Specialized conduction cells aggregated in a distinct structure surrounded by fibro-fatty tissue were identified in the fossa ovalis and its flap valve in 95% of human interatrial septum specimens.
Observational (n=46)
No
This study provides histological and ultrastructural evidence of specialized conduction cells in the human interatrial septum, which may have implications for the pathophysiology of atrial fibrillation.
BACKGROUND: There is a paucity of information on structural organization of muscular bundles in the interatrial septum (IAS). The aim was to investigate histologic and ultrastructural organization of muscular bundles in human IAS, including fossa ovalis (FO) and flap valve. METHODS: Macroscopic and light microscopy evaluations of IAS were performed from postmortem studies of 40 patients. Twenty three IAS specimens underwent serial transverse sectioning, and 17--longitudinal sectioning. The transverse sections from 10 patients were immunolabeled for HCN4, Caveolin3 and Connexin43. IAS specimens from 6 other patients underwent electron microscopy. RESULTS: In all IAS specimens sections the FO, its rims and the flap valve had muscle fibers consisting of working cardiac myocytes. Besides the typical cardiomyocytes there were unusual cells: tortuous and horseshoe-shaped intertangled myocytes, small and large rounded myocytes with pale cytoplasm. The cells were aggregated in a definite structure in 38 (95%) cases, which was surrounded by fibro-fatty tissue. The height of the structure on transverse sections positively correlated with age (P = 0.03) and AF history (P = 0.045). Immunohistochemistry showed positive staining of the cells for HCN4 and Caveolin3. Electron microscopy identified cells with characteristics similar to electrical conduction cells. CONCLUSIONS: Specialized conduction cells in human IAS have been identified, specifically in the FO and its flap valve. The cells are aggregated in a structure, which is surrounded by fibrous and fatty tissue. Further investigations are warranted to explore electrophysiological characteristics of this structure.
Митрофанова et al. (Thu,) conducted a observational in Postmortem human hearts (n=46). Histological and ultrastructural evaluation was evaluated on Identification of specialized conduction cells in human interatrial septum. Specialized conduction cells aggregated in a distinct structure surrounded by fibro-fatty tissue were identified in the fossa ovalis and its flap valve in 95% of human interatrial septum specimens.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: