Arrhythmias Post Tetralogy of Fallot Surgical Repair
Joseph Atallah, MD CM, SMDivision of Pediatric Cardiology
Section of Electrophysiology
Outline
• 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
.
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
– 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
PQRS
?T PQRS
P PQRS
2 1
Heart Block
P P P
QRS
Heart Block
Narrow QRSWide 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 TachycardiaV V V V VA A A AVA
Treatment
SLOW
• Weaning sedation• Warming up• Medications– Atropine– Isoproterenol– Epinephrine
• Pacing– Atrial, ventricular or both
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
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