Single ventricle disease is a rare disorder occurring approximately 4-8 per 10,000 births and in 7.7% of congenital heart disease diagnosed at childhood (1). Patients with single ventricle disease undergo three surgical procedures for palliation that culminates in the Fontan Procedure, which produces the anatomy shown at right. The cavopulmonary connection allows flow from the vena cava to the pulmonary arteries while the single ventricle pumps blood to the aorta. The effects of pregnancy on Fontan physiology are discussed here.
This case involves a 28 year-old G2P0010 who presented for induction of labor at 36 weeks and 0 days. Her pregnancy was planned in concert with her cardiologists. Her medical history consists of cyanotic congenital heart disease including single ventricle of right ventricular morphology and transposition of the great vessels with severe valvular and subvalvular pulmonic stenosis. Her surgical history includes modified Blalock Taussig shunt, bilateral bidirectional Glenn, modified lateral tunnel Fontan with subsequent revision of the atrial septal defect, and ligation (coiling) of superior vena cava to left atrium vessels. Four years prior to this admission, she developed IART after a spontaneous abortion. Pre-pregnancy she underwent ablation of 2 of 3 IART circuits; the 3rd circuit was inaccessible due the presence of her atrial baffle. Early in her pregnancy she received a single chamber intraatrial pacer for antitachycardia pacing due to refractory IART and symptomatic atrial flutter. Throughout pregnancy, anticoagulation with enoxaparin subcutaneously was used as well as escalating doses of amiodarone and metoprolol due to recurrence of her atrial dysrhythmias. The plan for her delivery was IOL, early epidural placement, and assisted second stage of labor. Focus was placed on preventing adrenergic activation throughout labor due to recent dysrythmias. A portable vitals monitor was used in her L&D room to provide continuous EKG and right radial arterial pressure monitoring. Via her epidural catheter, she received lidocaine 1.5% with epinephrine 1:200,000 in divided doses immediately after catheter placement, and an infusion of bupivacaine 0.1% was started. She later received lidocaine 2% before transport to the OR for vaginal delivery. The patient had a successful vacuum assisted vaginal delivery and maintained stable hemodynamics and normal sinus rhythm throughout delivery and her postpartum hospital stay.
Management of patients with Fontan physiology includes balancing preload, afterload, pulmonary vascular resistance, and cardiac output. The physiological changes of pregnancy include an increase in preload, decrease in afterload, increase in heart rate, and an increase in blood volume (2). Whether a patient with Fontan physiology can handle these changes depends on whether the pulmonary vasculature and the single ventricle can handle the increased preload. Cardiac output is determined most importantly by preload in a patient with Fontan physiology. Additionally, pulmonary vascular resistance determines blood flow to the single ventricle. Therefore, factors affecting PVR such as PaO2, PaCO2, and pH also influence anesthetic management. Neuraxial anesthesia must be managed carefully due to decreases in preload. A review article from 2015 concluded that labor epidural is the most common management and an appropriate choice as long as low-concentration local anesthetics are used and incremental dosing is chosen to minimize abrupt decreases in preload. An arterial catheter is also helpful for these patients in monitoring immediate changes in blood pressure with epidural anesthesia (2). For this patient, monitoring for dysrhythmias was also important, and management included continuation of antiarrythmic medications, continuous EKG and arterial blood pressure monitoring, and having emergency drugs immediately available.
1. O’Leary P. Prevalence, clinical presentation and natural history of patients with single ventricle. Progress in Pediatric Cardiology. 2002; 1: 31-38.
2. Tiouririne M. et al. Anesthetic Management of Parturients with a Fontan Circulation: A Review of Published Case Reports. 2015; 19: 203-209.