Mitral valve surgery after previous CABG with functioning IMA grafts

Background. Mitral valve surgery after previous coronary artery bypass graf ting presents a challenging problem for the cardiac surgeon. An injury to p atent coronary artery bypass grafts, especially internal mammary artery gra fts, during reoperation via a redo sternotomy, may be fatal. Therefore, a r eliable alternative to the redo sternotomy is desirable to minimize potenti al injury to internal mammary artery grafts. Methods. Between February 1987 and October 1998, we performed 59 consecutiv e mitral valve operations after previous coronary artery bypass grafting su rgery (CABG). A total of 24 patients (41%) had functioning internal mammary artery (IMA) grafts and represent the population for this study. No patien ts were excluded for any reason. Of the 24 patients, 20 (83%) were men. Mea n 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 functio ning bilateral internal mammary artery grafts. All had 3 to 4+ mitral regur gitation (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 a n anterolateral right thoracotomy and 3 (12%) through a redo sternotomy. Tw enty-two (92%) patients, including the 3 patients in whom a redo sternotomy was used, had cannulation of the femoral artery and vein. Two patients req uired 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 aort ic 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%) th ere was myxomatous degeneration. Nine (34%) required valve replacement and 15 (66%) underwent repair. There were no operative or hospital deaths and a ll 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 wou nd 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.