Electrophysiological models for the heterogeneous canine atria: computational platform for studying rapid atrial arrhythmias

Abstract

Heterogeneity in the electrical action potential (AP) properties can provide a substrate for atrial arrhythmias, especially at rapid pacing rates. In order to quantify such substrates, we develop a family of detailed AP models for canine atrial cells. An existing model for the canine right atrial (RA) myocyte was modified based on electrophysiological data from dog to create new models for the canine left atrium (LA), the interatrial Bachmann's bundle (BB), and the pulmonary vein (PV). The heterogeneous AP models were incorporated into a tissue strand model to simulate the AP propagation, and used to quantify conditions for conduction abnormalities (primarily, conduction block at rapid pacing rated) in the canine atria.

Fig. 1

Ionic channel and AP heterogeneity between the RA and LA. Top: Differences in the current-voltage relationships for I_Kr between the atria. Bottom: Resultant AP differences between the RA and LA models. Model simulations match the experimental recordings [8].

Fig. 2

Ionic channel and AP heterogeneity between the RA and BB. Top: Differences in the mean ionic current densities between the RA (closed bars) and BB (open bars) in rabbit [13]. Middle: Respective differences introduced between the canine RA and BB cell models. Bottom: Resultant AP differences between the RA and BB models. AP morphology matches the respective experimental recordings [15].

Fig. 3

Ionic channel and AP heterogeneity between the LA and PV. Top: Differences in the mean ionic channel current densities [9] used between the canine LA (closed bars) and PV (open bars) cell models. Bottom: Resultant AP differences between the LA and PV models.

Fig. 4

Slowing and block of AP conduction between the RA and BB regions of 1D tissue strand. Top: Schematic illustration of the 10 mm strand comprising of the RA cells (0-5 mm) and BB cells (5-10 mm). Arrow shows the direction of AP propagation. APs are recorded from the middle of the RA region, the middle of the BB region and the RA-BB junction (JT). Middle: Slowing of the AP conduction can be seen as the increased time delay between APs from the JT and the BB regions. Bottom: Block of the AP conduction through the BB region.