A carbon dioxide (CO2) embolism during endoscopic vein harvesting is a rare but potentially fatal complication. Early and accurate diagnosis is crucial for limiting the extent of the embolism and stabilizing the resulting cardiovascular compromise. We report a case of CO2 embolization during endoscopic vein harvesting. Transesophageal echocardiography was instrumental in the diagnosis and management of this patient by further improving the decision making process, which resulted in the best outcome. Mid-esophageal bicaval view is the best view to determine whether a CO2 embolism is coming from the upper or lower extremities.