A 27-year-old man with no prior cardiac history presents with regular narrow-complex tachycardia. Vital signs show HR 180 bpm, BP 95/60 mmHg, RR 20, SpO2 98% on room air. He receives intravenous adenosine and briefly experiences flushing and substernal chest discomfort before the rhythm terminates to normal sinus rhythm. ECG demonstrates no delta waves or evidence of preexcitation. Which of the following best describes the mechanism of this medication?
- A)Blocks delayed rectifier potassium channels throughout the ventricle
- B)Inhibits Na-K-2Cl cotransport in the thick ascending limb
- C)Blocks fast sodium channels in ventricular myocardium
- D)Increases vagal tone and transiently blocks AV nodal conductionGABARITO
- E)Stimulates beta-1 receptors in the AV node
Explicação
Adenosine activates A1 receptors, causing increased outward potassium current and decreased calcium current in the AV node. This transiently blocks AV nodal conduction and terminates many AV node-dependent supraventricular tachycardias. Ver explicação completa e trilha adaptativa →