A Stab in the Heart: Scimitar Pulmonary Venous Anomaly Complicating a Case of Cardiogenic Shock

Abstract

Introduction Scimitar syndrome is described as an abnormal connection between one pulmonary vein and the right atrium or vena cava. Case presentation 40 year old female presented with respiratory failure and septic shock that was unresponsive to pressors and IV fluids. Transthoracic echocardiogram showed severely dilated right ventricle with severe tricuspid regurgitation. Chest computed tomography angiogram (CTA) was negative for pulmonary embolism but showed right upper pulmonary vein connecting to inferior vena cava consistent with Scimitar anomaly. (Figure 1) Invasive hemodynamic evaluation showed mixed venous saturation (SvO2) 14%, cardiac index (CI) 1.89 L/min/m2, systemic vascular resistance (SVR) 754 dynes, severely elevated filling pressures, and pulmonary artery pressure (PAP) 77/44 (57) mmHg. Dialysis, dobutamine and inhaled nitroglycerin (iNO) were added to pressors for RV support. Follow up hemodynamic profile showed SvO2 75%, CI 4.9 L/min/m2, improved filling pressures, SVR 473 dynes, PAP 79/37 (48) mmHg. However, liver/kidney function and lactic acid continued to worsen indicating inadequate organ perfusion. Inaccurate SvO2 and subsequent CI and SVR calculation in the setting of L to R shunt through the anomalous vein was suspected. Subsequently, the decision was made to titrate hemodynamic support using MAP>70 accepting the presence of shunt, after which lactic acid and liver/kidney function started improving. Unfortunately, the patient suffered hypoxemic cardiac arrest. The rate of iNO was decreased as it was thought to increase V/Q mismatch despite its hemodynamic benefit to RV. Initiation of extracorporeal membrane oxygenation was difficult because of severe vasospasm. Vegetative state was noted and care was withdrawn per family request. Discussion The patient's hemodynamic profile was consistent with cardiogenic shock secondary to acute RV failure caused by initial IV fluid administration. RV support in the setting of pulmonary hypertension was achieved with dialysis, dobutamine and iNO. Improving hemodynamic parameters obtained by pulmonary catheter didn't correlate with worsening laboratory perfusion parameters. The availability of chest CTA showing an unexpected pulmonary venous anomaly helped our multidisciplinary team explain the inaccuracy of hemodynamic parameters.