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. (C) 1999 by The Society of Thoracic Surgeons.