Leonard Steinberg, MD Timothy Knilans, MD The Heart Center Children’s Hospital Medical Center

The diagnosis and management of supraventricular tachycardia in

infantsPart II: Management options

Leonard Steinberg, MDTimothy Knilans, MD

The Heart CenterChildren’s Hospital Medical Center

Cincinnati, OH

Overview

Commonly available pharmacotherapies

Acute management

Subacute management

Chronic management

Radiofrequency ablation

Therapy: commonly used drugs

Class I: sodium channel blockers procainamide flecainide

Class II: ß-blockers propranolol esmolol

Class III amiodarone sotalol

Class IV: Ca channel blockers verapamil

Miscellaneous digoxin adenosine

Drugs: class IA (procainamide)

Action: slows conduction and prolongs refractoriness in

muscle, specialized conduction tissue, and accessory pathways

Indications atrial re-entry: atrial fibrillation, atrial flutter accessory pathway tachycardia, particularly if

short RPConsiderations

rapid metabolism > frequent dosing serum concentrations and ECG’s faster ventricular rates negative inotropy

Drugs: class IC (flecainide)

Action slows conduction in muscle, conduction

tissue, and AP’s suppresses automaticity

Indications primary atrial tachycardias (reentrant and

automatic) accessory pathway tachycardia, particularly

if short RPConsiderations

negative inotropy faster ventricular rates proarrhythmia serum concentrations and ECG’s

ensure proper dosingavoid in structural heart defects

Drugs: class II (propranolol)

Action suppresses automaticity (and ectopy) slows AV node conduction and prolongs

refractorinessIndications

automatic atrial tachycardia all reentrant tachycardias (reduces inciting

events)Considerations

QID dosing negative inotropy systemic effects

Drugs: class II (esmolol)

Action suppresses automaticity (and ectopy) slows AV node conduction and prolongs

refractorinessIndications

automatic atrial tachycardia all reentrant tachycardias (reduces inciting

events)Considerations

very short half life negative inotropy systemic effects

Drugs: class III (amiodarone)

Action slows conduction and prolongs

refractoriness in all cardiac tissues suppresses automaticity

Indications second choice therapy for many

arrhythmias primary choice under special circumstances

Considerations no negative inotropy – proarrhythmia multiple systemic effects – long half

life

Drugs: class III (sotalol)

Action prolongs conduction and refractoriness

in all cardiac tissues suppresses automaticity

Indications second (and possibly 1st) choice for

many arrhythmiasConsiderations

proarrhythmia

Drugs: class IV (verapamil)

Action Prolongs conduction and recovery in AV

nodeIndications

? AV node reentry tachycardiaConsiderations

Circulatory collapse in infants

Drugs: digoxin

Action prolongs conduction of AV node shortens conduction and refractoriness of

muscle and accessory pathwaysIndications

reentrant tachycardias involving the AV node

rate control in primary atrial tachycardiaConsiderations

avoid in WPW positive inotropy

Drugs: adenosine

Action impairs conduction in AV node (and

some accessory pathways)Indications

acute termination of AV node dependent reentrant tachycardia

diagnosis of SVTConsiderations

very short half life use with caution in patients on

bronchodilators atrial fibrillation

Acute therapy

Vagal maneuversAdenosineAtrial pacingD/C cardioversionChronic (or sub-acute) therapyAddress underlying metabolic and

hemodynamic derangements

Always perform with continuous rhythm recording

Acute therapy: adenosine and vagal maneuvers

Indicated in AV nodal dependent tachycardias

Adenosine may terminate reentrant atrial tachycardias

No therapeutic benefit in automatic tachycardias

Save vagal maneuvers for known diagnosisAdenosine response accessory pathwayWatch for adenosine side effects

Acute therapy: atrial pacing

Esophageal or post op atrial pacing wires

Termination of reentrant SVTDiagnostic toolNo termination of automatic tachycardiaOverdrive pacing of automatic junctional

tachycardia

EquipmentArrhythmias

Acute therapy: D/C cardioversion

Indicated for conversion of all reentrant tachycardias

First choice for hemodynamically unstable patient

0.5 Joules/kg for most SVT1 Joule/kg for atrial fibrillationUse previously required energy for

repeat cardioversion

Anterior posterior orientation

Sub-acute therapy: IV drugs

Esmolol automatic atrial tachycardia

Procainamide atrial and AV reentrant tachycardia

Digoxin primary atrial tachycardias (rate control) occasionally for AV node dependent

tachycardiasAmiodarone

tachycardias traditionally difficult to treat second line therapy severely depressed function

Chronic therapy: who to treat

No predictors of recurrence

ALL patients require close follow- up

Treat

•Poor function •Recurrent tachycardia

•Hemodynamic compromise•Structural heart disease

•SocialDon’t treat

•Well tolerated•Normal function•No recurrences

•Social

Automatic atrial tachycardia

Suppress automaticityControl ventricular rate

Propranolol Flecainide Sotalol

Special circumstances

Amiodarone

+/– Digoxin

Goals Drugs

“Reasonable” control may be a satisfactory

endpoint

Consideration

Reentrant atrial tachycardia

Suppress ectopyPrevent reentryControl ventricular rate

Propranolol Flecainide Procainamide Sotalol

Special circumstances

Amiodarone

+/– Digoxin

Goals Drugs

AV reentry tachycardia

Goals Drugs

Avoid digoxin when accessory pathway conducts antegrade

Suppress ectopyAttack pathway limb

Propranolol Digoxin Flecainide (short RP) Procainamide (short RP) Sotalol

Special circumstances

Amiodarone

Goals Drugs

Consideration

PJRT(permanent form of junctional reciprocating tachycardia)

Goals Drugs

May be refractory to multiple therapies

Suppress ectopyPrevent reentry

Propranolol Digoxin Flecainide Sotalol Amiodarone

Goals Drugs

Consideration

AV node reentry tachycardia

Suppress automaticityAttack AV node

Propranolol Digoxin Sotalol

Special circumstances

?? Verapamil Amiodarone

Goals Drugs

Automatic junctional tachycardia

Restore AV synchronySuppress automaticity

drugs reduce fever (post op) reduce catecholamine

state (post op)

Considerations

Amiodarone Flecainide Sotalol Procainamide +hypothermia

Goals Drugs

Life threatening tachycardiaVery difficult to treatPost op option: ECMOCongenital option: RFA

Considerations

Atrial fibrillation

Prevent re-entryControl ventricular rateEvaluate for congenital heart diseaseTreat metabolic and hemodynamic derangements

Amiodarone +/- Digoxin

Goals Drugs

Look for structural heart diseaseConsiderations

Chaotic atrial tachycardia

DigoxinPropranolol caution with lung disease

Goals

• Evaluate for respiratory illnesses, esp RSV• Tachycardia unlikely to recur once

respiratory illness resolves

Suppress automaticityControl ventricular rate

Goals Drugs

Considerations

Choosing a drug: other considerations

Use what works

Low threshold for in-patient monitoring

Digoxin & amiodarone do not depress function

START SAFE

Length of therapy

Indications ??Most would treat through the first year of

lifeHolter and event monitors helpfulInducibility ??Natural history favors discontinuing therapy

Therapy: radiofrequency ablation

No long term data in humans

No definitive indications established

WaitProceed

•Refractory tachycardia Hemodynamic compromise

±Hemodynamic catheterization•Impending loss of catheter

access

•Expanding lesions•Higher complication rate

•Natural history

Summary

Therapy for SVT in infants can be divided into acute, sub-acute, chronic, and RF ablation

Acute interventions should be performed with continuous rhythm monitoring to assist in diagnosis

Use sub acute therapy when acute therapies fail

Individualize chronic therapy to the infant and the tachycardia mechanism

RF ablation rarely indicated