Norwood Procedure for Hypoplastic Left Heart Syndrome

Transcript of video: Hypoplastic Left Heart Syndrome is a very severe form of congenital heart disease, in which, the left ventricle, aorta and mitral and aortic valves are hypoplastic and valves may be atretic as well. It has a very poor survival. Norwood procedure is the first stage palliation for hypoplastic left heart syndrome, and a second stage palliaton, bidirectional Glenn procedure is done, to separate the pulmonary and systemic circulations, and finally, a Fontan procedure, Fontan type of procedure, connecting inferior vena cava also to the pulmonary circulation, is done at a still later, as a third stage.

This is diagrammatic representation of hypoplastic left heart syndrome. Left ventricular cavity is hypoplastic, mitral valve is either very small or atretic, same is true of aortic valve, and ascending aorta is hypoplastic. This has a very poor survival and factors which help postnatal survival are the presence of a patent ductus arteriosus, and an atrial septal defect. After birth, PDA can be maintained by using prostaglandin infusion, to get time for surgical procedures.

This is diagrammatic representation of Norwood procedure. As the aorta is small in hypoplastic left heart syndrome, proximal portion of the pulmonary artery is taken and along with the valve, it is used to reconstruct the proximal aorta, this region, and it is connected to the right ventricle. Left ventricle is not useful as a systemic pump because it is hypoplastic. So the right ventricle is used as a systemic pump, and the neoaorta constructed from the pulmonary artery, is used to connect the right ventricle to systemic circulation. An atrial septal defect is required, to get blood from the left atrium. Then, as pulmonary artery is transsected, pulmonary circulation is maintained by producing a graft, from the subclavian artery to the pulmonary artery. A Gore-Tex tube is used and this maintains, this is a Blalock-Taussig shunt, which maintains pulmonary circulation. So right ventricle maintains both systemic and pulmonary circulation after a Norwood procedure. Once the pulmonary vascular resistance falls, this Blalock-Taussig shunt is taken down, as the second stage procedure, and then superior vena cava is anastomosed to the pulmonary artery, in a bidirectional Glenn procedure. At that time, pulmonary and systemic circulations are fully separated. Right ventricle will pump to the aorta, and systemic venous pressure is used to drive the pulmonary circulation after the bidirectional Glenn procedure, which is done at about 6 months. The initial Norwood procedure is done at about few days after birth. And finally, there is a third stage palliation. Inferior vena caval flow is also directed to the pulmonary arteries using a Fontan modification, so that, finally, two circulations are totally separate.