This document discusses atrioventricular nodal reentrant tachycardia (AVNRT), which accounts for about 2/3 of paroxysmal supraventricular tachycardia cases. It involves a dual pathway in the AV node that can lead to a reentrant circuit triggered by a premature atrial complex. Management in the acute setting includes vagal maneuvers, adenosine, calcium channel blockers, or cardioversion. Long term management depends on severity and may involve medications like digoxin, beta blockers, calcium channel blockers, or catheter ablation, which has a 95% success rate but 1% risk of AV block.

1. AVNRT 2/3 of all Paroxysmal SVT cases Regular rhythm No discernible P wave or retrograde P wave (Short RP tachycardia) Pathophysiology: Dual AV nodal pathway

2. PAC precipitates reentrant circuit. ECG Concept Using Electrophysiologic Principle

6. Management of AVNRT ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias--executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Supraventricular Arrhythmias). 2003

7. Acute setting Vagal Maneuver Adenosine 90% success rate Calcium channel blocker: terminate in 2 minutes DC cardioversion 10-50 J

10. V1 II

11. Long term management Severity of attack Medication Digoxin Beta blocker Calcium channel blocker

12. Catheter Ablation 95% success rate, 1% chance of AV block Patient preference Fail pharmacologic therapy or side effect from medication Severely symptomatic eg syncope angina dyspnea