1. Arrhythmias Post Tetralogy of Fallot Surgical Repair
Joseph Atallah, MD CM, SM
Division of Pediatric Cardiology
Section of Electrophysiology

2. Outline Why is there a risk of arrhythmias Arrhythmia classification
Recognition
Treatment
Longterm outcomes
Summary

3. Arrhythmias … Why?

4. Arrhythmias … Why? Incidence Risk factors
Up to 36% of post-op TOF patients will experience some arrhythmic event, mostly insignificant and brief
Majority resolve within 48 hrs post-op
Risk factors
Young age at surgery
Longer bypass and aortic cross-clamp time
Complexity of repair

5. Arrhythmia Classification
SLOW
FAST .

6. Arrhythmia Classification
SLOW
Sinus bradycardia
Heart block
FAST
Sinus tachycardia
Atrial tachycardia
Supraventricular tachycardia
Junctional tachycardia
Ventricular tachycardia

7. Arrhythmia Classification
SLOW
Sinus bradycardia
Intrinsic: sinus node dysfunction (rare)
Extrinsic: medications (sedation …), increased ICP …
Heart block
Results from damage to the AVN, His bundle or bundle branches
FAST
Sinus tachycardia
Common: medications (inotropes, sedation …), hemodynamic stress …
Atrial tachycardia
Rare
Supraventricular tachycardia
ORT or AVNRT or atrial flutter
Junctional tachycardia
Relatively common: multifactorial
Ventricular tachycardia
Rare, more of an issue years post-op

8. Definition and Recognition

9. Heart Block SLOW Heart block
Incidence is 1-3% of all pediatric open heart surgeries
Often recognized in the operating room
However, may be acute or gradual in onset in first few days post-op
Highest risk surgeries
LVOTO surgery
VSD Closure
TOF
ccTGA
Definition: more P waves than QRS complexes (more As than Vs)

10. Heart Block SLOW Heart block 2nd degree (partial)
Not every atrial beat is conducted to the ventricle = ventricular rate is slower than the atrial rate (2:1, 3:1 …)
3rd degree (complete)
No (zero) atrial beat is conducted to the ventricle
Extreme: HR (VR) = 0 … flat line … bad news … please help!
Most common: ventricular escape rhythm at a certain rate
Inadequate slow vs. acceptable rate
Narrow vs. wide complex QRS

11. Heart Block
QRS
QRS
QRS P ?T P P P 2 1

12. Heart Block
QRS P P P

13. Heart Block
Narrow QRS
Wide QRS

14. Heart Block

15. Arrhythmia Recognition
FAST
Supraventricular Tachycardia
Usual rate between 180 and 280 bpm
Sudden onset and termination
Minimal HR variation during SVT
Junctional Tachycardia
Usual rate between 160 and 230 bpm
Gradual onset and termination
HR variation during JET

16. Junctional Tachycardia
Onset within the first 24 hrs post-op
Due to stress injury around the AV node and the His bundle
Inappropriate accelerated rhythm with the same QRS morphology as sinus rhythm
Often with more Vs then As = VA dissociation
Most common after TOF repair

17. Junctional Tachycardia
QRS V V V V P A A A

18. Junctional Tachycardia

19. Junctional TachycardiaV V A V A V A V V A

20. Treatment

21. SLOW Weaning sedation Warming up Medications Pacing Atropine
Isoproterenol
Epinephrine
Pacing
Atrial, ventricular or both

22. FAST Optimize hemodynamics
Correcting electrolyte and acid-base disturbances
Weaning certain inotropes (e.g. Epi, Dexmetomedine)
Optimizing sedation
Cooling
Anti-arrhythmic drugs
Procainamide
Amiodarone
Esmolol
Overdrive atrial pacing

23. Outcomes

24. Long-term Outcomes Heart Block Supraventricular tachycardia
At least 60% resolve in the first month post-op
~90% of those will occur in the first 10 days post-op
Remaining require a permanent pacemaker implantation despite the possibility of late recovery of AV conduction
Supraventricular tachycardia
May resolve
Medical therapy or ablation
Junctional tachycardia
May be very resilient and life threatening
Usually resolves within 2 days but may last 8 days

25. Summary Most common arrhythmias post surgical repair of TOF
Heart block
Junctional tachycardia
A simple analytical approach to recognition
Multiple treatment options, ultimately:
Pacing for heart block
AAD for junctional tachycardia
Long-term outcomes:
Heart block: 30-40% will require pacing
ST and JT usually resolve early on