cardiovascular disorders
Medications for Arrhythmias
Class II Antiarrhythmic Drugs
Class II antiarrhythmic drugs are the Beta-blockers Beta-blockers affect predominantly slow-channel tissues (sinoatrial and atrioventricular nodes), where they decrease rate of automaticity, slow conduction velocity, and prolong refractoriness. Thus, heart rate is slowed, the PR interval is lengthened, and the AV node transmits rapid atrial depolarizations at a lower frequency. Class II drugs are used primarily to treat Reentrant Supraventricular Tachycardias (SVT) Including Wolff-Parkinson-White Syndrome , including sinus tachycardia, and to slow the ventricular response rates to Beta-blockers are generally well tolerated; adverse effects include lassitude, sleep disturbance, and gastrointestinal upset. These drugs are contraindicated in patients with asthma. 