A 2-year-old boy with a history of hypoplastic left heart syndrome (HLHS), status post Norwood-Sano procedure and bidirectional Glenn shunt (BDG), presents for Fontan operation. History is otherwise unremarkable.
Patients with single ventricle physiology, usually due to HLHS or tricuspid atresia, require staged surgical palliation, ultimately resulting in passive delivery of deoxygenated blood to the pulmonary circulation (bypassing the ventricle) and delivery of oxygenated blood to the systemic circulation via the single ventricle. In the neonatal period, a patent ductus arteriosus (PDA) provides systemic blood flow in patients with HLHS, so prostaglandin E1 is used in order to maintain the PDA patent and improve the pulmonary and systemic blood flows (Qp/Qs) until surgical palliation can be performed. The usual first-stage palliation for neonates with HLHS is the Norwood procedure, which entails the creation of a neo-aorta from the hypoplastic aorta and the main pulmonary artery (PA), thereby connecting the right ventricle (RV) to the systemic circulation. Pulmonary blood flow is maintained by the creation of either a modified Blalock-Taussig shunt (a Gore-Tex patch from the neo-aorta to the RPA) or, as in this case, a Sano modification (a Gore-Tex patch from the RV to the PA). The second-stage palliation for HLHS patients, the BDG, establishes blood flow from the SVC to the right and left PAs; this is done in order to decrease the exposure of the pulmonary circulation to the volume overload of a systemic arterial-to-PA shunt. The BDG is usually performed at around 6 months of age, when PVR has decreased, but it can be done as early as 2-3 months. The Fontan operation is the third and final stage of palliation for patients with HLHS, and generally is undertaken at between 2 and 4 years of age. In the Fontan procedure, the inferior vena cava (IVC) is connected to the PA, establishing a total cavopulmonary connection. The IVC-PA anastomosis can be accomplished either via an intra-atrial lateral tunnel or via an extracardiac conduit to the PA. A fenestration between the single atrium and the Fontan connections is frequently performed in order to decrease venous pressure and to allow for adequate ventricular volume loading.
Patients normally will have a transthoracic echocardiogram as well as a cardiac catheterization preoperatively to determine their readiness for completion of the Fontan operation. In addition to evaluation of the patient’s functional clinical status, preoperative evaluation should include a thorough assessment of these data, with emphasis on adequacy of valvular function, ventricular end-diastolic pressures, and transpulmonary pressure gradient. A careful neurologic history should be taken, as there is risk of systemic stroke due to venous emboli in patients who have undergone BDG. Parents should be informed that there is significant risk of venous throm-bosis and central nervous system complications after the Fontan ...