Topographical anatomy of the right atrial appendage vestibule and its isthmuses

Abstract

Introduction: The right atrial appendage (RAA) vestibule is an area located in the right atrium between the RAA orifice and the right atrioventricular valve annulus and may be a target for invasive transcatheter procedures. Methods and Results: We examined 200 autopsied human hearts. Three isthmuses (an inferior, a middle, and a superior isthmus) were detected. The average length of the vestibule was 67.4 ± 10.1 mm. Crevices and diverticula were observed within the vestibule in 15.3% of specimens. The isthmuses had varying heights: superior: 14.0 ± 3.4 mm, middle: 11.2 ± 3.1 mm, and inferior: 10.1 ± 2.7 mm (p < .001). The superior isthmus had the thickest atrial wall (at midlevel: 16.7 ± 5.6 mm), the middle isthmus had the second thickest wall (13.5 ± 4.2 mm), and the inferior isthmus had the thinnest wall (9.3 ± 3.0 mm; p < .001). This same pattern was observed when analyzing the thickness of the adipose layer (superior isthmus had a thickness of 15.4 ± 5.6 mm, middle: 11.7 ± 4.1 mm and inferior: 7.1 ± 3.1 mm; p < .001). The average myocardial thickness did not vary between isthmuses (superior isthmus: 1.3 ± 0.5 mm, middle isthmus: 1.8 ± 0.8 mm, inferior isthmus: 1.6 ± 0.5 mm; p > .05). Within each isthmus, there were variations in the thickness of the entire atrial wall and of the adipose layer. These were thickest near the valve annulus and thinnest near the RAA orifice (p < .001). The thickness of the myocardial layer followed an inverse trend (p < .001). Conclusions: This study was the first to describe the detailed topographical anatomy of the RAA vestibule and that of its adjoining isthmuses. The substantial variability in the structure and dimensions of the RAA isthmuses may play a role in planning interventions within this anatomic region.

Atrial lead perforation early after device implantation—a case report and literature review

“…The first patient described validated this conclusion. The thickness of the atrial wall was proportional to the different heights of the RAA isthmuses, as well as the greatest near the valve annulus and the thinnest near the RAA orifice (49). Consistent with literature review, leads implanted in the anterior wall of the RA or the lateral wall of the RAA root have a higher risk of perforation.…”

Role of interatrial conduction in atrial fibrillation: Mechanistic insights from renewal theory–based fibrillatory dynamic analysis

“… 6 , 33 The Bachmann bundle rightward arm crosses the region of the cavoatrial junction superiorly around the region of the sagittal bundle, and inferiorly around the subepicardium of the RA vestibule (area between the RA appendage [RAA] orifice and the RA atrioventricular valve annulus). 33 , 34 The Bachmann bundle then courses across the anterior interatrial groove and leftward to the LAA, with superficial circular muscular fiber projections around the left lateral wall. 35 , 36 Other studies have suggested the role of high upper septum, which has been shown to form both structural and electrical connection to the mid portion of the Bachmann bundle.…”

Morphology and Position of the Right Atrioventricular Valve in Relation to Right Atrial Structures

“…When planning therapeutic procedures on the RAV, it is important to determine its morphology, position and neighboring cardiac structures [17]. The RAV annulus has important anatomical relationships with the right coronary artery, the acute marginal branch, the small cardiac vein (located within the vestibule of the right atrial appendage), the terminal crest, the cavo-tricuspid isthmus, the coronary sinus (and its ostium), the atrio-ventricular node and the aortic valve [21][22][23][24]. The above-mentioned structures are subject to injury, and clinicians must factor in their respective positions before attempting any invasive procedures.…”