Continuous retrograde cardioplegia simplifies aortic valve replacement in the presence of a patent internal mammary artery

Abstract

We read with great attention and interest two reports [1, 2] in The Annals describing surgical techniques for aortic valve replacement in patients with previous coronary artery bypass grafting and a functioning internal mammary artery (IMA) graft. Both articles emphasize the benefits of avoiding dissection and manipulation of the IMA but differ on the method of myocardial protection, a problematic issue because of continuous perfusion of the heart by the unclamped IMA. Myocardial protection in the series of Byrne and associates [1] was achieved mainly by antegrade with or without retrograde perfusion of crystalloid cardioplegia at 4°C, supplemented with moderate to deep systemic hypothermia (median temperature, 20°C). Savitt and colleagues [2], on the other hand, have advocated the use of continuous antegrade oxygenated blood perfusion and mild systemic hypothermia of 32°C.