Systemic hyperkalemia and mild hypothermia for valve surgery in patients with patent internal mammary artery graft

Abstract

Myocardial protection is compromised in patients with a patent internal mammary artery (IMA) graft. We assessed the advantages of systemic hyperkalemia with mild hypothermia for valve surgery in patients with a patent IMA graft. Nine patients (mean age 71.5+/-7.0 years) with a patent IMA graft underwent valve surgery from May 2004 to July 2009. Of those, eight underwent aortic valve replacement and one mitral repair, with two double-valve surgery. Antegrade and retrograde blood cardioplegia were performed intermittently, and systemic potassium was given to all. The lowest bladder temperature was 27.2+/-2.4 degrees C, and the initial and peak systemic potassium levels were 6.8+/-1.4 and 8.0+/-1.6 mEq/l, respectively, while potassium at the end of the cardiopulmonary bypass procedure after sufficient modified ultrafiltration was reduced to 5.5+/-0.6 mEq/l. There was one hospital death due to ischemic colitis. Cardiac arrest was easily achieved in each patient without IMA or aortocoronary graft injury. The postoperative peak creatine kinase-MB level was 33+/-17 IU/l, with no ST changes seen in electrocardiogram findings or new asynergy seen in echocardiogram findings. Systemic hyperkalemia and mild hypothermia for valve surgery in patients with a patent IMA graft is a good option to reduce graft and myocardial injuries.