Resumo

LAZA, Sebastián et al. Bases anatómicas de la fibrilación atrial: Estudio descriptivo de la extensión de músculo cardiaco atrial hacia la vena cava superior.. Rev.Urug.Cardiol. [online]. 2005, vol.20, n.2, pp.69-76. ISSN 1688-0420.

SUMMARY Introduction: Atrial fibrillation can be triggered from myocardial sleeves present in superior vena cava coming from the right atrium. Purpose: Anatomic and histologic description of myocardial sleeves, main relationships and clinical implications for catheter ablation. Methods: Fourty-three human hearts were examined by dissection and histological analysis. Superior cavoatrial junction and presence, extension, disposition, distribution and maximum highness of myocardial sleeves in SVC were studied by quadrants. Results: All studied specimens showed myocardial extensions from right atrium to SVC. Myocardial breakthroughs (MB) were studied in 19 cases. 2 MB were found in 63%, 3 in 15,8% and 4 in 10,5% of the cases, coming from the high lateral right atrium and right atrial appendage, and located by frequency in the left anterior, right anterior, left posterior and right posterior quadrants of the cavoatrial junction. Those located in the right anterior quadrant were in close relationship with the right phrenic nerve and the sinus node. Direction of myocardial sleeves was oblique, ascending from right to left, and descending through the posterior quadrants of the vein. Maximum highness was reached in the left anterior quadrant (15 to 56 mm, average 46 mm). Two patterns of distribution were observed: continuous in 9,4% and fenestrated in 90,6%. Conclusions: The extension of myocardial sleeves from right atrium to SVC is a constant fact, with homogeneous distribution, wrapping SVC around obliquely and reaching its maximum in the left quadrants of the vein. Myocardial breakthroughs were located mainly in the anterior quadrants of the cavoatrial junction. Their main relationships were established with the right phrenic nerve and sinus node.

Palavras-chave : ATRIAL FIBRILLATION; VENAE CAVAE.

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