Current Therapy for Hypoplastic Left Heart Syndrome and Related Single Ventricle Lesions

Abstract

Universally fatal only four decades ago, the progress in the three-stage palliation of hypoplastic left heart syndrome and related single right ventricular lesions has drastically improved the outlook for these patients. While the stage II operation (hemi-Fontan or bidirectional Glenn) and stage III Fontan procedure have evolved into relatively low risk operations, the stage I Norwood procedure remains one of the highest risk and costliest common operations performed in congenital heart surgery. Yet, despite this fact, experienced centers now report hospital survivals in excess of 90% for the Norwood. This traditional three-stage surgical palliation has seen several innovations in the past decade aimed at improving outcomes, particularly for the Norwood procedure. One significant change is a renewed interest in the right ventricle-to-pulmonary artery shunt as the source of pulmonary blood flow, rather than the modified Blalock-Taussig shunt for the Norwood. The multi-institutional Single Ventricle Reconstruction trial randomized 555 patients to one or the other shunt, and these subjects continue to be followed closely as they now approach 10 years post-randomization. In addition to modifications to the Norwood procedure, the “hybrid procedure,” a combined catheter-based and surgical approach, avoids the Norwood procedure in the newborn period entirely. The initial hybrid procedure is then followed by a “comprehensive” stage II, that combines components of both the Norwood and the traditional stage II, and later completion of the Fontan. Proponents of this approach hope to not only improve short-term survival, but potentially longer-term outcomes, such as neurodevelopment, as well. Regardless of the approach, traditional surgical staged palliation or the hybrid procedure, survivals have vastly improved, and large numbers of these patients are surviving not only through their Fontan in early childhood, but into adolescence and young adulthood. As this population grows, it becomes increasingly important to understand the longer-term outcomes of these Fontan patients, not only in terms of survival, but also burden of disease, neurodevelopmental outcomes, psychosocial development and quality of life.

The Fontan Procedure for Single-Ventricle Physiology

“…Multicenter data have shown 1% to 2% hospital mortality after Fontan procedures. 1 In 2013, Stewart et al 21 reviewed the Society of Thoracic Surgeons Congenital Heart Surgery Database to evaluate outcomes according to the type of Fontan procedure (lateral tunnel or extracardiac). The extracardiac Fontan procedure was associated with significantly higher rates of Fontan failure and Fontan takedown as well as a longer hospital length of stay.…”

“…22 The survival rate for patients who have the Fontan operation today is 85% at 30 years. 1 Interestingly, only between 4% and 7% of patients receive a heart transplant within 20 years of the Fontan procedure. 1 Perhaps the multisystem burden of disease precludes transplant candidacy in patients with a Fontan procedure who present in the late stages of heart failure.…”

“…1 Interestingly, only between 4% and 7% of patients receive a heart transplant within 20 years of the Fontan procedure. 1 Perhaps the multisystem burden of disease precludes transplant candidacy in patients with a Fontan procedure who present in the late stages of heart failure. In a systematic review and meta-analysis, Doumouras and colleagues 23 compared transplant survival between patients with and without congenital heart disease.…”

“…Patients with systemic outflow tract obstruction and/or hypoplasia (eg, hypoplastic left heart syndrome) undergo a Norwood-type operation in the newborn period. The Norwood operation can be described in 4 parts: (1) reconstructing the aortic arch with the native proximal main pulmonary artery, usually supplemented with homograft tissue; (2) establishing pulmonary blood flow with a right ventricle to pulmonary artery Sano shunt or a systemic to pulmonary artery modified Blalock-Taussig shunt; (3) performing an atrial septectomy; and (4) ligating the patent ductus arteriosus.…”

Risk Factors for Death or Heart Transplant for Patients with Right Ventricular Dysfunction After the Norwood Procedure: A Secondary Analysis of the Single Ventricle Reconstruction Trial

“…Until the early 1980s, families were offered comfort care as the only therapeutic option. The first surgery for HLHS was attempted in 1961 but the first report of survivors was not until the 1970s (Ohye et al 2016;Noonan & Nadas 1958).…”