Supraventricular Tachycardia in Infancy and Childhood Terrence Chun, MD Pediatric Electrophysiology and Pacing

Supraventricular Supraventricular TachycardiaTachycardia

in Infancy and Childhoodin Infancy and Childhood

Terrence Chun, MDTerrence Chun, MD

Pediatric Electrophysiology and PacingPediatric Electrophysiology and Pacing

Cardiac electrical anatomyCardiac electrical anatomy

SVT - OverviewSVT - Overview

Rapid rhythm that involves or is Rapid rhythm that involves or is driven by structures in the upper driven by structures in the upper heartheart

Incidence up to 1:250 childrenIncidence up to 1:250 children Generally well-tolerated, even fast Generally well-tolerated, even fast

ratesrates Risk of life-threatening arrhythmias Risk of life-threatening arrhythmias

is uncommonis uncommon

Narrow vs. Wide QRSNarrow vs. Wide QRS

Not all narrow QRS complex Not all narrow QRS complex tachycardia is supraventricular tachycardia is supraventricular tachycardiatachycardia

Not all wide QRS complex Not all wide QRS complex tachycardia is ventricular tachycardia is ventricular tachycardiatachycardia

SVT Mechanisms - SVT Mechanisms - OverviewOverview

Reentrant rhythmsReentrant rhythms Automatic rhythmsAutomatic rhythms

SVT mechanisms –SVT mechanisms –

Automatic RhythmsAutomatic Rhythms

Originate from a particular focusOriginate from a particular focus ““Warm-up” and “cool-down” behaviorWarm-up” and “cool-down” behavior Respond to drugs and maneuvers Respond to drugs and maneuvers

that affect myocardial automaticitythat affect myocardial automaticity May be suppressed by faster ratesMay be suppressed by faster rates Usually do not respond to Usually do not respond to

cardioversion (typically pause, then cardioversion (typically pause, then restart)restart)


Automatic RhythmsAutomatic Rhythms

Left atrial focusLeft atrial focus 2:1 AVN conduction2:1 AVN conduction


Reentrant rhythmsReentrant rhythms

Requires a “circuit” of tissue to Requires a “circuit” of tissue to create repetitive activationcreate repetitive activation

Must have appropriate conditions to Must have appropriate conditions to perpetuate reentrant rhythmperpetuate reentrant rhythm

Usually abrupt onset and Usually abrupt onset and terminationtermination

Regular, with little variation in rateRegular, with little variation in rate Often will respond to cardioversionOften will respond to cardioversion


Reentrant rhythmsReentrant rhythms

Diagnostic methodsDiagnostic methods

12-lead electrocardiogram ! ! !12-lead electrocardiogram ! ! ! Post-op atrial/ventricular pacing Post-op atrial/ventricular pacing

wireswires Esophageal pacing leadsEsophageal pacing leads Adenosine can be diagnosticAdenosine can be diagnostic Invasive electrophysiology studyInvasive electrophysiology study


AlwaysAlways AlwaysAlways AlwaysAlways record a record a rhythm striprhythm strip

during any intervention during any intervention (adenosine, cardioversion, (adenosine, cardioversion, Valsalva, etc.)Valsalva, etc.)


Record a rhythm stripRecord a rhythm strip

ECG clues to diagnosisECG clues to diagnosis

Wide vs. narrow complexWide vs. narrow complex Regular vs. irregularRegular vs. irregular Abrupt vs. gradualAbrupt vs. gradual P wave relationship to QRSP wave relationship to QRS

Parade of RhythmsParade of Rhythms

Automatic ArrhythmiasAutomatic Arrhythmias

Automatic rhythms –Automatic rhythms –

Sinus TachycardiaSinus Tachycardia

Sinus node – fish-shaped structure Sinus node – fish-shaped structure with “head” at SVC-RA junction and with “head” at SVC-RA junction and “tail” extending along RA wall“tail” extending along RA wall

S-tach usually due to increased S-tach usually due to increased sympathetic discharge, fever, sympathetic discharge, fever, anemia, hypovolemia, anemia, hypovolemia, hyperthyroidism, etc.hyperthyroidism, etc.

Inappropriate sinus tachycardia - rareInappropriate sinus tachycardia - rare

Automatic rhythms – Automatic rhythms –

Sinus TachycardiaSinus Tachycardia

DxDx Rate greater than normal range, but Rate greater than normal range, but

usually less than 200usually less than 200 P wave axis normal (0 ~ +90P wave axis normal (0 ~ +90°°)) PR interval normalPR interval normal

TxTx Treat the causeTreat the cause


Automatic Atrial Automatic Atrial TachycardiaTachycardia

Originates from a focus in either the Originates from a focus in either the right or left atrium, or atrial septumright or left atrium, or atrial septum

Commonly from atrial appendages, Commonly from atrial appendages, crista terminalis, pulmonary veinscrista terminalis, pulmonary veins

Can also be due to central lines, etc.Can also be due to central lines, etc. Also called “ectopic atrial tachycardia”Also called “ectopic atrial tachycardia”

although any automatic rhythm other although any automatic rhythm other than sinus rhythm is technically “ectopic”than sinus rhythm is technically “ectopic”



DxDx Speeds-up and slows-down, rates varySpeeds-up and slows-down, rates vary P wave axis abnormalP wave axis abnormal PR interval may be abnormal (it is a PR interval may be abnormal (it is a

function of distance from focus to AVN)function of distance from focus to AVN) May see 2May see 2° AV block (e.g. Wenckebach ° AV block (e.g. Wenckebach

or 2:1 at higher atrial rates)or 2:1 at higher atrial rates) Adenosine Adenosine P waves “march through” P waves “march through”

despite AV blockdespite AV block





TxTx Remove source (check CXR and pull Remove source (check CXR and pull

back PICC)back PICC) Beta-blockersBeta-blockers

Esmolol infusion in ICU settingEsmolol infusion in ICU setting propranolol, atenololpropranolol, atenolol

Amiodarone, othersAmiodarone, others Catheter ablationCatheter ablation


Junctional TachycardiaJunctional Tachycardia

Originates from around the AV Originates from around the AV junctionjunction

Also called “JET” (Junctional Ectopic Also called “JET” (Junctional Ectopic Tachycardia), because it sounds coolTachycardia), because it sounds cool

Rate 170-200+Rate 170-200+ Most commonly seen post-Most commonly seen post-

operatively, usually self-limitedoperatively, usually self-limited Congenital forms, more persistentCongenital forms, more persistent



DxDx AV dissynchronyAV dissynchrony

Sinus P wave at different rate than narrow Sinus P wave at different rate than narrow QRSQRS

Atrial wire ECG (in post-op with pacing Atrial wire ECG (in post-op with pacing wires)wires)

““Cannon a-waves” on CVP monitorCannon a-waves” on CVP monitor Retrograde P waves (abnormal Pw axis)Retrograde P waves (abnormal Pw axis)

May be on top, before, or after QRSMay be on top, before, or after QRS



Cannon a-wavesCannon a-waves



TxTx Reduce catecholaminesReduce catecholamines

Decrease inotropic dripsDecrease inotropic drips Pain control and sedationPain control and sedation

Cooling/hypothermiaCooling/hypothermia Drugs (amiodarone)Drugs (amiodarone) ECMOECMO Catheter ablation(?)Catheter ablation(?)

Parade of RhythmsParade of Rhythms

Reentrant ArrhythmiasReentrant Arrhythmias

Reentrant rhythms – Reentrant rhythms –

Pathway Mediated Pathway Mediated TachycardiaTachycardia

Bypass tract of conductive tissue Bypass tract of conductive tissue connects atrium to ventricleconnects atrium to ventricle

Most common mechanism of SVT in Most common mechanism of SVT in childrenchildren

Rate 180-240Rate 180-240 May be “manifest” (e.g. WPW) or May be “manifest” (e.g. WPW) or

concealed (no preexcitation)concealed (no preexcitation) Pathway can be anywhere on mitral or Pathway can be anywhere on mitral or

tricuspid annuli, usually left-sidedtricuspid annuli, usually left-sided



Orthodromic reciprocating tachycardiaOrthodromic reciprocating tachycardia ““Runs correctly” with normal conductionRuns correctly” with normal conduction Down AV node (narrow QRS)Down AV node (narrow QRS) Up accessory pathway (retrograde)Up accessory pathway (retrograde) Retrograde P waves may be visible after QRSRetrograde P waves may be visible after QRS

Antidromic reciprocating tachycardiaAntidromic reciprocating tachycardia ““Runs against” normal conductionRuns against” normal conduction Down accessory pathway (wide QRS)Down accessory pathway (wide QRS) Up AV node (retrograde)Up AV node (retrograde) Less commonLess common



DxDx ElectrocardiogramElectrocardiogram Rhythm strips of start and stop of SVTRhythm strips of start and stop of SVT



TxTx Valsalva maneuvers, Ice to faceValsalva maneuvers, Ice to face Adenosine (technique matters!)Adenosine (technique matters!) Antiarrhythmic drugsAntiarrhythmic drugs

Beta blockers (watch blood glucose in Beta blockers (watch blood glucose in infants!)infants!)

Digoxin (limited value; digitalization only in Digoxin (limited value; digitalization only in difficult situations)difficult situations)

Others (Verapamil, Flecainide, Sotolol, etc.)Others (Verapamil, Flecainide, Sotolol, etc.) Catheter ablationCatheter ablation


Wolff-Parkinson-White Wolff-Parkinson-White SyndromeSyndrome

Electrocardiogram findingsElectrocardiogram findings Short PR intervalShort PR interval Wide QRS complexWide QRS complex Delta waveDelta wave





Clinical symptomsClinical symptoms PalpitationsPalpitations SVTSVT

Note narrow QRS and lack of delta wave!Note narrow QRS and lack of delta wave!



Sudden death(!)Sudden death(!) Atrial fibrillationAtrial fibrillation Rapid conduction over bypass tractRapid conduction over bypass tract Ventricular fibrillationVentricular fibrillation Risk 0.1-0.6% per yearRisk 0.1-0.6% per year



TxTx Tachycardia controlTachycardia control

RecognitionRecognition ±±Drugs (patient/family choice)Drugs (patient/family choice) Digoxin generally contraindicatedDigoxin generally contraindicated

Risk stratificationRisk stratification HolterHolter Exercise testingExercise testing Invasive electrophysiology testingInvasive electrophysiology testing

Catheter ablationCatheter ablation


AV Node Reentry AV Node Reentry TachycardiaTachycardia

More common in teens and adultsMore common in teens and adults Tachycardia circuit contained within Tachycardia circuit contained within

atrioventricular nodeatrioventricular node Activates atria at the “top” of the Activates atria at the “top” of the

circuit, ventricles at “bottom” of circuit, ventricles at “bottom” of circuit, nearly simultaneouslycircuit, nearly simultaneously

Rate 200-250Rate 200-250 Usually cannot see retrograde P Usually cannot see retrograde P

waveswaves





TxTx AdenosineAdenosine CardioversionCardioversion ±±PharmacotherapyPharmacotherapy

Beta blockersBeta blockers DigoxinDigoxin OthersOthers

Catheter ablationCatheter ablation


Atrial FlutterAtrial Flutter

““Flutter” circuit Flutter” circuit around anatomic around anatomic structures in structures in atriumatrium Eustachian valveEustachian valve Crista terminalisCrista terminalis Fossa ovalisFossa ovalis Surgical incisionsSurgical incisions



Atrial rate ~300 (higher in Atrial rate ~300 (higher in neonates)neonates)

Ventricular rate depends on AV Ventricular rate depends on AV node conductionnode conduction 1:1 1:1 300/min 300/min 2:1 2:1 150/min 150/min 3:1 3:1 100/min 100/min May be 3:1 then 2:1 then…May be 3:1 then 2:1 then…



Sawtooth “flutter” waves (may or Sawtooth “flutter” waves (may or may not be helpful)may not be helpful)



DxDx ElectrocardiogramElectrocardiogram Adenosine blocks AV node; flutter Adenosine blocks AV node; flutter

waves continuewaves continue TxTx

Rate control – digoxin, beta blockers, Rate control – digoxin, beta blockers, etc.etc.

Overdrive pacingOverdrive pacing DC cardioversionDC cardioversion Catheter ablationCatheter ablation

Threatening RhythmsThreatening Rhythms

Atrial fibrillation in high-risk WPWAtrial fibrillation in high-risk WPW Danger of ventricular fibrillationDanger of ventricular fibrillation

Persistent prolonged SVTPersistent prolonged SVT Tachycardia induced cardiomyopathy Tachycardia induced cardiomyopathy

(reversible)(reversible) SVT in compromised cardiac statusSVT in compromised cardiac status

Syncope or cardiovascular collapseSyncope or cardiovascular collapse

Treatment PearlsTreatment Pearls

AdenosineAdenosine

0.1-0.4 mg/kg/dose0.1-0.4 mg/kg/dose Very short half-life (seconds)Very short half-life (seconds) Central administration can be Central administration can be

helpful, but not necessaryhelpful, but not necessary RapidRapid saline bolus (5-10 ml) saline bolus (5-10 ml)

essentialessential Stopcock on venous access is Stopcock on venous access is

helpfulhelpful

DC CardioversionDC Cardioversion

DoseDose Cardioversion 0.25-1 J/kgCardioversion 0.25-1 J/kg Defibrillation 1-2 J/kgDefibrillation 1-2 J/kg

Synchronized (avoids making worse)Synchronized (avoids making worse) Paddles – front+apexPaddles – front+apex PatchesPatches

Front+apexFront+apex Front+backFront+back

Catheter AblationCatheter Ablation

Multiple cathetersMultiple catheters Size limitationsSize limitations

Ideally > 15 kg, but can be done in Ideally > 15 kg, but can be done in infants if necessaryinfants if necessary

Can be curativeCan be curative ~95% success rate in children~95% success rate in children

Record a Rhythm Strip!Record a Rhythm Strip!

Especially during interventionsEspecially during interventions Most SVT in infants and children is Most SVT in infants and children is

hemodynamically well-toleratedhemodynamically well-tolerated Proper diagnosis can guide Proper diagnosis can guide

appropriate therapyappropriate therapy RA/LA/RL/LL limb leads give 6 RA/LA/RL/LL limb leads give 6

electrograms (I, II, III, aVL, aVR, electrograms (I, II, III, aVL, aVR, aVF)aVF)

Documents

Supraventricular Tachycardia in Infancy and Childhood Terrence Chun, MD Pediatric Electrophysiology and Pacing