Transcript Diagnosis and Management of Supraventricular

The diagnosis and management of
supraventricular tachycardia in
infants
Part II: Management options
Leonard Steinberg, MD
Timothy Knilans, MD
The Heart Center
Children’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 RP
Considerations




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 RP
Considerations




negative inotropy
faster ventricular rates
proarrhythmia
serum concentrations and ECG’s
ensure proper dosing
avoid in structural heart defects
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
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
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 arrhythmias
Considerations
 proarrhythmia
Drugs: class IV (verapamil)
Action
 Prolongs conduction and recovery in AV
node
Indications
 ? AV node reentry tachycardia
Considerations
 Circulatory collapse in infants
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
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
Acute therapy
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: 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
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
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
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
Chronic therapy: who to treat
•Poor function
•Recurrent tachycardia
•Hemodynamic compromise
•Structural heart disease
•Social
•Well tolerated
•Normal function
•No recurrences
•Social
Don’t treat
Treat
No predictors of recurrence
Automatic atrial tachycardia
Goals
Drugs
Suppress automaticity
Control ventricular rate
Propranolol
Flecainide
Sotalol
Special circumstances
Consideration
Amiodarone
“Reasonable” control
may be a satisfactory
endpoint
+/– Digoxin
Reentrant atrial tachycardia
Goals
Drugs
Suppress ectopy
Prevent reentry
Control ventricular rate
Propranolol
Flecainide
Procainamide
Sotalol
Special circumstances
Amiodarone
+/– Digoxin
AV reentry tachycardia
Goals
Drugs
Suppress ectopy
Attack pathway limb
Propranolol
Digoxin
Flecainide (short RP)
Procainamide (short RP)
Sotalol
Consideration
Special circumstances
Avoid digoxin when
accessory pathway
conducts antegrade
Amiodarone
Goals
Drugs
PJRT
(permanent form of junctional reciprocating tachycardia)
Goals
Drugs
Suppress ectopy
Prevent reentry
Propranolol
Digoxin
Flecainide
Sotalol
Amiodarone
Goals
Drugs
Consideration
May be refractory to multiple therapies
AV node reentry tachycardia
Goals
Drugs
Suppress automaticity
Attack AV node
Propranolol
Digoxin
Sotalol
Special circumstances
?? Verapamil
Amiodarone
Automatic junctional
tachycardia
Goals
Drugs
Restore AV synchrony
Suppress automaticity
Amiodarone
Flecainide
Sotalol
Procainamide
+hypothermia
 drugs
 reduce fever (post op)
 reduce catecholamine
state (post op)
Considerations
Considerations
Life threatening tachycardia
Very difficult to treat
Post op option: ECMO
Congenital option: RFA
Atrial fibrillation
Goals
Drugs
Prevent re-entry
Control ventricular rate
Evaluate for congenital
heart disease
Treat metabolic and
hemodynamic
derangements
Amiodarone
+/- Digoxin
Considerations
Look for structural heart disease
Chaotic atrial tachycardia
Goals
Drugs
Suppress automaticity
Control ventricular rate
Digoxin
Propranolol
Goals
 caution with lung disease
Considerations
• Evaluate for respiratory illnesses, esp RSV
• Tachycardia unlikely to recur once
respiratory illness resolves
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
life
Holter and event monitors helpful
Inducibility ??
Natural history favors discontinuing therapy
Therapy:
radiofrequency ablation
•Expanding lesions
•Higher complication rate
•Natural history
•Refractory tachycardia
Hemodynamic compromise
±Hemodynamic catheterization
•Impending loss of catheter
access
Proceed
Wait
No long term data in humans
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