Coronary artery tourniquet and shunting: acute effects and wall damage Free

We read with great interest the article by Wippermann and associates [1]. Wippermann and coauthors analysed the coronary artery wall and endothelial damages provoked by tourniquet occlusion and intraluminal shunt in an experimental off-pump surgery animal model. In a group of six pigs, the left anterior descending (LAD) was snared and tightened for 20 min, while in another group of six pigs, the LAD was shunted and after 20 min of reperfusion the shunt was removed and the coronary artery repaired. The authors observed that none of the untreated coronary artery segments exhibited endothelial lesions larger than grade II; at light microscopy, five of the snared group and three of the shunted group showed intimal damages, and all six of the snared group and two of the shunted group had signs of endothelial abrasion at scanning electron microscopy. Therefore, they concluded that shunting is less traumatic than tourniquet snaring in off-pump surgery, although careful manipulation is essential to limit underhand complications. The stated limitation of their study was essentially the health coronary artery tree, thus the lack of native atherosclerotic lesions pre-disposing further intimal injuries. The authors overcome this limitation discussing that Hangler et al. [2] obtained similar results, testing the snaring effect on coronary artery of patients affected by ischemic cardiomyopathy prior to heart transplantation.

After informed consent was obtained and prior to heart transplantation, we have used as model to test the effects of these devices the LAD of eight patients affected by post-ischemic dilated cardiomyopathy [3]. Opposed to Hangler, who snared the coronary vessels during cardiopulmonary bypass, thus with an unloaded heart, we snared, opened, and shunted the LAD with a beating heart mimicking a real off-pump coronary artery bypass (OPCAB) procedure. Shunting always determined a brushing effect with grade II injuries, and the more atherosclerotic vessel the larger endothelial denudation effect [3]. On the contrary, snares used gently around the coronary artery to occlude the vessel appeared to achieve effective haemostasis, when tightened around an atherosclerotic or fibrotic coronary artery segment we observed an endothelial cell loss and atherosclerotic plaque fracture (grade III).

In conclusion, we think that shunting and snaring during OPCAB are both at risk, and the more diseased atherosclerotic vessel is the higher is the damage to the coronary wall during vessel manipulation. Therefore, full knowledge of the effect of these devices is advisable and these human and animal, acute experimental and chronic studies are all welcome.

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