Arrhythmias Post Tetralogy of
Fallot Surgical Repair
Joseph Atallah, MD CM, SM
Division of Pediatric Cardiology
Section of Electrophysiology
Outline
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Why is there a risk of arrhythmias
Arrhythmia classification
Recognition
Treatment
Longterm outcomes
Summary
Arrhythmias … Why?
Arrhythmias … Why?
• Incidence
– 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
Arrhythmia Classification
• SLOW
• FAST
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Arrhythmia Classification
• SLOW
– Sinus bradycardia
– Heart block
• FAST
– Sinus tachycardia
– Atrial tachycardia
– Supraventricular tachycardia
– Junctional tachycardia
– Ventricular tachycardia
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 10-20-30 years post-op
Definition and Recognition
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
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LVOTO surgery
VSD Closure
TOF
ccTGA
• Definition: more P waves than QRS complexes (more As than Vs)
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
Heart Block
QRS
P ?T
QRS
P P
QRS
P
2 1
Heart Block
QRS
P
P
P
Heart Block
Narrow QRS
Wide QRS
Heart Block
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
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
Junctional Tachycardia
QRS
P
V
A
V
A
V
V
A
Junctional Tachycardia
Junctional Tachycardia
AV
V A V A V AV
VA
Treatment
SLOW
• Weaning sedation
• Warming up
• Medications
– Atropine
– Isoproterenol
– Epinephrine
• Pacing
– Atrial, ventricular or both
FAST
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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
Outcomes
Long-term Outcomes
• Heart Block
– 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
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