Transesophageal Echocardiography Was Useful in Determining the Treatment Plan for Moderate Aortic Stenosis-Like Findings Associated With High Left Ventricular Output Immediately Following Biological Valve Replacement: A Case Report

An elevated transvalvular pressure gradient and accelerated blood flow immediately following aortic valve replacement (AVR) is occasionally observed. It requires careful differentiation between structural factors, such as prosthetic valve dysfunction or patient-prosthetic mismatch (PPM), and non-structural factors, including high left ventricular output. A 73-year-old woman presenting with severe aortic regurgitation underwent AVR with a 25 mm stented bioprosthetic valve and coronary artery bypass grafting. After weaning from cardiopulmonary bypass (CPB) under catecholamine support, intraoperative transesophageal echocardiography (TEE) revealed findings corresponding to moderate aortic stenosis (AS), with a maximum blood flow velocity of 3.4 m/s and a mean pressure gradient of 23 mmHg. However, further TEE evaluation demonstrated a normal effective orifice area index (EOAI) of 1.24 cm²/m² and a short blood flow acceleration time (AT) of 42 ms. Consequently, prosthetic valve dysfunction and PPM were ruled out, and these findings were attributed to a hyperdynamic state with high left ventricular output. Reoperation was successfully avoided. A follow-up transthoracic echocardiogram (TTE) on postoperative day 4 confirmed normal valve mobility without any signs of stenosis, and the patient was discharged without complications. TEE played a crucial role in accurately identifying a high left ventricular output state masquerading as moderate prosthetic valve stenosis immediately following surgery, thereby preventing unnecessary surgical reintervention.