Hypoplastic Left Heart Syndrome and the Parturient
Abstract Number: 221
Abstract Type: Case Report/Case Series
Hypoplastic left heart syndrome (HLHS) is a congenital anomaly afflicting 0.025% of all live births. The syndrome is characterized by abnormal development of the left-sided cardiac structures resulting in left ventricular (LV) hypoplasia. Although the unifying feature is LV hypoplasia, the presence of other cardiac anomalies, including aortic atresia, mitral atresia, and/or ventricular septal defect, is not uncommon. Neonates with HLHS have an arterial duct-dependent systemic circulation. As the ductus arteriosus (DA) closes, systemic perfusion decreases and hypoxemia, acidosis, and shock develop. System perfusion can be temporarily preserved by maintaining patency of the DA via a prostaglandin infusion. Ultimately, the patient must undergo surgery for long-term survival.
In 1971, the Fontan procedure became the definitive palliative operation for a number of cardiac malformations, including pulmonary atresia (PA), tricuspid atresia (TA), and HLHS. The Fontan establishes a passive pulmonary circulation by routing venous blood away from the right atrium to the pulmonary arteries without passing through the heart. The right ventricle (RV), in HLHS, and the LV, in PA and TA, maintains systemic circulation but is completely preload-dependent on the passive pulmonary circulation. Pulmonary blood flow, and thus cardiac output, is dependent on the central venous pressure providing a driving pressure that overcomes the pulmonary vascular resistance. The introduction of the Fontan has increased the number of women reaching childbearing age.
Over the past decade, there have been a few case reports describing a parturient with a Fontan and a systemic LV. Until now, discussion of the parturient with a Fontan and a systemic RV has been absent from the literature. The physiologic changes of pregnancy superimposed on the Fontan circulation and a systemic RV provide an interesting set of challenges. Specifically, the uterus may compromise venous return which is integral to pulmonary blood flow with Fontan physiology. Catecholamine surges from labor pain can lead to hemodynamic changes which may be poorly tolerated by the RV. Finally, the univentricular heart may be unable to compensate for the increase in blood volume and cardiac output accompanying pregnancy and delivery.
Over the past year, we have had the opportunity to care for two parturients with HLHS. Both women underwent a series of staged procedures including the Norwood, the bi-directional Glenn, and finally, the Fontan. Our first patient was a 20 year-old G3P0020 who presented at 33 weeks with breech presentation and active labor. She was delivered emergently via cesarean section with regional anesthesia. Our second patient was a 22 year-old G2P0010 at 36 weeks who presented in labor. She subsequently had a spontaneous vaginal delivery with epidural analgesia. The presentation will focus on the anesthetic implications and management of a parturient with both a Fontan and a systemic RV.