Source-sink Mismatch and Conduction Block: Simulation Study

Abstract Background Source-sink mismatch is one of the key concepts in arrhythmia mechanism such as relationship between pulmonary veins and the left atrium in atrial fibrillation. We sought to find the condition for conduction block in various geometries. Methods To simulate cardiac atrial tissue, the finite element method was used to discretize the governing equation in a 2D mesh. We evaluated under the following conditions: 6 sizes of source width (0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mm), 64 types of angle (θ) at the junction (30-330 degrees), 3 conditions of conduction velocity (CV) (x0.5, x0.75, and x1 of normal CV of atrial myocardium). Results Conduction block was not observed with source width > 0.5 mm in any settings. In reduced CV condition, conduction block was not observed in θ < 300 degrees when source width > 0.3 mm. The higher CV, conduction block was observed in the narrower θ. In cases of CV of x1.0 and x0.75, conduction block was observed in θ < 180 degrees when source width < 0.3 mm. The smaller source width, conduction block was observed in the narrower θ. The wider θ, the easier conduction block occurred. Conclusion Conditions for conduction block due to source-sink mismatch are as follows: smaller source width, higher CV, and wider θ. Source with width > 0.5 mm may not be associated with source-sink mismatch in the atrial tissue. CV slowing by antiarrhythmic drugs can be effective in the aspect of source-sink mismatch.