Heart rate changes in cardiac transplant patients and in the denervated cat heart after edrophonium

Autor: Backman, Steven B., Stein, Reuben D., Fox, Gordon S., Polosa, Canio
Zdroj: Canadian Journal of Anesthesia; March 1997, Vol. 44 Issue: 3 p247-254, 8p
Abstrakt: Purpose: The effect of edrophonium on heart rate in cardiac transplant patients and in an animal model of acute cardiac denervation were studied, to evaluate the functional state of the peripheral parasympathetic pathway fol lowing cardiac denervation. Methods: Edrophonium was studied in patients with normally innervated hearts (controls) and m cardiac trans plants. Edrophonium was also studied in vagotomized. beta-blocked cats. In Group I animals, the vagus nerve was not stimulated. In Groups 2 & 3 the right vagus nerve was electrically stimulated to produce approximately 20% and 40% reductions in baseline heart rate, respectively. Results: Maximum heart rate reduction in transplants (7.3 ± 0.8 beats·min−1with 0.6 ± 0.08 mg·kg−1) was less than in controls (13.3 ± 1.6 beatsmm with 0.4 + 0.05 mg·kg−1, P < 0.01). In Group I animals heart rate decreased maximally by 20.9 ± 2.5 beats·min−1with 9.0 ± 1.9 mg·kg−1. In Groups 2 and 3, with doses < 15 mg·kg−1, reduc tions m heart rate were greater than in Group I and maximual reductions were obtained with lower doses (Group 2: maximum reduction by 20.3 ± 2.8 beats·min−1with 1.3 ± 0.1 mg·kg−1: Group 3: 22.6 ± 4.0 beats·min−1with 0.8±0.2 mg·kg−1, P < 0.001) Doses > 1.5 mg·kg−1in Groups 2 and 3 produced increases in heart rate. Conclusion: Edrophonium produced bradycardia in cardiac transplants suggesting spontaneous release of acetylcholinee from parasympathetic postganglionic neurons m the transplanted heart. The magnitude of the brady cardia was less in transplant than in control patients. Findings from animal studies suggest that the reduction in transplants can be attributed to diminution or absence of tonic cardiac parasympathetic drive. At high doses, edrophonium may interfere with parasympathetic neuron activation.
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