Spontaneous Echo Contrast Mistaken for Left Ventricular Thrombus during Venoarterial Extracorporeal Membrane Oxygenation

Spontaneous echo contrast (SEC) is often observed in patients with mitral stenosis, atrial fibrillation, cardiomyopathy, or a ventricular aneurysm [1]. SEC is a smoke-like echo density observed on echocardiograms, and is caused by increased red blood cell aggregation during low-flow states. It is also a risk factor of thromboembolism [2]. SEC can be observed in patients with severe ventricular dysfunction receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO). We present a case in which left ventricular-SEC (LV-SEC) was mistaken for a LV thrombus during VA-ECMO for severe LV dysfunction. A 36-year-old female patient diagnosed with acute fulminant myocarditis was provided VA-ECMO support on hospital day (HD) 1. Briefly, VA-ECMO (RotaFlow; Maquet Inc., Hirrlingen, Germany) was implanted in the right femoral artery (15-French arterial cannula) and the left femoral vein (20-French venous cannula). Her height and body weight are 163 cm and 52 kg (body surface area, 1.53 m). VAECMO was initiated with a circuit flow of 3.5 L/min (cardiac index, 2.3 2L/min/m). Her creatine kinase-myocardial band and troponin-I levels at admission were 188.03 ng/ml (normal range, 0 to 5 ng/ml) and >50.0 ng/ml (normal range, 0 to 0.78 ng/ml), respectively. Impaired ventricular function (ejection fraction, 22%) suspected as acute fulminant myocarditis was detected by transthoracic echocardiography (TTE) at admission. TTE revealed decreased LV function (ejection fraction, 10%) with mild mitral regurgitation (grade II) immediately after VA-ECMO. Opening of the aortic valve and arterial pulsatility were not observed. Pulmonary edema was aggravated on HD 4. Left atrial (LA) decompression was achieved using a LA catheter (20-French femoral venous cannula) by balloon atrial septostomy through the right femoral