Validation of a new species for studying postoperative atrial fibrillation: Swine sterile pericarditis model.

Abstract

The canine sterile pericarditis model associated with atrial inflammation is an experimental counterpart of postoperative atrial fibrillation (POAF). However, the use of canines for research is restricted by ethics committees in many countries, and social acceptance is declining. To validate the feasibility of the swine sterile pericarditis model as an experimental counterpart to study POAF. Seven domestic pigs (35-60kg) underwent initial pericarditis surgery. On two or more postoperative days in the closed-chest state, we performed electrophysiological measurements of pacing threshold and atrial effective refractory period (AERP) while pacing from the right atrial appendage (RAA) and the posterior left atrium (PLA). The inducibility of POAF(>5min) by burst pacing was determined in both the conscious and anesthetized closed-chest state. These data were compared to previously published canine sterile pericarditis data for validation. The pacing threshold increased from day 1 to day 3 (2±0.1 to 3.3±0.6mA in the RAA, 2.5±0.1 to 4.8±0.2mA in the PLA). Also, the AERP increased from day 1 to day 3 (118±8 to 157±16ms in the RAA; 98±4 to 124±2ms in the PLA, both p<.05). Induction of sustained POAF occurred in 43% (POAF CL range 74-124ms). All electrophysiologic data from the swine model were consistent with the canine model with respect to (1) the range of both pacing threshold and AERP; (2) the progressive increase in threshold and AERP over time; (3) a 40%-50% incidence of POAF. A newly developed swine sterile pericarditis model demonstrated electrophysiologic properties consistent with the canine model and patients after open heart surgery.