cardiovascular disorders
Reentrant Supraventricular Tachycardias (SVT) Including Wolff Parkinson White Syndrome
Treatment of Reentrant SVTs
Vagotonic maneuvers Adenosine Verapamilordiltiazemif narrow, regular QRS complex For frequent recurrence, ablation Many episodes stop spontaneously before treatment. Vagotonic maneuvers(eg, Valsalva maneuver, unilateral carotid sinus massage, ice water facial immersion, swallowing of ice-cold water), particularly if used early, may terminate the tachyarrhythmia; some patients use these maneuvers at home. AV node blockersare used if vagotonic maneuvers are ineffective and the QRS complex is narrow (indicating orthodromic conduction) and regular (indicating the episode is not atrial fibrillation); blocking conduction through the AV node for one beat interrupts the reentrant cycle.Adenosineis the first choice. Dose is 6 mg by rapid IV bolus (0.05 to 0.1 mg/kg in children), followed by a 20-mL saline bolus. If this dosage is ineffective, 2 subsequent 12-mg doses are given every 5 minutes.Adenosinesometimes causes a brief (2- to 3-second) period of cardiac standstill, which may distress patient and physician.Verapamil5 mg IV ordiltiazem0.25 to 0.35 mg/kg IV are alternatives. can be used. Alternatively, Cardiac Resynchronization Therapy (CRT) with 50 joules (0.5 to 2 joules/kg for children) is quick and safe and may be preferred to these more toxic drugs. When episodes of AV nodal reentrant tachycardia are frequent or bothersome, options include long-term antiarrhythmics or transvenous catheter Ablation for Cardiac Arrhythmia . Generally, ablation is recommended, but if it is not acceptable, drug prophylaxis usually begins with 