Histomorphometry and Stereological Study of Septomarginal Trabecula in Pig’s Heart

Introduction: cardiovascular disease is one of the main causes of morbidity and mortality worldwide. Important knowledge about the cardiovascular system was acquired through the use of experimental research and requires choosing a suitable model. The similarities in anatomy and physiology between pigs and humans, swine have emerged as a model for preclinical protocols. The septomarginal trabecula (ST) is an extremely important fibromuscular structure located in the right ventricle of most species. Variations in the ST anatomical and histological structures has a significant cardiac physiology and clinical importance. The purpose of this study was to perform morphometry and stereology analyzes of the ST in right ventricles of pig's hearts. Material and Methods: fourteen pig hearts were analyzed macroscopically to obtain an anatomical description and length and thickness measurements. For histological and stereological analysis were also performed. Results: the swine hearts presented the ST as a tubular fibromuscular band with significant variation in length and diameter. Variations were also observed in the number of fixations (single, bifurcated, quadrifurcated). The volume density of the tissues present in the ST showed the predominance of cardiac muscle tissue followed by connective tissue. The stereological analyzes showed also significant differences in the amount of cardiac muscle and connective tissue in thin and thick structures. Conductive fibers were surrounded by the connective tissue and, were more peripherally located in the thick ST compared to the thin ST. Conclusion: in pig hearts, morphological and histological variations found in ST suggest possible correlations with changes in cardiac physiology.