الفهرس 
Anatomy of the Coronary VesselsOnly 14 pages are availabe for public view
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Abstract
Since the introduction of normothermic blood cardioplegia in 1991, many studies have shown its superior effects on myocardial protection compared with those of conventional cold blood cardioplegia. To meet an increased myocardial energy demand and avoid warm ischemic injury during normothermic cardioplegia, continuous and homogeneous delivery of cardioplegic solution has been suggested to be preferable. During coronary artery bypass procedures, however, continuous infusion of cardioplegic solution must be interrupted to permit adequate visualization during the distal anastomosis. Moreover, the presence of critical coronary stenoses limits the delivery of cardioplegic solution to ischemic regions of the heart, particularly when revascularization with the internal mammary artery prevents vein graft infusions to the left anterior descending coronary artery. Interruptions or inadequate distribution of normothermic cardioplegia may induce anaerobic metabolism and warm ischemic injury. To avoid this problem, tepid (32°C) blood cardioplegia was recently introduced. The technique has been reported to reduce anaerobic myocardial lactate and acid release without inhibiting myocardial metabolic activity. Decreasing the heart temperature from 37° to 32°C may provide a buffer to ischemic injury when cardioplegia delivery is interrupted or nonhomogeneous. In recent reports, minimally diluted oxygenated blood with concentrated arresting agents as the cardioplegic vehicle was proposed as an alternative technique to the standard 4:1 dilution of blood to crystalloid solution. The technique was reported to increase oxygen carrying capacity during cardioplegia. Although the technique has been reported to provide superior clinical results, the published data on its effects on myocardial metabolism and cardiac function are limited.
Eighty patients were enrolled in the present clinical study to compare the effect of diluted cold blood cardioplegia with tepid blood cardioplegia on myocardial and vascular protection as well as the surgical outcome of the coronary artery bypass grafting operations.
The data showed that the group of patients who experienced tepid cardioplegia had significantly lower systemic vascular resistance and lower cardiac enzymes levels compared to those who experienced cold blood cardioplegia. On the other hand, the tepid blood cardioplegia group had significantly higher central venous pressure and cardiac index values compared to those who experienced cold blood cardioplegia.
Finally, we concluded that tepid blood cardioplegia is a safe and efficient method of myocardial protection and demonstrates advantages when compared with cold blood cardioplegia in coronary artery bypass grafting operations.