Mitral valve surgery after previous CABG with functioning IMA grafts.

BACKGROUND: Mitral valve surgery after previous coronary artery bypass grafting presents a challenging problem for the cardiac surgeon. An injury to patent coronary artery bypass grafts, especially internal mammary artery grafts, during reoperation via a redo sternotomy, may be fatal. Therefore, a reliable alternative to the redo sternotomy is desirable to minimize potential injury to internal mammary artery grafts.

METHODS: Between February 1987 and October 1998, we performed 59 consecutive mitral valve operations after previous coronary artery bypass grafting surgery (CABG). A total of 24 patients (41%) had functioning internal mammary artery (IMA) grafts and represent the population for this study. No patients were excluded for any reason. Of the 24 patients, 20 (83%) were men. Mean age was 66+/-13 years (range 41 to 83 years) and the mean duration from CABG was 5.3+/-3.6 years (range 0.1 to 12 years). Four (17%) had functioning bilateral internal mammary artery grafts. All had 3 to 4+ mitral regurgitation (MR) at the time of mitral valve surgery and the mean preoperative ejection fraction (EF) was 40%+/-14% (range 20% to 74 %).

RESULTS: Twenty-one (88%) patients underwent mitral valve surgery through an anterolateral right thoracotomy and 3 (12%) through a redo sternotomy. Twenty-two (92%) patients, including the 3 patients in whom a redo sternotomy was used, had cannulation of the femoral artery and vein. Two patients required axillary artery cannulation. All 21 patients in whom the mitral valve was approached through a right thoracotomy underwent deep hypothermia (19.6 degrees+/-2.1 degrees C, range 14 degrees to 25 degrees C) without aortic clamping, with a mean duration of CPB of 138+/-46 minutes (range 65 to 249 minutes). In 18 (75%), the MR was ischemic in origin and in 6 (25%) there was myxomatous degeneration. Nine (34%) required valve replacement and 15 (66%) underwent repair. There were no operative or hospital deaths and all patients were discharged to home or to a rehabilitation facility. There were 4 (17%) major complications. Two patients suffered respiratory failure requiring tracheotomy, 1 patient developed a perioperative MI requiring an intraaortic balloon pump and 1 developed heart block requiring a permanent pacemaker. There were no neurologic, peripheral vascular, bleeding, or wound complications.

CONCLUSIONS: Reoperative mitral valve surgery in the setting of functioning IMA grafts, even in the face of depressed LV function, can be done safely and with minimal morbidity.