More children with complex congenital heart diseases survive thanks to the single ventricle pathway. It is a multistage surgical palliation designed to offload the single dominant ventricle from volume overload by gradually shunting the systemic venous blood directly to the pulmonary circulation. At IJN, 30-50 children complete this pathway yearly.
It starts with pulmonary blood flow optimization during early infancy (a modified Blalock-Taussig shunt or PDA stenting if there is pulmonary underflow or a pulmonary artery banding if there is pulmonary overflow), followed by the Glenn procedure (redirection of SVC flow to the pulmonary arteries) in late infancy, and the Fontan procedure (redirection of IVC flow to the pulmonary arteries) in early childhood. The main pulmonary artery will be transected as well, either during the Glenn or Fontan operation, leaving the single ventricle to pump blood only to the systemic circulation.
The single ventricle pathway is not corrective. A child with a single ventricle will have a cardiac output that is limited by the passively-flowing pulmonary blood flow (as there is no subpulmonic ventricle pumping blood to the lungs). They cannot tolerate strenuous physical activity as the cardiac output cannot be readily increased.
They will also remain mildly cyanosed as most Fontan circuits have a fenestration between the inferior conduit and the atrium to help increase the limited cardiac output in case of an increased pulmonary blood pressure e.g. residual vessel stenosis, pleural effusion, or pneumonia.
Despite the reduced cardiac output, patients are able to perform physical activities of moderate intensity. The Fontan palliation offers patients a chance to go to school, travel, get a job and contribute to the society, have a family and lead a near-normal life. When the surgical scar is concealed, these patients are well, only to reveal their deficiencies when exercising vigorously.
On average, patients with single ventricle have an average lifespan of 40-50 years. However, heart failure tends to set in earlier before death. Complications include worsening cyanosis (due to collateral circulation formation); cirrhotic liver, liver failure, and increased risk of liver carcinoma (due to chronic liver congestion); protein-losing enteropathy, plastic bronchitis, and pleural/pericardial effusion (due to congestion of the lymphatic drainage); and the tendency for blood clot formation/pulmonary embolism (due to loss of thrombolytic factors and sluggish flow of blood in the Fontan circuit) are common endpoints experienced by these patients.
Although the thought of multiple surgeries and the risk of eventual Fontan failure are daunting, single ventricular palliation has successfully changed the lives of many children with complex congenital heart disease who would otherwise be denied a chance to live.