ST Elevation During Open Heart Surgery
Floating Air Bubble in Saphenous Vein Graft
A 58-year-old man with severe mitral regurgitation and silent myocardial ischemia underwent mitral valvuloplasty and CABG. Preoperative coronary angiography revealed a total occlusion of the left circumflex coronary artery. The right coronary artery supplied the collateral flow to the posterior descending branch of the left circumflex coronary artery. The saphenous vein graft (SVG) was anastomosed to this branch after valvuloplasty. Just before closure of the chest wall, the ECG showed severe ST-segment elevation in leads II, III, and aVF (Figure 1A). Despite continuous infusion of nitroglycerin and initiation of nicorandil, ST-segment elevation did not recover; therefore, an intra-aortic balloon was inserted. As soon as the operation was finished, the patient was taken to the catheterization laboratory, and emergency coronary catheterization was performed. His native coronary arteries showed no changes compared with preoperative findings. Interestingly, a floating air bubble was demonstrated in the distal part of the anastomosed SVG (Figures 2A, 2B, and 2C). As the bubble traveled to the distal part of the SVG, the ST segment was further elevated (Figure 1B). A 6F AL-1 guiding catheter for coronary angioplasty was then positioned at the ostium of the SVG, and a 0.014-inch guidewire was advanced into the posterior descending branch through the SVG. The tip of the thrombectomy catheter (Thrombuster; Kaneka Medix Corp) was placed at the distal SVG (Figure 2D) and pulled back, aspirating blood and the bubble. Immediately after this maneuver, brisk blood flow was restored (Figure 2E), with restoration of ST-segment elevation (Figure 1C).
Coronary air embolism is a potential complication of cardiopulmonary bypass surgery, especially open heart surgery. Nevertheless, it is unusual for emergency coronary catheterization to demonstrate a floating air bubble in the coronary artery. Air embolism can be fatal if not treated promptly. Distal air aspiration with a thrombectomy catheter is a quick and effective maneuver for rescuing the distal circulation in cases of air embolism associated with cardiac surgery or catheterization.