Chapter 8  ·  Module 9

Supraventricular Tachycardia: Classification, Management, and Catheter Ablation

Classification, adenosine as diagnostic tool, Wolff-Parkinson-White emergency, wide-complex tachycardia, and ablation outcomes

Supraventricular Tachycardia Classification and Adenosine Response

Atrioventricular Nodal-Dependent

Atrioventricular Nodal Reentrant Tachycardia / Atrioventricular Reentrant Tachycardia

  • Re-entrant circuit requires atrioventricular node as obligate limb
  • Adenosine TERMINATES -- confirms atrioventricular nodal dependence
  • Atrioventricular nodal reentrant tachycardia: re-entry within atrioventricular node; pseudo-R prime in V1; most common (60%)
  • Atrioventricular reentrant tachycardia: accessory pathway circuit; Wolff-Parkinson-White; delta wave in sinus rhythm
  • Acute management: vagal maneuvers first; adenosine; verapamil or diltiazem second-line
  • Ablation curative: atrioventricular nodal reentrant tachycardia over 95%; atrioventricular reentrant tachycardia 93 to 95%

Atrial Origin

Atrial Flutter / Focal Atrial Tachycardia

  • Circuit does NOT require atrioventricular node -- originates entirely in atria
  • Adenosine SLOWS rate but does not terminate -- atrial circuit continues
  • Atrial flutter: sawtooth pattern; 300 bpm atrial rate; 150 bpm ventricular rate (2:1 block); harder to rate-control than atrial fibrillation
  • Focal atrial tachycardia: discrete atrial focus; morphologically distinct P wave; automatic or triggered mechanism
  • Ibutilide most effective pharmacologic cardioversion for atrial flutter
  • Cavotricuspid isthmus ablation curative for typical atrial flutter (over 95%)

Critical Safety Rules

Wolff-Parkinson-White Emergency

Pre-Excited Atrial Fibrillation

  • Accessory pathway conducts atrial fibrillation at 200 to 300+ beats per minute -- risk of ventricular fibrillation
  • Electrocardiogram: irregularly irregular, wide and variable QRS, very rapid rate
  • CONTRAINDICATED: adenosine, verapamil, diltiazem, digoxin, beta-blockers -- all accelerate accessory pathway conduction
  • CORRECT TREATMENT: intravenous procainamide (blocks accessory pathway directly) or intravenous ibutilide
  • Hemodynamically unstable: immediate synchronized direct-current cardioversion
  • Definitive cure: catheter ablation of the accessory pathway

Wide-Complex Tachycardia

Treat as Ventricular Tachycardia Until Proven Otherwise

  • Ventricular tachycardia accounts for 80% of wide-complex tachycardia (over 90% in structural heart disease)
  • Electrocardiogram features confirming ventricular tachycardia: atrioventricular dissociation; fusion beats; capture beats; northwest axis
  • NEVER give verapamil -- causes collapse in ventricular tachycardia; causes ventricular fibrillation in pre-excited atrial fibrillation
  • Safe for both ventricular tachycardia and supraventricular tachycardia with aberrancy: procainamide, amiodarone, direct-current cardioversion
  • Confirmed supraventricular tachycardia with aberrancy: adenosine, verapamil, diltiazem acceptable

Catheter Ablation -- Outcomes by Arrhythmia Type

Arrhythmia Procedure Acute Success Key Points
Atrioventricular nodal reentrant tachycardia Slow pathway modification (radiofrequency or cryo) Over 95%; recurrence 1 to 3% Class I guideline; cryoablation reduces complete atrioventricular block risk to below 0.1%; radiofrequency risk 0.5 to 1%
Atrioventricular reentrant tachycardia / Wolff-Parkinson-White Accessory pathway ablation 93 to 95% overall; higher for left free wall pathways Class I for symptomatic Wolff-Parkinson-White; eliminates pre-excited atrial fibrillation risk; drugs cannot reliably achieve this
Typical atrial flutter Cavotricuspid isthmus ablation 95 to 97%; 90 to 95% at one year Highest success rate of any ablation procedure; Class I for symptomatic typical flutter; rate control pharmacologically difficult
Paroxysmal atrial fibrillation Pulmonary vein isolation 60 to 80% at one year (single procedure) Repeat procedures: 75 to 90%; persistent atrial fibrillation lower (40 to 60%); first-line in atrial fibrillation with heart failure with reduced ejection fraction (CASTLE-AF)

The Adenosine Rule and the Verapamil Rule

Adenosine terminates atrioventricular nodal-dependent tachycardias (atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia) and slows but does not terminate atrial tachycardias (flutter, focal atrial tachycardia, atrial fibrillation) -- this response is both therapeutic and diagnostic. Verapamil is contraindicated in any wide-complex tachycardia of uncertain origin: it causes cardiovascular collapse in ventricular tachycardia and can precipitate ventricular fibrillation in pre-excited atrial fibrillation. Treat wide-complex tachycardia as ventricular tachycardia until proven otherwise.