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Supraventricular Tachycardia in Infancy and Childhood

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Presentation on theme: "Supraventricular Tachycardia in Infancy and Childhood"— Presentation transcript:

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

2 Cardiac electrical anatomy

3 SVT - Overview Rapid rhythm that involves or is driven by structures in the upper heart Incidence up to 1:250 children Generally well-tolerated, even fast rates Risk of life-threatening arrhythmias is uncommon

4 Narrow vs. Wide QRS Not all narrow QRS complex tachycardia is supraventricular tachycardia Not all wide QRS complex tachycardia is ventricular tachycardia

5 SVT Mechanisms - Overview
Reentrant rhythms Automatic rhythms

6 SVT mechanisms – Automatic Rhythms
Originate from a particular focus “Warm-up” and “cool-down” behavior Respond to drugs and maneuvers that affect myocardial automaticity May be suppressed by faster rates Usually do not respond to cardioversion (typically pause, then restart)

7 SVT mechanisms – Automatic Rhythms
Left atrial focus 2:1 AVN conduction

8 SVT mechanisms – Reentrant rhythms
Requires a “circuit” of tissue to create repetitive activation Must have appropriate conditions to perpetuate reentrant rhythm Usually abrupt onset and termination Regular, with little variation in rate Often will respond to cardioversion

9 SVT mechanisms – Reentrant rhythms

10 Diagnostic methods 12-lead electrocardiogram ! ! !
Post-op atrial/ventricular pacing wires Esophageal pacing leads Adenosine can be diagnostic Invasive electrophysiology study

11 Diagnostic methods Always
Always record a rhythm strip during any intervention (adenosine, cardioversion, Valsalva, etc.)

12 Diagnostic methods Record a rhythm strip

13 ECG clues to diagnosis Wide vs. narrow complex Regular vs. irregular
Abrupt vs. gradual P wave relationship to QRS

14 Parade of Rhythms Automatic Arrhythmias

15 Automatic rhythms – Sinus Tachycardia
Sinus node – fish-shaped structure with “head” at SVC-RA junction and “tail” extending along RA wall S-tach usually due to increased sympathetic discharge, fever, anemia, hypovolemia, hyperthyroidism, etc. Inappropriate sinus tachycardia - rare

16 Automatic rhythms – Sinus Tachycardia
Dx Rate greater than normal range, but usually less than 200 P wave axis normal (0 ~ +90°) PR interval normal Tx Treat the cause

17 Automatic rhythms – Automatic Atrial Tachycardia
Originates from a focus in either the right or left atrium, or atrial septum Commonly from atrial appendages, crista terminalis, pulmonary veins Can also be due to central lines, etc. Also called “ectopic atrial tachycardia” although any automatic rhythm other than sinus rhythm is technically “ectopic”

18 Automatic rhythms – Automatic Atrial Tachycardia
Dx Speeds-up and slows-down, rates vary P wave axis abnormal PR interval may be abnormal (it is a function of distance from focus to AVN) May see 2° AV block (e.g. Wenckebach or 2:1 at higher atrial rates) Adenosine  P waves “march through” despite AV block

19 Automatic rhythms – Automatic Atrial Tachycardia

20 Automatic rhythms – Automatic Atrial Tachycardia
Tx Remove source (check CXR and pull back PICC) Beta-blockers Esmolol infusion in ICU setting propranolol, atenolol Amiodarone, others Catheter ablation

21 Automatic rhythms – Junctional Tachycardia
Originates from around the AV junction Also called “JET” (Junctional Ectopic Tachycardia), because it sounds cool Rate Most commonly seen post-operatively, usually self-limited Congenital forms, more persistent

22 Automatic rhythms – Junctional Tachycardia
Dx AV dissynchrony Sinus P wave at different rate than narrow QRS Atrial wire ECG (in post-op with pacing wires) “Cannon a-waves” on CVP monitor Retrograde P waves (abnormal Pw axis) May be on top, before, or after QRS

23 Automatic rhythms – Junctional Tachycardia
Cannon a-waves

24 Automatic rhythms – Junctional Tachycardia
Tx Reduce catecholamines Decrease inotropic drips Pain control and sedation Cooling/hypothermia Drugs (amiodarone) ECMO Catheter ablation(?)

25 Parade of Rhythms Reentrant Arrhythmias

26 Reentrant rhythms – Pathway Mediated Tachycardia
Bypass tract of conductive tissue connects atrium to ventricle Most common mechanism of SVT in children Rate May be “manifest” (e.g. WPW) or concealed (no preexcitation) Pathway can be anywhere on mitral or tricuspid annuli, usually left-sided

27 Reentrant rhythms – Pathway Mediated Tachycardia
Orthodromic reciprocating tachycardia “Runs correctly” with normal conduction Down AV node (narrow QRS) Up accessory pathway (retrograde) Retrograde P waves may be visible after QRS Antidromic reciprocating tachycardia “Runs against” normal conduction Down accessory pathway (wide QRS) Up AV node (retrograde) Less common

28 Reentrant rhythms – Pathway Mediated Tachycardia
Dx Electrocardiogram Rhythm strips of start and stop of SVT

29 Reentrant rhythms – Pathway Mediated Tachycardia
Tx Valsalva maneuvers, Ice to face Adenosine (technique matters!) Antiarrhythmic drugs Beta blockers (watch blood glucose in infants!) Digoxin (limited value; digitalization only in difficult situations) Others (Verapamil, Flecainide, Sotolol, etc.) Catheter ablation

30 Reentrant rhythms – Wolff-Parkinson-White Syndrome
Electrocardiogram findings Short PR interval Wide QRS complex Delta wave

31 Reentrant rhythms – Wolff-Parkinson-White Syndrome

32 Reentrant rhythms – Wolff-Parkinson-White Syndrome
Clinical symptoms Palpitations SVT Note narrow QRS and lack of delta wave!

33 Reentrant rhythms – Wolff-Parkinson-White Syndrome
Sudden death(!) Atrial fibrillation Rapid conduction over bypass tract Ventricular fibrillation Risk % per year

34 Reentrant rhythms – Wolff-Parkinson-White Syndrome
Tx Tachycardia control Recognition ±Drugs (patient/family choice) Digoxin generally contraindicated Risk stratification Holter Exercise testing Invasive electrophysiology testing Catheter ablation

35 Reentrant rhythms – AV Node Reentry Tachycardia
More common in teens and adults Tachycardia circuit contained within atrioventricular node Activates atria at the “top” of the circuit, ventricles at “bottom” of circuit, nearly simultaneously Rate Usually cannot see retrograde P waves

36 Reentrant rhythms – AV Node Reentry Tachycardia

37 Reentrant rhythms – AV Node Reentry Tachycardia
Tx Adenosine Cardioversion ±Pharmacotherapy Beta blockers Digoxin Others Catheter ablation

38 Reentrant rhythms – Atrial Flutter
“Flutter” circuit around anatomic structures in atrium Eustachian valve Crista terminalis Fossa ovalis Surgical incisions

39 Reentrant rhythms – Atrial Flutter
Atrial rate ~300 (higher in neonates) Ventricular rate depends on AV node conduction 1:1  300/min 2:1  150/min 3:1  100/min May be 3:1 then 2:1 then…

40 Reentrant rhythms – Atrial Flutter
Sawtooth “flutter” waves (may or may not be helpful)

41 Reentrant rhythms – Atrial Flutter
Dx Electrocardiogram Adenosine blocks AV node; flutter waves continue Tx Rate control – digoxin, beta blockers, etc. Overdrive pacing DC cardioversion Catheter ablation

42 Threatening Rhythms Atrial fibrillation in high-risk WPW
Danger of ventricular fibrillation Persistent prolonged SVT Tachycardia induced cardiomyopathy (reversible) SVT in compromised cardiac status Syncope or cardiovascular collapse

43 Treatment Pearls

44 Adenosine 0.1-0.4 mg/kg/dose Very short half-life (seconds)
Central administration can be helpful, but not necessary Rapid saline bolus (5-10 ml) essential Stopcock on venous access is helpful

45 DC Cardioversion Dose Synchronized (avoids making worse)
Cardioversion J/kg Defibrillation 1-2 J/kg Synchronized (avoids making worse) Paddles – front+apex Patches Front+apex Front+back

46 Catheter Ablation Multiple catheters Size limitations Can be curative
Ideally > 15 kg, but can be done in infants if necessary Can be curative ~95% success rate in children

47 Record a Rhythm Strip! Especially during interventions
Most SVT in infants and children is hemodynamically well-tolerated Proper diagnosis can guide appropriate therapy RA/LA/RL/LL limb leads give 6 electrograms (I, II, III, aVL, aVR, aVF)

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