Effect of trabecular structure on impulse propagation in a 1-cm × 1-cm slab of atrial tissue. A planar depolarization wave was generated by stimulating the left side of the tissue slab. Overall stretch ratio was 1:2. Top: photographic picture of atrial tissue from rabbit [Eijsbouts et al 2003]; thickness as computed from the brightness of the picture; stretch ratio just before electrical stimulation. Bottom: conduction velocity; maximum upstroke velocity (dVmem/dt)max; action potential duration (APD at -60mV). The higher conduction velocity and (dVmem/dt)max on the right is a boundary effect.

Figure 2 from:
Mechano-Electrical Coupling Influences Onset and Perpetuation of Atrial Fibrillation during Acute Atrial Dilatation
Nico H. L. Kuijpers, Mark Potse, Peter M. van Dam, Huub M. M. ten Eikelder, Sander Verheule, Frits W. Prinzen, and Ulrich Schotten
Heart Rhythm 8:429-436, 2011