Algorithm for the acute treatment of atrioventricular nodal reentrant tachycardia

AVNRT: atrioventricular nodal reentrant tachycardia; IV: intravenous; ECG: electrocardiogram; CCB: calcium channel blocker; ACLS: advanced cardiac life support; BB: beta blocker.
* Evidence of hemodynamic instability may include hypotension, altered mental status, or signs and symptoms of chest pain or heart failure. If patient becomes hemodynamically unstable at any point, proceed with electrical cardioversion.
¶ If initial low-energy shock is unsuccessful, subsequent shocks should be attempted using higher energy levels. The exact energy level varies depending upon the type of defibrillator (ie, biphasic versus monophasic). Patients should be sedated and monitored when undergoing electrical cardioversion.
Δ Most patients who remain hemodynamically stable and who are able to participate in vagal maneuvers should perform several attempts prior to pharmacologic therapy.
◊ Adenosine is administered by rapid IV injection over one to two seconds at a peripheral site, followed by a normal saline flush. The rapid administration of both the drug and the saline flush is most easily accomplished through a three-way stopcock. The usual initial dose is 6 mg, which can be followed by a dose of 12 mg if not successful. A dose of 18 mg can be used if 12 mg fails to convert the patient to sinus rhythm. Repeated dosing beyond the 18 mg bolus is not usually effective.
§ Adenosine can be readministered immediately, for up to three doses, if AVNRT reoccurs. If AVNRT continues to recur following successful termination(s) with adenosine, a second drug should be administered (eg, BB or CCB) in an attempt to suppress the arrhythmia.
¥ The choice between BB and CCB is usually based on familiarity with and availability of the particular agents. Typical options and doses include:

• Verapamil 5 to 10 mg IV bolus over two minutes; if no response, an additional 10 mg IV bolus may be administered 15 to 30 minutes following the initial dose.
• Diltiazem 0.25 mg/kg (average dose 20 mg) IV bolus over two minutes; if no response, an additional 0.35 mg/kg (average dose 25 mg) IV bolus may be administered 15 to 30 minutes following the initial dose.
• Metoprolol 2.5 to 5 mg IV bolus over two to five minutes; if no response, an additional 2.5 to 5 mg IV bolus may be administered every 10 minutes to a total dose of 15 mg.

‡ Refer to UpToDate content on advanced cardiac life support.
† Diagnostic testing is usually indicated following the initial presentation with AVNRT or in patients with signs/symptoms of concurrent angina or heart failure. Stable patients can undergo diagnostic testing in an outpatient environment. Refer to UpToDate topics for diagnostic approach.
** Preventive therapy may include no specific treatment, pharmacologic suppression, or catheter ablation depending upon the frequency of AVNRT, severity of associated symptoms, and patient preference.