The importance of atrial structure and fibers

Abstract

Atrial structures are important in the current era of cardiac interventions using percutaneous transcatheter procedures. Understanding their locations and component parts helps to reduce risks of procedural-related damage. The general arrangement of the myofibers that make up the atrial walls is reviewed to provide a morphologic basis for atrial conduction and potential substrates of arrhythmias. The right atrium, dominated by its appendage, is characterized by having an extensive array of pectinate muscles. These extend almost perpendicularly from the terminal crest. The left atrium has relatively smooth walls and a small tubular-shaped appendage. The myofibers show changes in orientations when traced through the thickness of the walls. Extensions of atrial myocardium onto the pulmonary veins and the superior caval vein are common. Apart from Bachmann's bundle, there are other muscular bridges of variable numbers and sizes that provide interatrial connections, connections between the left atrium and the coronary sinus, and connections between the muscular sleeves of the right pulmonary veins and the right atrium. The purpose of this review is to summarize the three-dimensional arrangement of gross atrial structures, the myoarchitecture and variations in muscular interatrial connections. These are important features in intra- and interatrial conduction.

Human left atrial appendage anatomy and overview to its clinical significance

“…The ridge lying between LSPV and the LAA is a critical structure during catheter ablation procedures (16) and has the potential of allowing interatrial conduction (8). The left lateral prominent ridge presence was seen in 51 specimens (91.1%) in present study.…”

“…It is a complex and multiform structure. It tends to have a tubular, narrow, long and crooked finger shape (1,(6)(7)(8)(9)(10). The heart specimens were evaluated in two different classifications.…”

Anatomic characteristics of left atrium and openings of pulmonary veins

“…Beside this, left atrium (LA) roof and septum are also important regions to improve the success rate of treating AF patients with catheter ablation (4,5). An overview of LA and proximal parts of pulmonary veins anatomy can provide useful information for surgical approaches, catheter ablation and radiologic examinations (1,(4)(5)(6)(7). The purpose of this paper was also to provide an anatomical review about LA and proximal parts of pulmonary veins.…”

Association Between Left and Right Atrial Remodeling With Atrial Fibrillation Recurrence After Pulmonary Vein Catheter Ablation in Patients With Paroxysmal Atrial Fibrillation

“…In addition, the difficulty in accurate evaluation of RA remodeling may contribute to the LA focus. On the other hand, the incomplete closure of the oval fossa 6 and the existence of interatrial muscular connections other than the Bachmann bundle 7 are well-known points of contact between both atria. Recent studies demonstrated that both LA and RA fibrosis with remodeling occur in patients with AF, and the intra-atrial pressure that reflects atrial remodeling of both atria may be related to AF recurrence.…”