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

1. The diagnosis and management of supraventricular tachycardia in infantsPart II: Management options Leonard Steinberg, MD Timothy Knilans, MD The Heart Center Children’s Hospital Medical Center Cincinnati, OH

2. Overview • Commonly available pharmacotherapies • Acute management • Subacute management • Chronic management • Radiofrequency ablation

3. 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 Therapy: commonly used drugs

4. 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 RP • Considerations • rapid metabolism > frequent dosing • serum concentrations and ECG’s • faster ventricular rates • negative inotropy

5. 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 RP • Considerations • negative inotropy • faster ventricular rates • proarrhythmia • serum concentrations and ECG’s ensure proper dosing avoid in structural heart defects

6. Drugs: class II (propranolol) • Action • suppresses automaticity (and ectopy) • slows AV node conduction and prolongs refractoriness • Indications • automatic atrial tachycardia • all reentrant tachycardias (reduces inciting events) • Considerations • QID dosing • negative inotropy • systemic effects

7. Drugs: class II (esmolol) • Action • suppresses automaticity (and ectopy) • slows AV node conduction and prolongs refractoriness • Indications • automatic atrial tachycardia • all reentrant tachycardias (reduces inciting events) • Considerations • very short half life • negative inotropy • systemic effects

8. 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

9. Drugs: class III (sotalol) • Action • prolongs conduction and refractoriness in all cardiac tissues • suppresses automaticity • Indications • second (and possibly 1st) choice for many arrhythmias • Considerations • proarrhythmia

10. Drugs: class IV (verapamil) • Action • Prolongs conduction and recovery in AV node • Indications • ? AV node reentry tachycardia • Considerations • Circulatory collapse in infants

11. Drugs: digoxin • Action • prolongs conduction of AV node • shortens conduction and refractoriness of muscle and accessory pathways • Indications • reentrant tachycardias involving the AV node • rate control in primary atrial tachycardia • Considerations • avoid in WPW • positive inotropy

12. Drugs: adenosine • Action • impairs conduction in AV node (and some accessory pathways) • Indications • acute termination of AV node dependent reentrant tachycardia • diagnosis of SVT • Considerations • very short half life • use with caution in patients on bronchodilators • atrial fibrillation

13. Vagal maneuvers Adenosine Atrial pacing D/C cardioversion Chronic (or sub-acute) therapy Address underlying metabolic and hemodynamic derangements Always perform with continuous rhythm recording Acute therapy

14. 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 diagnosis • Adenosine response  accessory pathway • Watch for adenosine side effects

15. Acute therapy: atrial pacing • Esophageal or post op atrial pacing wires • Termination of reentrant SVT • Diagnostic tool • No termination of automatic tachycardia • Overdrive pacing of automatic junctional tachycardia • Equipment • Arrhythmias

16. Acute therapy: D/C cardioversion • Indicated for conversion of all reentrant tachycardias • First choice for hemodynamically unstable patient • 0.5 Joules/kg for most SVT • 1 Joule/kg for atrial fibrillation • Use previously required energy for repeat cardioversion • Anterior posterior orientation

17. 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 tachycardias • Amiodarone • tachycardias traditionally difficult to treat • second line therapy • severely depressed function

18. Chronic therapy: who to treat ALL patients require close follow- up • Well tolerated • Normal function • No recurrences • Social • Poor function • Recurrent tachycardia • Hemodynamic compromise • Structural heart disease • Social Don’t treat Treat No predictors of recurrence

19. Suppress automaticity Control ventricular rate Propranolol Flecainide Sotalol Special circumstances Amiodarone +/– Digoxin Automatic atrial tachycardia Goals Drugs Consideration “Reasonable” control may be a satisfactory endpoint

20. Suppress ectopy Prevent reentry Control ventricular rate Propranolol Flecainide Procainamide Sotalol Special circumstances Amiodarone +/– Digoxin Reentrant atrial tachycardia Goals Drugs

21. Suppress ectopy Attack pathway limb Propranolol Digoxin Flecainide (short RP) Procainamide (short RP) Sotalol Special circumstances Amiodarone AV reentry tachycardia Goals Drugs Drugs Goals Consideration Avoid digoxin when accessory pathway conducts antegrade

22. Suppress ectopy Prevent reentry Propranolol Digoxin Flecainide Sotalol Amiodarone PJRT(permanent form of junctional reciprocating tachycardia) Goals Drugs Drugs Goals Consideration May be refractory to multiple therapies

23. Suppress automaticity Attack AV node Propranolol Digoxin Sotalol Special circumstances ?? Verapamil Amiodarone AV node reentry tachycardia Goals Drugs

24. Restore AV synchrony Suppress automaticity drugs reduce fever (post op) reduce catecholamine state (post op) Amiodarone Flecainide Sotalol Procainamide +hypothermia Automatic junctional tachycardia Goals Drugs Considerations Considerations Life threatening tachycardia Very difficult to treat Post op option: ECMO Congenital option: RFA

25. Prevent re-entry Control ventricular rate Evaluate for congenital heart disease Treat metabolic and hemodynamic derangements Amiodarone +/- Digoxin Atrial fibrillation Goals Drugs Considerations Look for structural heart disease

26. Digoxin Propranolol caution with lung disease Chaotic atrial tachycardia Goals Drugs Goals Suppress automaticity Control ventricular rate Considerations • Evaluate for respiratory illnesses, esp RSV • Tachycardia unlikely to recur once respiratory illness resolves

27. Use what works Low threshold for in-patient monitoring Digoxin & amiodarone do not depress function START SAFE Choosing a drug: other considerations

28. Indications ?? Most would treat through the first year of life Holter and event monitors helpful Inducibility ?? Natural history favors discontinuing therapy Length of therapy

29. Therapy: radiofrequency ablation No definitive indications established • Refractory tachycardia • Hemodynamic compromise • Hemodynamic catheterization • Impending loss of catheter • access • Expanding lesions • Higher complication rate • Natural history Proceed Wait No long term data in humans

30. 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 Summary