The Architecture of the Atrial Musculature Between the Orifice of the Inferior Caval Vein and the Tricuspid Valve: The Anatomy of the Isthmus

Abstract

There are considerable anatomic variations in the atrial wall that comprises the so-called isthmus. The presence of recesses and membranous areas in some hearts and the variations in arrangement of the subendocardial fibers are relevant in improving understanding of conduction in this area.