Intérêt des bêta-bloquants en médecine périopératoire. Deuxième partie: indications thérapeutiques

Abstract

Objectif : Rappeler les notions de pharmacologie et de physiopathologie nécessaires à l'utilisation des bêta-bloquants (BB) en médecine péri-opératoire.Sources : Recherche manuelle et informatisée de la littérature (mots-clés : anesthesia and beta-blocker, surgery and beta-blocker).Constatations principales : En chirurgie non cardiaque, des études cliniques ont montré depuis 1979 l'intérêt de poursuivre ce traitement jusqu'à l'anesthésie chez les hypertendus. En 1996, il a été démontré que l'utilisation périopératoire d'aténolol chez les patients coronariens diminuait l'incidence de l'ischémie myocardique et surtout la mortalité dans les deux années postopératoires. En chirurgie coronaire, l'intérêt de la poursuite du traitement BB jusqu'à l'intervention a été montré depuis 1983. Cependant, les posologies utilisées doivent être adaptées à la voie d'administration, au type de chirurgie considéré et à l'état physiologique du patient. Enfin, l'utilisation des BB s'est montrée bénéfique dans certaines situations telles que l'infarctus myocardique ou l'insuffisance cardiaque chronique contrôlée. Conclusion :Les effets bénéfiques des BB sur l'ischémie myocardique, sur le taux de complications cardiaques postopératoires et sur la mortalité sont démontrés. Leur utilisation plus large est donc recommandée.Purpose: To review the pharmacologic and pathophysiologic information necessary to prescribe beta-blockers (BB) in perioperative medicine.Data source: Manual retrieval and electronic research of the literature using MEDLINE (key-words: anesthesia and beta-blocker; surgery and beta-blocker).Data synthesis: In non cardiac surgery, the beneficial effects of BB have been demontrated in hypertensive patients since 1979. In 1996, the beneficial effects of atenolol in patients with coronary artery disease (reduction of postoperative myocardial ischemia and overall reduction in two-year mortality) were demonstrated. In coronary surgery, the interest of preoperative BB treatment has been shown since 1983. Administration of BB has been shown to be beneficial in acute myocardial infarction or chronic cardiac failure (except in NYHA class IV patients).Conclusion: BB have been shown to exert a beneficial effect on postoperative outcomes in patients with cardiovascular disease or risk factors, and their more widespread use in perioperative medicine is encouraged.Intérêt des bêta-bloquants en médecine périopératoire. Deuxième partie: indications thérapeutiques

Beta-bloqueadores em anestesiologia: aspectos farmacológicos e clínicos

“…Contudo, o efeito dos beta-bloqueadores na redução da atividade simpática é proporcional ao nível de tô-nus simpático basal, tendo seus efeitos limitados na ausên-cia de estímulos 1,10 . Por outro lado, episódios de taquicardia, disritmias e hipertensão arterial durante a laringoscopia, intubação e estímulos cirúrgicos dolorosos poderão ser prevenidos pelos beta-bloqueadores 10,32 . Com isso, pode-se evitar aumento do consumo cardíaco de oxigênio, principalmente em coronariopatas.…”

“…No paciente coronariopata, o benefício da utilização de beta-bloqueadores, utilizados antes da intubação traqueal, é também resultado do efeito depressor do miocárdio dessas drogas, com potencial para alterar a função ventricular. Deve-se ser cauteloso em pacientes com angina de Prizmetal, pois o uso de beta-bloqueadores não-seletivos pode provocar episódios de isquemia miocárdica 32 . Nesses pacientes, os bloqueadores de canais de cálcio e os nitratos têm melhor indicação.…”

“…However, beta-blockers effect in decreasing sympathetic activity is a function of the baseline sympathetic tone level and their effects are limited in the absence of stimuli 1,10 . Conversely, tachycardia, arrhythmias and hypertension during laryngoscopy, intubation and surgical painful stimuli may be prevented by beta-blockers 10,32 , thus avoiding an increase in cardiac oxygen consumption, especially in patients with coronary artery disease. Among halogenate agents, only enflurane and halothane seem to exacerbate negative chronotropic and inotropic effects of some beta-blockers, but only in concentrations higher than 1.5 times minimum alveolar concentration (MAC) 1 .…”

“…The benefit of beta-blockers for coronary artery disease patients before tracheal intubation is also result of a myocardial depressing effect of such drugs with potential to change ventricular function. Care must be taken with Prizmetal's angina patients because non-selective beta-blockers may cause myocardial ischemia 32 . For those patients, calcium channel blockers and nitrates are the best indication.…”