Role of physiological state 'normothermia' in internal thoracic artery spasm after harvesting

Vasospasm is often faced after the operative preparation of internal thoracic artery. Different vasodilating pharmacological agents are being used to eliminate this problem. During the preparation of internal thoracic artery, normal, local, and systemic temperatures are lost. We aimed to find out the effect of this decrease in temperature on the free flow of internal thoracic artery.

We investigated the effects of normal saline solution at 20 degrees C (group I), papaverine at 20 degrees C (group II) and normal saline solution at 37 degrees C (group III). Each group contained 20 patients undergoing coronary bypass. Free flow of the left internal thoracic artery was measured after mobilization. After approximately 18 min the graft had been sprayed with one of the agents, and the second free flow was measured (t-interval was 18.2+/-2.1 for group I, 18.3+/-1.8 for group II, and 17.5+/-1.9 for group III).

Normal saline solution at 20 degrees C did not cause a significant change. Topical papaverine at 20 degrees C increased the flow from 42.1+/-10.7 ml/min to 77.5+/-17.9 ml/min (p < 0.0001). A significant increase also occurred with normal saline solution at 37 degrees C from 41+/-11.9 ml/min to 75.3+/-18.9 ml/min (p < 0.0001).

After harvesting the graft, regaining physiological normothermic state is enough for vasodilatation. Even using one of the most potent vasodilating agent papaverine at 20 degrees C is not superior to normothermia.