Management of postoperative arrhythmia

Chief, University of Nebraska and Creighton University Joint Division of Pediatric Cardiology,
D.B. and Paula Varner Professor of Pediatrics, University of Nebraska College of Medicine,
Director, Cardiology, Children's Hospital,
Omaha, Nebraska, USA
John D. Kugler

Postoperative（Po）arrhythmias（PoA）can be categorized temporally into early（EPoA）and late（LPoA）. EPoA, comprise the immediate Po period w 4-8 wks while LPoA comprise > 2 mo. EPoA occur in ≈25% of congenital heart disease surgery（CHDS）and are more common in pts with residual abnormal hemodynamics, infants and cyanotic CHDS. Most（≈65%）EPoA require some form of treatment and comprise brady/tachy PoA in Fontan-type CHDS, junctional ectopic tachycardia（JET）and AV block（AVB）. Bradycardia EPoA are managed by temporary or permanent atrial（a.）pacing. Intra-atrial reentry tachy（IART）, a. ectopic focus tachy（AET）and paroxysmal supraventricular tachycardia（PSVT）are managed by overdrive a. pacing, high rate bradycardia a. pacing and antiarrhythmia drugs（AD）. AD includes intravenous （IV）amiodarone（am）, procainamide（pa）, adenosine, or enteral flecainide（fl）, proprafenone（pr）. JET（≈1% of all CHDS; rate 160-300 bpm）diagnosis is by temporary a. wires（≈85% VA dissociation）. Transient AVB occurs in ≈20% JET. Risk factors for JET includes CHDS involving AV node/His bundle area, young age, small body size, fever, long cardio-pulmonary bypass time, intraoperative acidosis. JET therapy: body cooling（31-36°）, control endogenous and limit exogenous catecholamines, high rate bradycardia a. pacing, paired ventricular（v.）pacing, and AD（IV am; pa; enteral fl; pr）. AVB occurs in ≈3% of CHDS with highest incidence in left ventricular（LV）outflow tract obstruction and ventricular inversion（L-TGA）. Most pt（≈60%）with AVB regain AV conduction to avoid permanent pacing and, if so, it usually returns by day 9 Po. Thus, permanent pacing is warranted if AVB persists 9 d Po.
LPoA comprise an increasing problem for Po CHDS pts. With increased survival of complex CHDS and because of increased LPoA with Po time, increasing management challenges exist.
LPoA include sinus node dysfunction（SND）, IART, AET, AV node reentry tachy（AVNRT）, congenital and acquired accessory AV pathways/connections, late AV block and ventricular tachycardia（VT）. Fontan-type + Mustard/Senning comprise the largest group of pts with LPoA. IART, AET and SND are most common in this group but any Po pt with atriotomy provides the potential for “incisional” IART and these other a. LPoA. Acquired accessory AV pathway/connection can occur in pts with previous surgical atrio-pulmonary connection. Late AVB may occur mo-yr after CHDS in Down's syndrome pts. LPoA VT is usually macroreentry involving right v.（RV）outflow or v. septal defect（VSD）patch in tetralogy of Fallot-type CHDS with risk factors of older age at repair, residual abnormal hemodynamics causing large, dysfunctional RV, and wide QRS. A single management strategy for IART has not evolved. Technical progress（3-D mapping systems; better delivery of energy to produce full a. wall thickness scar）with radiofrequency catheter ablation（RFCA）provides promise（acute success ≈85%）but persistence of a. LPoA（recurrence of old + new IART, AET）remains a problem（≈40-75%）especially in the Fontan-type CHDS. Surgical approach（Maze-Cox III; a. pacemaker; Fontan revision to extracardiac）has revealed good results（≈5% recurrence; <2% mortality）to refractory IART. Non-RFCA/surgical management includes high rate（e.g. 80-100 bpm）a. pacing, AD（e.g. amiodarone, sotolol）, rate control AD（beta blocker; calcium blocker to avoid 1:1 AV conduction and sudden death）; overdrive a. pacing of permanent a. pacemaker, direct current cardioversion. LPoA VT is best managed by preventing progressive RV enlargement/dysfunction（surgical pulmonary or tricuspid valve replacement）. Detection of RV dysfunction appears best with periodic magnetic resonance imaging, cardio-pulmonary stress testing and monitoring of QRS duration. Successful RFCA of LPoA VT is achievable but remains overall disappointing. Implantation of cardio-defibrillator is warranted in high risk pts（e.g. documented VT and syncope）but specific indications to prevent SD in asymptomatic pts remain unknown until multi-center studies are conducted.