pediatrics
Hypoplastic Left Heart Syndrome
Treatment of Hypoplastic Left Heart Syndrome
Prostaglandin E1 (PGE1) infusion Staged surgical repair Sometimes heart transplantation Fortunately, most patients with hypoplastic left heart syndrome are now diagnosed with prenatal ultrasonography or fetal echocardiography, allowing initiation of prostaglandin E1 and other appropriate therapies immediately after birth and before organ hypoperfusion can occur. All infants with hypoplastic left heart syndrome should be stabilized immediately in a neonatal ICU or pediatric cardiac ICU. Vascular access should be established rapidly via an umbilical venous catheter and/or peripheral IV, whichever is quicker. Prostaglandin E1 (beginning at 0.05 to 0.1 mcg/kg/minute IV) is infused to prevent closure of the ductus arteriosus or to reopen a constricted ductus. Neonates, particularly those who are critically ill at presentation, usually require tracheal intubation and mechanical ventilation. Metabolic acidosis is corrected via infusion ofsodium bicarbonate. Severely ill neonates with cardiogenic shock may require inotropic drugs (eg,milrinone) and diuretics to improve cardiac function and control volume status. It is critical to keep pulmonary vascular resistance relatively high and systemic vascular resistance low to prevent marked pulmonary overcirculation at the expense of systemic perfusion. These resistance ranges are maintained by avoiding hyperoxia, alkalosis, and hypocarbia, all of which may lead to pulmonary vasodilation. Because oxygen is one of the most potent pulmonary vasodilators, infants are ventilated with room air or even hypoxic gas mixtures to aim for systemic saturations of 70 to 80%. If the infant requires mechanical ventilation, PCO2 can be controlled in the high normal or mildly elevated range. Systemic vascular resistance is managed by avoiding, or minimizing, the use of vasoconstricting drugs (eg,epinephrineor high-dosedopamine).Milrinonemay be beneficial because it can cause systemic vasodilation. In the uncommon circumstance of a markedly restrictive or prematurely closed patent foramen ovale, emergent transcatheter opening or enlargement of the foramen ovale may prevent imminent death. Keep pulmonary vascular resistance relatively high and systemic vascular resistance low to avoid increasing pulmonary circulation at the expense of systemic perfusion. Thus, avoid hyperoxia, alkalosis, and hypocarbia (which cause pulmonary vasodilation) and minimize use of vasoconstrictors. Survival ultimately requires staged surgical procedures that enable the right ventricle to function as the systemic ventricle and establishing a controlled source of pulmonary blood flow. Stage 1, done during the first week of life, is the Norwood procedure. The main pulmonary artery is divided, the distal stump is closed with a patch, and the hypoplastic aorta and proximal pulmonary artery are combined into a neoaorta. The ductus arteriosus is ligated. Pulmonary blood flow is reestablished by inserting a right-sided modified Blalock-Taussig-Thomas shunt or a right ventricular-pulmonary artery conduit (Sano modification). Finally, the atrial septal communication is enlarged. An alternative, hybrid procedure, often a joint effort of heart surgeons and interventional cardiologists, involves inserting a stent into the ductus arteriosus (to maintain systemic blood flow) and placing bilateral branch pulmonary artery bands (to limit pulmonary blood flow). In some centers, the hybrid procedure is reserved for higher risk patients (eg, preterm or low birth weight infants, those with multisystem organ dysfunction). Stage 2, done at 3 to 6 months of age, consists of a bidirectional Glenn or a hemi-Fontan procedure. These procedures connect the superior vena cava to the right pulmonary artery, which allows about half of the systemic venous return to bypass the right atrium and flow directly to the lungs for oxygenation. Unlike the bidirectional Glenn, the hemi-Fontan does not completely detach the superior vena cava from the right atrium. The 3rd stage, done at 18 to 36 months, is a modified Fontan procedure, the inferior vena cava flow is diverted to the confluence of the superior vena cava and pulmonary artery. Diversion can be done via a baffle within the right atrium or by an extracardiac tube graft. The mortality risk for children with hypoplastic left heart syndrome is highest in the first year of life ( Treatment reference ). About 90% of patients who survive infancy will survive up to age 18. As with other children with complex congenital heart disease, survivors may have some degree of neurodevelopmental disability, which may be due to preexisting developmental abnormalities of the central nervous system (CNS) or to overt or occult CNS hypoperfusion or thromboemboli occurring during the multistage procedures. Heart Transplantation None Prevention None 1.Siffel C, Riehle-Colarusso T, Oster ME, et al: Survival of children with hypoplastic left heart syndrome.Pediatrics136(4): e864–e870, 2015. 