P029: "TIME IS MYOCARDIUM" TEE DIAGNOSIS OF CIRCUMFLEX CORONARY ARTERY OCCLUSION DURING MITRAL VALVE REPAIR
Robert B Lofgren, DO; University of Florida
Introduction: Circumflex artery injury during mitral valve (MV) replacement is a potentially devastating complication leading to significant postoperative morbidity if not diagnosed early. It is a rare complication of the surgery, only occurring in 1.8% of patients . Injury can occur by thrombus, hematoma formation from surgical trauma, or as in this case, from suture misplacement. Most existing case reports center around detection of the occlusion postoperatively with cardiac catheterization, but our case highlights the advantage of intraoperative transthoracic echocardiography (TEE) to expediently diagnose circumflex artery occlusion and allow for prompt revascularization.
Case: A 52 yo male with history of severe MV regurgitation caused by previous infective endocarditis underwent repair with mitral annuloplasty ring. Preoperative heart catheterization was remarkable for normal coronary arteries and right dominance. Preoperative TEE was remarkable for severe mitral regurgitation but normal ejection fraction (EF) of 60-65%. Intraoperative TEE after revealed lower EF of 40% (compared to preoperative TEE), severe anteriorly directed MR, P2 prolapse, flail chordae, as well as reversal of flow in the left superior pulmonary vein consistent with severe mitral regurgitation. Repair of the valve consisted of quadrangular resection of P2, P1 and P3 leaflet height reduction, closure of P1 leaflet cleft, and placement of 36 mm Edwards Physic II mitral annuloplasty ring. During separation from cardiopulmonary bypass, ST segment elevations were observed in leads II, III, AVF. TEE revealed severe hypokinesis in the inferior/inferolateral walls and depressed EF (10%) which persisted despite reperfusion. Furthermore, Color Doppler assessment of the circumflex artery showed a lack of flow past a point in the vessel (flow was observed on initial TEE). Findings were discussed with the surgery team and a diagnosis of circumflex coronary artery compromise secondary to annuloplasty sutures was made. Subsequently, a saphenous vein coronary artery bypass graft (CABG) to the large M1 distal to the obstruction was successfully completed. Following CABG, repeat TEE revealed improved ventricular function and stable mitral valve repair. The patient was weaned off cardiopulmonary bypass. Postoperatively, the patient had continued improvement in his cardiac function and was later discharged from the hospital in stable cardiac condition.
Discussion: Circumflex artery injury is a known complication, but uncommon occurrence during mitral valve repair. If not recognized early, it can result in myocardial infarction leading to severe postoperative morbidity. The circumflex artery is particularly susceptible to distortion by annular sutures because anatomically it courses within the atrioventricular groove in close proximity to the mitral annulus. In an anatomical study, Pessa and colleagues showed a short distance between mitral annulus and coronary arteries in right dominant hearts of 3.9 + 1.8 mm . Echocardiographic measurements by Ender et al. revealed a distance of 1.3 mm for right dominance and 2.2 mm for left dominance type . Awareness must be maintained about circumflex artery occlusion during MV repair given how potentially lethal this complication is. This case highlights the utility off intraoperative TEE to diagnose new wall motion abnormality quickly and avoid disastrous complications.