Morphometric analysis of cardiac conduction fibers in horses and dogs, a comparative histological and immunohistochemical study with findings in human hearts.

The researchers conducted a comparative study on the morphological characteristics of cardiac conduction cells in horse and dog hearts and found significant differences in cell density, thickness, area, and diameter, and in the number of junctions. This new information contributes to the understanding of cardiac conduction fibers, potentially helping in the prevention and treatment of ventricular arrhythmias.

Research Purpose and Method

• The researchers aimed to conduct a detailed morphometric study on the morphological parameters that characterize cardiac conduction cells, which are crucial for the rapid electrical activation of the ventricles. This information can help distinguish such cells from other types of cells.
• The study used five hearts each from male horses and male dogs. These hearts were processed with a 5% formaldehyde solution to prepare them for investigation.
• Histological sections of 5 μm thickness were procured and stained with hematoxylin-eosin and Masson’s trichrome to highlight the microscopic structures of the tissues. Desmin, connexin 40, and a PAS method were used to identify cardiac conduction cells and their junctions.

Key Findings

• Comparing the density and thickness of the cardiac conduction fibers, significant differences were found. The density and thickness of these fibers were much higher in horses than in dogs.
• When investigating the area and diameters of the cardiac conduction cells, they were found to be greater in horses than in dogs. This was a significant difference.
• The study found that dogs have more junctions (30.8%) in their cardiac conduction fibers than horses (26.1%). This difference was statistically significant.

Conclusion and Impact

• The research provides new knowledge on the cardiac conduction fibers’ distribution in different animal species, contributing valuable data to the morphological study of the cardiac conduction system.
• The ability to locate the site with the highest density of cardiac conduction fibers may contribute to cardiological studies.
• These findings could help prevent ventricular arrhythmias and identify suitable areas for treatment. Ventricular arrhythmias are disorders of heart rhythm that originate in the heart’s lower chambers and can be life-threatening, making this research findings valuable.