[Study of mechanism of vasoplegic syndrome for open heart surgery]

To study the mechanism of vasoplegic syndrome after cardiac surgery.

Twenty-four rabbits were anesthesized intravenously. Pulmonary artery, renal artery, and carotid artery were isolated and arterial rings with the length of 3.0 mm, 8 rings for each artery, were resected and incubated in Kreb solution at temperature of 37 degrees C for one hour. The intactness of endothelium of arterial rings was examined. Those losing intactness were abandoned. The change of angiostasis at different temperatures was recorded with vascular tone software. The arterial rings of different groups were incubated in Kreb solution at the temperatures of 37 degrees C, 30 degrees C and 24 degrees C for 30 minutes. Noradrenalin of different concentrations was added into the solution at different temperatures. And then the angiostasis was recorded.

At low temperature, the vascular tone of the three arteries (Fpulmonary artery = 69.909, Frenal artery = 131.192, Fcarotid artery = 50.663, P < 0.001) and contraction in response to noradrenline of pulmonary artery (F = 269.121, P < 0.001), renal artery (F = 250.535, P < 0.001) and carotid artery (F = 250.535, P < 0.001) were lower than at normal temperature.

Hypothermia may be one of the causes of vasoplegic syndrome after cardiac surgery.