Arritmias na sala de emergência e UTI. Taquicardias de QRS estreito: fundamentos para a abordagem / Arrythmias in the emergency room and ICU Narrow QRS rachycardias: bases for clinical approach

As taquicardias de QRS estreito apresentam origem supraventricular. O histórico clínico, exame físico e eletrocardiograma na sala de emergência constituem-se nas principais ferramentas para o tratamento do quadro. As taquicardias que apresentam instabilidade hemodinâmica devem ser, imediatamente, revertidas através de cardioversão elétrica sincronizada. Aquelas que se apresentam como estáveis hemodinamicamente podem, se regulares, ser tratadas através de manobras vagais ou através do uso de fármacos endovenosos. Se irregulares, podem caracterizar fibrilação e flutter atrial, sendo, então, avaliados a duração do episódio e o risco de tromboembolismo para determinar não apenas a necessidade de anticoagulação, mas também a estratégia para tratamento do quadro, seja através do controle da frequência cardíaca ou do controle do ritmo, este último podendo ser alcançado através do uso de fármacos (propafenona oral ou amiodarona endovenosa) ou da cardioversão elétrica sincronizada. Dessa forma, o papel do clínico na sala de emergência é fundamental para garantir a condução adequada dos episódios de taquicardia supraventricular, especialmente, na prevenção ou pronta intervenção em caso de deterioração hemodinâmica relacionada ao quadro

Narrow QRS tachycardias are supraventricular in origin. The clinical history, physical exam, and electrocardiogram in the emergency room are the main tools used to manage this condition. Tachycardias that present haemodynamic instability must be promptly reverted through synchronized electrical cardioversion. Those that present haemodynamic stability may be treated with vagal maneuvers or intravenous drugs. If irregular, they may take the form of atrial fibrillation or atrial flutter, and in this case, the duration of the episode and the thromboembolic risk are evaluated to determine not only the need for anticoagulation, but also the treatment strategy, whether through heart rate or rhythm control. The latter may be achieved through the use of drugs (oral propafenone or intravenous amiodarone) or synchronized electrical cardioversion. The role of the clinician in the emergency room is therefore fundamental in ensuring adequate conduct of episodes of supraventricular tachycardia, especially in prevention or prompt intervention in case of haemodynamic deterioration related to the condition

Propafenone in experimentally induced acute myocardial infarction

In the present work, the effect of propafenone on experimental acute myocardial ischemia induced by either total left coronary artery [LCA] ligation [persistent and transient for 30 and 60 minutes] or by s.c. injection of isoprenaline [300 mg/kg] was investigated in albino rats. Propafenone was given as a single selected for evaluation of the severity of ischemia and the effect of propafenone were the voltage of T-wave, the heart rate, the CK-MB enzyme serum level and the percent of infarct area. In addition, the effect of propafenone on the coronary outflow in vitro was, also, investigated on the rabbit heart. The present work demonstrated that propafenone produced significant decrease in almost all examined parameters, when it was given before or after induction of ischemia. However, pretreatment with propafenone produced significantly greater effects as compared with those produced when the drug was administered after induction of ischemia. Such finding suggested a protective rather than a curative effect for propafenone against myocardial damage caused by ischemia. Investigating the effect of propafenone on the isolated perfused rabbit heart revealed a significant increase in the coronary outflow, which could, in part, explain the cardioprotective effect of this drug in myocardial ischemia