B50-20 The Fontan Under Pressure: Decompensation Triggered by Sepsis and Mechanical Ventilation

Abstract Introduction Patients with Ebstein anomaly who have undergone Fontan palliation represent a uniquely challenging patient population due to the complex, single-ventricle physiology and passive pulmonary circulation. Maintaining low pulmonary vascular resistance and optimal preload is essential to preserve adequate hemodynamics and oxygenation. However, acute illness such as sepsis and use of mechanical ventilation place these patients at risk for rapid compromise of the Fontan circulation. Description A 24-year-old female patient with a history of Ebstein anomaly status post Glenn shunt, tricuspid valve patch closure, atrial septectomy, and fenestrated Fontan procedure with extracardiac pericardial baffle presented with necrotizing soft tissue infection of the right thigh. She underwent emergent debridement on hospital day 1. On day 3, during planned repeat debridement, she developed hypoxemia on induction. Bronchoscopy was performed without evidence of abnormal secretions or mucus plugging. Her postoperative course was complicated by persistent hypoxemia. Despite maximal ventilator support at a fraction of inspired oxygen of 1.00 and positive end-expiratory pressure (PEEP) of 10, oxygen saturation remained in the mid-to-high 80s. Pulmonology and cardiology recommended inhaled nitric oxide, epoprostonol, aggressive diuresis, and PEEP of 0 to minimize right heart afterload. A transthoracic echocardiogram revealed an ejection fraction of 40-45% with a positive saline contrast study indicating the presence of a large right-to-left shunt. After stabilization and extubation, the patient was discharged on sildenafil and oral diuretics. During outpatient follow-up, transesophageal echocardiogram demonstrated a patent Fontan baffle without fenestration and confirmed positive saline contrast predominantly to the right upper pulmonary vein. No pulmonary arteriovenous malformation (AVM) was seen on CT angiography; however, extensive venous collaterals arising from the superior and inferior mediastinum extending to the bilateral hilar pulmonary veins were noted. Left and right heart catheterization demonstrated multiple venovenous collaterals status post coil embolization of 3 large collateral networks. Her systemic saturation improved from 87% to 98%. A less prominent agitated saline appearance was noted on the follow-up echocardiogram. Discussion This case illustrates the hemodynamic vulnerability of Fontan patients and the complex interplay between sepsis, mechanical ventilation, and Fontan single ventricle physiology. Positive pressure ventilation can paradoxically result in hypoxemia by impeding venous return and increasing pulmonary vascular resistance. The occurrence of hypoxemia in this population necessitates evaluation for multiple shunt etiologies, including patent Fontan fenestration, pulmonary AVMs, or venovenous collaterals, as management strategies vary. Therefore, consultation with pulmonology and cardiology and use of pulmonary vasodilators with low-PEEP strategies can be lifesaving. This abstract is funded by: None