| Abstrakt: |
Deep hypothermia with total circulatory arrest is an important technique in the surgical treatment of complex congenital heart defects. The effects of propranolol on cerebral electrical activity in lambs undergoing a 90-minute period of circulatory arrest after initial surface cooling to 26° C and subsequent core cooling to 15° C was studied by means of the cerebral function analyzing monitor. Five of the lambs were pretreated with intravenous propranolol 0.2 mg/kg (group I) and five acted as controls (group II). The surface cooling phase was associated with a continuous decrease in mean electroencephalographic voltage ± standard error, which decreased from 82.8 ± 11.8 μV at 37° C to 31.6 ± 2.4 μV at 26° C in the control group compared with 75.0 ± 7.4 μV and 63.2 ± 9.2, respectively, in the propranolol group (p< 0.05). During the rewarming phase, the latency to (1) initial appearance of electrical activity, (2) continuous recording with the cerebral function analyzing monitor, and (3) maximum voltage and frequency recovery was 2.0 ± 1, 5.9 ± 4, and 32.4 ± 8 minutes in the propranolol group, which was significantly (p ≤0.01) shorter than in the control group (18.4 ± 3, 38.2 ± 5, and 111.0 ± 9 minutes, respectively). These results suggest that pretreatment with propranolol may play an important part in the brain tolerance to deep hypothermia and circulatory arrest. |
