What is the treatment for AV (atrioventricular) nodal reentrant tachycardia?

Treatment of AV Nodal Reentrant Tachycardia

For acute AVNRT, start with vagal maneuvers immediately, followed by adenosine if unsuccessful; for long-term management, catheter ablation of the slow pathway is the definitive treatment, with calcium channel blockers or beta-blockers reserved for patients who decline or are not candidates for ablation. 1

Acute Treatment Algorithm

First-Line: Vagal Maneuvers

• Perform vagal maneuvers as the initial intervention in hemodynamically stable patients 1
• Have the patient perform Valsalva maneuver in the supine position by bearing down against a closed glottis for 10-30 seconds, generating at least 30-40 mm Hg of intrathoracic pressure 1
• Alternatively, apply unilateral carotid sinus massage for 5-10 seconds after confirming absence of carotid bruit by auscultation 1
• Another effective technique involves applying an ice-cold, wet towel to the face to trigger the diving reflex 1
• Success rate with vagal maneuvers is approximately 27.7% when switching between techniques 1

Second-Line: Adenosine

• Adenosine is the drug of choice for terminating AVNRT, with approximately 95% success rate 1
• Administer as rapid IV bolus followed immediately by saline flush: start with 3 mg, then 6 mg after 1-2 minutes if ineffective, followed by maximum dose of 12 mg 1
• Adenosine selectively blocks AV nodal conduction with an extremely short half-life of less than 10 seconds 1, 2
• Can be safely combined with beta-blockers without causing myocardial depression 1
• Critical caveat: Avoid adenosine in asthmatics as it can precipitate bronchospasm 1
• Common transient side effects include flushing, chest pain, and dyspnea lasting less than 60 seconds 1, 2
• Must be administered in monitored environment (ED, ICU) due to risk of transient complete heart block 1
• Effect is enhanced by dipyridamole and reduced by theophylline 1

Third-Line: IV Calcium Channel Blockers or Beta-Blockers

• IV diltiazem or verapamil are reasonable alternatives in hemodynamically stable patients, with 80-98% success rates 1
• Verapamil dosing: 5-10 mg (0.075-0.1 mg/kg) IV over 60 seconds, can repeat 5 mg bolus to maximum 15-20 mg 1, 3
• Diltiazem is more effective than esmolol for SVT termination 1
• Never use verapamil or diltiazem if patient has taken beta-blockers due to risk of profound bradycardia and hypotension 1
• These agents are negatively inotropic and should be avoided in suspected systolic heart failure 1

Fourth-Line: IV Amiodarone

• Consider IV amiodarone only when other therapies are ineffective or contraindicated in hemodynamically stable patients 1
• Dose: 5 mg/kg (300 mg) over one hour; in life-threatening situations can give over 15 minutes 1
• Antiarrhythmic effect may take up to 30 minutes, making it suboptimal as first-line therapy 1

Cardioversion

• Perform immediate synchronized cardioversion in hemodynamically unstable patients when adenosine and vagal maneuvers fail or are not feasible 1
• Also indicated in hemodynamically stable patients when pharmacological therapy fails or is contraindicated 1
• Highly effective with success rates approaching 100% for SVT termination 1

Long-Term Management Algorithm

Definitive Treatment: Catheter Ablation

• Catheter ablation of the slow pathway is the recommended definitive treatment for AVNRT 1
• Offers curative therapy with high success rate and minimal risk of AV block 4, 5
• Slow pathway ablation is preferred over fast pathway ablation due to lower risk of complete heart block 5
• Rapidly becoming first-choice therapy for symptomatic AVNRT requiring treatment 4, 5

Medical Management (For Patients Declining or Not Candidates for Ablation)

First-Line Pharmacological Options:

• Oral verapamil or diltiazem are recommended as first-line medical therapy 1
• Oral beta-blockers are equally recommended as first-line agents 1
• Digoxin alone or combined with beta-blockers is effective in approximately 50% of cases 3

Second-Line Options:

• Flecainide or propafenone are reasonable in patients without structural heart disease or ischemic heart disease when first-line agents are ineffective or contraindicated 1
• FDA-approved indication: flecainide is indicated for prevention of PSVT including AVNRT in patients without structural heart disease 6
• Critical warning: Never use flecainide in patients with recent myocardial infarction or structural heart disease due to proarrhythmic effects 6

Third-Line Options:

• Oral sotalol or dofetilide may be reasonable when other agents fail 1
• Oral digoxin or amiodarone may be considered as last-resort options 1

Observation Without Treatment

• Clinical follow-up without pharmacological therapy or ablation is reasonable for minimally symptomatic patients 1

Key Clinical Pearls

• AVNRT is the most common SVT, typically occurring in young adults without structural heart disease, with >60% in women 1
• Ventricular rate typically ranges 180-200 bpm but can vary from 110 to >250 bpm 1
• Patients characteristically report palpitations in the neck during attacks 4
• On ECG, P waves are typically obscured by QRS or appear as discrete waves immediately after QRS, or show rSr' pattern in V1 4
• The reentrant circuit involves dual AV nodal pathways with different electrophysiological properties (fast and slow pathways) 4, 5