[Propranolol protects the myocardium and prevents arterial hypotension in an experimental organ donation model]

To analyze the role that sympathetic nervous system hyperactivity immediately following brain death plays in the cardiovascular dysfunction of an organ donor.

Fifteen New Zealand white rabbits were placed in three groups: a control group, a brain-death group without propranolol and a brain-death group with propranolol. Brain death was caused by severe intracranial hypertension; in the third group propranolol was first perfused intravenously. We recorded hemodynamic (heart rate, number of extrasystoles, central venous pressure, systemic and pulmonary arterial pressure), biochemical (adrenaline, noradrenaline, dopamine and troponin T) and histologic data.

Catecholamine levels rose significantly in both experimental groups after brain death, which coincided with clinical signs of sympathetic hyperactivity in the group not receiving propranolol but not in the group receiving the beta-blocker. The myocardium of animals not receiving the beta-blocker showed myocytolysis, edema, subendocardial bleeding and leukocyte infiltration. Such changes were practically absent in the animals that received beta-blockers. In the beta-blocker group, serum troponin, and index of myocytolysis, rose significantly less than in the non-premedicated group. Blood pressure in all the brain-dead animals was significantly lower than in the control group, but was more severe in animals that had not received propranolol.

Sympathetic nervous system hyperactivity after brain death affects the histology and functioning of the myocardium in this experimental organ donor model. Pretreatment with propranolol prevents damage.