflouroethylene (PTFE) patch is utilized to exclude the SVC return from the right atrium. This simplifies the reestablishment of this connection while performing Fontan procedure. At the University of Michigan, the hemi-Fontan is preferred over the bidirectional Glenn as the second-stage operation of choice for patients with amenable anatomy. The reasons for this preference include the ability to correct any potential risk factors for poor long-term outcome such as PA distortion due to the systemic shunt, the maintenance of a stable circulation free of right ventricular volume overload, and the creation of a large eventual pathway for connection of the IVC to the PAs. The volume-unloading second-stage palliation for single ventricle cardiac lesion is generally performed at 4-6 months of age. The timing of surgery is dependent on the patient’s saturations, somatic growth, and need for intervention for associated defects, such as progressive tricuspid valve regurgitation. Preoperative cardiac catheterization is performed to evaluate right ventricular function, tricuspid regurgitation, residual arch or atrial septal obstruction, branch PA anatomy, and pulmonary vascular resistance. The hemi-Fontan procedure is certainly more complex than the bidirectional Glenn, but the routine augmentation of the branch PA associated with our technique of the hemiFontan ensures optimal PA anatomy and the effort dramatically simplifies the ultimate Fontan procedure. In addition, by performing a more complex operation at the time of stage 2 rather than at the Fontan procedure when the postoperative hemodynamics are more demanding, the postoperative course can be optimized as well.