Advanced Development in Arrhythmia Mechanisms and Therapy

Characterization of the complexity of atrial fibrosis in a persistent atrial fibrillation swine model

The goals of this study are to assess the types of arrangement of collagen fibers with the two-photon microscope and second harmonic generation techniques. Then, apply mathematical procedures (2-dimension Fourier transformation) to understand the spatial disarray of collagen fibers in the atria. Furthermore, compare these results with tissue total collagen levels and peripheral and central plasma soluble collagen levels.

To achieve these goals, we have chosen the following methodology and procedures:

• The chosen model is pig. Pigs are implanted with pacemakers for fast atrial pacing and induce an state of persistent atrial fibrillation (AF). The ventricles are protected of the effects of AF by and AV node ablation.
• The areas selected for the study are as follows: left atria (LA), right atria (RA), posterior left atria (PLA), right ventricle (RV) and left ventricle (LV).
• The tissue will be formalin-fixed and paraffin-embedded. The tissue will be then cut into 5 µm slides. Half of the slices will be devoted to H&E staining to check if the tissue has any abnormalities. The other half will not be stained. They will be deparaffinized and rehydrated. They will be mounted with a coverslip. These are the samples for the two-photon microscope and SHG.
• Some of the remaining tissue will be used to quantify total collagen levels with a commercial kit which is yet to be determined.
• Peripheral and central blood will be used to measure soluble collagen and LOX levels.