Post operative cardiac arrhythmias

Post operative cardiac arrhythmias

Postoperative cardiac arrhythmias are a major cause of morbidity and mortality, more so following surgery for congenital heart disease. Tolerability of arrhythmia is less in the postoperative period than for similar arrhythmia in the preoperative period. Hemodynamic instability is more likely due to the possibility of myocardial dysfunction. Cardiopulmonary bypass, injury to the conduction system during surgery, metabolic and electrolyte abnormalities, especially hypokalemia and hypomagnesemia contribute to the increased incidence of postoperative arrhythmias. Stress of the surgery with enhanced sympathetic tone and use of inotropic support are added factors. Delayed arrhythmia can occur due to scar related re-entry. Atrial fibrillation is one of the commonest arrhythmias after coronary artery bypass surgery. Perioperative use of beta blockers have a role in reducing the incidence of postoperative atrial fibrillation. The earlier you resume beta blockers after surgery the better. A note of caution about beta blockers is needed in those with bradycardia and ventricular dysfunction.
Junctional ectopic tachycardia (JET) is a unique postoperative arrhythmia, especially in children after cardiac surgery. JET is often difficult to treat. It is likely to recur after cardioversion. Sedation and cooling (hypothermia) are helpful.
It is always better to take a 12 lead ECG for evaluation of postoperative cardiac arrhythmia rather than taking a decision from the monitor tracing, except in a dire emergency. If P waves are not seen well on surface ECG, an electrogram from the atrial pacing wire is useful.
Synchronized cardioversion is to be used for any tachycardia with a well formed QRS. Overdrive pacing is useful in re-entrant tachycardia. DC shock is also useful in re-entry. There is no point in giving a DC shock for tachycardia due to enhanced automaticity like JET – it will recur soon.
Postoperative complete heart block (CHB)
Edema in the region of the conduction system may contribute to CHB. May wait 10-15 days prior to permanent pacemaker implantation. Steroids have been tried to treat CHB due to inflammatory edema.
Prophylactic treatment for prevention of postoperative atrial fibrillation
While drugs like sotalol and amiodarone have been used, evidence is more in favour of beta blockers in preventing postoperative atrial fibrillation.