Occult ventricular fibrillation during on-pump beating coronary artery bypass grafting: A case report

Ventricular fibrillation (VF) can occur during on-pump beating coronary artery bypass grafting (CABG) and may remain unrecognized during cardiopulmonary bypass (CPB) despite preserved systemic perfusion. We report a 74-year-old man undergoing on-pump beating CABG in whom VF developed during extreme cardiac displacement for obtuse marginal anastomosis. Direct operative visualization was limited, transesophageal echocardiography became intermittent, and the electrocardiogram (ECG) showed low-voltage, noise-contaminated signals, delaying recognition for approximately 15 min. After detection, defibrillation was unsuccessful, and cardioplegia was administered. The patient was weaned from CPB without difficulty, required only low-dose norepinephrine, and recovered without neurological sequelae. Postoperative echocardiography demonstrated preserved systolic function. This case highlights a monitoring pitfall: VF may remain “occult” during CPB when both ECG and echocardiographic signals are compromised by stabilizer use and cardiac displacement. Attention to ECG signal quality and structured cross-checking with adjunct monitoring cues may facilitate earlier recognition and timely intervention.