Arrhythmias

• Prevalence of postoperative arrhythmia: 15-48%
• At risk: young age, low body weight, long CPB time, complex surgery, presence of residual defects
• Prevalence of postoperative arrhythmia is up to 50%
• Haemodynamic impairment in >50%
• Aggressive treatment in >50% required
• Most common is sinus bradycardia with/without junctional escape; then premature complexes; then supraventricular tachycardia; then AV block; then JET
• Mechanisms: re-entry: on/off, inducible, overdriveable, cardiovertable; automatic/ectopic: warm up, not inducible, not overdriveable, not cardiovertable

Prevention and unspecific treatment:

Strict maintenance of normothermia, avoid triggering drugs, avoid volume overload, avoid acidosis, Mg⁺⁺ >1.0, Ca⁺⁺ >1.0, K⁺ 4.5-5 mmol/L

Bradyarrhythmia

Sinus bradycardia causes: increased vagal tone, elevated ICP, drugs (digoxin, β-blocker, amiodarone, dexmedetomidine), respiratory (hypoxia), metabolic (hypoglycaemia, hyper/hypocalcaemia, hypomagnesiaemia), post-surgical (Fontan circulation, Mustard/Senning)

Sinus bradycardia treatment: correction of underlying cause, atropine 0.02 mg/kg, isoprenaline 0.1-2 mcg/kg/min infusion, pacing (AAI, DDD, DDI)

AV block causes: congenital, increased vagal tone, drugs, respiratory, metabolic, post-surgical (VSD, AVSD, ccTGA, TGA, Fontan circulation)

AV block treatment: correction of underlying cause, pacing (VVI, DDD, DDI)

Tachyarrhythmia

Sinus tachycardia causes: central (pain, awake, fever, seizure), cardiovascular (hypovolaemia, LCOS, pulmonary hypertension), respiratory (hypoxia, hypercarbia), heart failure

Sinus tachycardia treatment: correction of underlying cause, sedation, fluid bolus, general prevention and treatment

Intraatrial reentry tachycardia (IART ≈ atypical atrial flutter) causes: post-surgical (Fontan circulation, Mustard/Senning, ccTGA, TOF, Ebstein's anomaly, VSD, ASD, TGA)

Intraatrial reentry tachycardia treatment: adenosine (100 mcg/kg IV, increasing up to 300 mcg/kg); overdrive pacing if rate low enough; cardioversion (1 J/kg); amiodarone (loading 25 mcg/kg/hr for 4 hours followed by 5-15 mcg/kg/min infusion for rate control or digoxin (20 mcg/kg IV in infants, 30-40 mcg/kg in children). Titrate for effect. AV reciprocating tachycardia (WPW if preexcitation on baseline ECG).

Atrial ectopic tachycardia (AET ≈ chaotic atrial tachycardia): difficult to control pharmacologically –

• β -blocker: esmolol (bolus up to 500 mcg/kg IV followed by 100-1000 mcg/kg/min infusion) or propranolol (bolus 10-100 mcg/kg slowly IV)
• Digoxin, procainamide, flecainide (3-6 mg/kg/day), sotalol (2-6 mg/kd/day), amiodarone
• Overdrive-pacing if rate low enough
• Catheter ablation
• Consider sedation if compromised cardiac output

Atrial fibrillation causes: preexcitation syndromes, post-surgical (ASD, Fontan circulation, AS)

Atrial fibrillation treatment: amiodarone, overdrive pacing, cardioversion (1 J/kg). Consider anticoagulation if persistent >48 hrs

Junctional ectopic tachycardia (JET) (180-250 bpm) causes: congenital, post-surgical (ASD, VSD, AVSD, TOF, Fontan circulation)

Junctional ectopic tachycardia (JET)  treatment: decrease adrenergic drugs if feasible, electrolyte correction (Mg⁺⁺and K⁺), sedation and paralysis, overdrive pacing, amiodarone, surface cooling to 35°C to slow heart rate (and allow AV sequential pacing)

Premature ventricular contraction (PVC): < 1/min acceptable, otherwise – treatment of underlying cause. Beta-blocker if clinically indicated.

Ventricular tachycardia causes: respiratory, metabolic (inborn errors of metabolism), drugs (Class I, Class III, digitalis toxicity), anatomical (myocarditis), post-surgical, idiopathic.

Ventricular tachycardia treatment: in anunstable patient – immediate cardioversion (1-4 J/kg) and CPR; correction of underlying cause; amiodarone (loading over 20 mins at 5 mg/kg IV) or procainamide (loading over 30 mins: 10 mg/kg IV), catheter ablation, ICD .

Torsade de pointes (polymorph VT) causes: TCA intoxication, long QT Syndrome, dyselectrolytaemia, see also VT

Torsade de pointes treatment: MgSO4 (0.2 mmol/kg), consider beta-blocker or pacing if recurrent.

Ventricular fibrillation: immediate DC and CPR – resuscitation.

References:

[1] Critical Heart Disease in Infants and Children; 2nd ed, Nichols et al: Arrhythmia

[2] Am J Emerg Med. 2008 Mar;26(3):348-58: O'Connor et al: The pediatric electrocardiogram part II: Dysrhythmias

[3] Anaesth Intensive Care. 2009 Sep;37(5):705-19: Skippen et al: Diagnosis of postoperative arrhythmias following paediatric cardiac surgery

[4] Nat Clin Pract Cardiovasc Med. 2008 Aug;5(8):469-76. Snyder: Postoperative ventricular tachycardia in patients with congenital heart disease: diagnosis and management

[5] Pacing Clin Electrophysiol. 2008 Feb;31 Suppl 1:S2-6: Roos-Hesselink et al: Significance of postoperative arrhythmias in congenital heart disease

[6] Circulation. 2007 Jun 26;115(25):3224-34: Walsh: Interventional electrophysiology in patients with congenital heart disease

[7] Circulation. 2007 Jan 30;115(4):534-45: Walsh et al: Arrhythmias in adult patients with congenital heart disease

[8] Z Kardiol. 2004 May;93(5):371-80: Haas et al: Postoperative junctional ectopic tachycardia (JET)

[9] Circ Arrhythm Electrophysiol. 2010 Apr 1;3(2):134-40: Chang et al: Amiodarone versus procainamide for the acute treatment of recurrent supraventricular tachycardia in pediatric patients

[10] Pediatr Emerg Care. 2007 Mar;23(3):176-85; Manole MD: Emergency department management of the pediatric patient with supraventricular tachycardia

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