Abstract 11973: Newly Created Animal Model of Human Post-Operative Junctional Ectopic Tachycardia
Introduction: Junctional ectopic tachycardia (JET) complicates the post-operative (PO) recovery from open heart surgery (OHS) in children (5-15% incidence). JET risk factors include younger age, and prolonged cardiopulmonary bypass times (CPB). PO JET occurs 1) early after OHS, 2) in the setting of PO sinus node (SN) dysfunction and 3) exhibits a QRS morphology consistent with origin from the His bundle (JET) or proximal conduction fascicles (fascicular tachycardia (FT)). Our goal was to develop an animal model for PO JET to understand the mechanisms for PO JET and improve management.
Methods and Results: Eleven swine animals aged 3-6 months underwent OHS to assess the necessary elements for development of PO JET under general anesthesia (1-3% isoflurane supplemented with midazolam and sufentanil). Atrial and ventricular pacing and recording electrodes where sewn to the left atrium and right ventricle after sternotomy. SN dysfunction was attempted using clamp crushing or radiofrequency ablation (successful in 1 of 4 attempts), or SN removal (success 5 of 5 attempts). Prolonged CPB (> 120 minutes) was instituted with and without isoproterenol infusion (no spontaneous JET). PO junctional or FT could be initiated either following slow AV nodal pathway ablation (during CPB) and/or digoxin administration (96 ± 54 mcg/kg). JET occurred in 7/9 animals (mean ventricular rate = 173 ± 34 bpm) and FT occurred in 9/9 animals (mean ventricular rate = 187 ± 39 bpm). His and right bundle recordings confirmed conduction system (CS) origin of the arrhythmia (arrows in figure). Two animals died early from malignant hyperthermia.
Conclusions: Experimental PO JET or FT can occur in the intra-operative setting of SN dysfunction, prolonged CPB and enhanced automaticity of the His-Purkinje CS. CS automaticity followed physical injury, cardiac ischemia or sodium-potassium ATPase inhibition. This animal model will serve as the basis to assess new interventions for treatment of PO JET and FT.
- Congenital heart disease
- Pediatric electrophysiology
- Cardiac surgery
- Supraventricular tachycardia
- Atrioventricular node
- © 2011 by American Heart Association, Inc.