Ann Thorac Surg 2002;73:1439-1440
© 2002 The Society of Thoracic Surgeons
Invited commentary
Ruggero De Paulis, MDa
a Cattedra di Cardiochirurgia, Università di Roma, Tor Vergata, European Hospital, via Portuense 700, 00149 Rome, Italy
e-mail: depauli{at}tin.it
There is probably no field that has stimulated so many studies aimed at identifying the best operative strategy or the optimal composition of cardioplegia than intraoperative myocardial protection. Although cardioplegic techniques for coronary artery bypass grafting are widely used around the world, a minority of surgeons still prefer the simplicity of noncardioplegic techniques such as intermittent aortic cross-clamping. Strengthened by new knowledge and insights into the mechanisms of ischemic preconditioning, authors of many recent studies compared the intermittent cross-clamping technique with the use of various cardioplegic solutions. In most studies, there were no substantial differences in mortality and morbidity between the two methods. However, given the low operative mortality for routine coronary artery bypass grafting, a truly randomized trial comparing differ-ent techniques would require such a large number of patients that it would be impractical.
In their excellent, provocative study, Raco and colleagues showed that in the hands of a single experienced surgeon, the intermittent cross-clamp technique is a safe and effective method. The low average duration of ischemia appears to be the most important factor for their outstanding clinical results. Many reports on intermittent aortic cross-clamping present the results of a single surgeon or a few experienced surgeons, which underlines the importance of brief ischemia times.
Although excellent results can be achieved with the intermittent cross clamp technique, recommending this technique for large-scale application or transferring these results to other cardiac centres is another matter. Intermittent cross-clamping is not preferred by trainees because longer periods of ischemia could contribute to unfavorable outcomes. Furthermore, there is no sound evidence that this technique can be applied safely to all coronary artery bypass grafting procedures. In this respect, there is no doubt that the severely atherosclerotic aorta should be approached with a no-touch technique that avoids aortic cannulation. In addition, in patients with unrecognized atherosclerotic disease of the ascending aorta, a single cross-clamp can be devastating, and multiple cross-clamping cannot be any better.
Finally, in this context it seems appropriate to mention the technique of intermittent antegrade warm blood cardioplegia that is rapidly being adopted worldwide because of its simplicity, low cost, and efficacy. To some extent, it is a simpler form of ischemia and reperfusion and is in some ways similar to the intermittent cross-clamp technique. After placement of a single cross-clamp, the heart is intermittently perfused with the patient’s whole blood enriched with potassium only. Because the heart has no electrical or mechanical activity, accumulation of oxygen debt is much slower than with the intermittent cross-clamp technique, therefore, the ischemia period can be more safely prolonged. During the period of warm reperfusion, oxygen debt is repaid, cardiac metabolism is restored, and new episodes of ischemia can be tolerated safely.
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Isolated myocardial revascularization with intermittent aortic cross-clamping: experience with 800 cases
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Ann. Thorac. Surg. 2002 73: 1436-1439.
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