The patient was a 75-year-old female with a history of hypertension and atrial fibrillation. She experienced severe lower abdominal pain and presented to our hospital. The patient was diagnosed as having strangulated ileus by abdominal CT scan and underwent emergency surgery. She was in shock unresponsive to catecholamine the day after the surgery in ICU. Since transthoracic echocardiography (TTE) revealed right ventricular dilatation and left ventricular constriction, pulmonary thromboembolism was suspected. The patient was then placed on extracorporeal membrane oxygenation, following which the hemodynamics improved. Although there were no signs of pulmonary thromboembolism on enhanced CT, TTE performed after hemodynamics stabilization revealed severe aortic stenosis as the cause of low cardiac output. She was discharged 22 days after the surgery. When the patient was not evaluated adequately in emergency, it is necessary to assess repeatedly depending on the alteration of patient status and choose an appropriate treatment.