The anatomy of the interatrial septum: A transesophageal echocardiographic study

Schwinger, Matthew E.; Gindea, Aaron J.; Freedberg, Robin S.; Kronzon, Itzhak

doi:10.1016/s0002-8703(05)80191-7

Cited by 61 publications

(28 citation statements)

References 20 publications

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“…30,31 The location and size of the oval fossa varies from case to case, as does the profile or prominence of the muscular rim. 32 Furthermore, abnormalities of the thorax or of the cardiovascular system such as kyophoscoliosis or marked left ventricular hypertrophy may result in displacement of the fossa ovalis. 33 Cases with patches, occluder devices, aneurysmal valves of the oval fossa, and thickly fibrosed septum that may be due to previous transseptal procedures are particularly challenging to perforate.…”

Section: Septal Componentmentioning

confidence: 99%

Left Atrial Anatomy Revisited

Cabrera²,

Sánchez‐Quintana³

2012

Circ: Arrhythmia and Electrophysiology

305

249

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R ecent decades have seen rapid developments in arrhythmia treatment, especially the use of catheter ablation. Although the substrates of atrial fibrillation, its initiation and maintenance, remain to be fully elucidated, catheter ablation in the left atrium has become a therapeutic option for patients with this arrhythmia. With ablation techniques, various isolation lines and focal targets are deployed; the majority of these are anatomic approaches. It has been over a decade since we published our first article on the anatomy of the left atrium relevant to interventional electrophysiologists. 1 Our aim then, as now, was to increase awareness of anatomic structures inside the left atrium. In this review of anatomy, we revisit the left atrium, inside as well as outside, for a better understanding of the atrial component parts and the spatial relationships of specific structures. Location and Atrial WallsViewed from the frontal aspect of the chest, the left atrium is the most posteriorly situated of the cardiac chambers. Owing to the obliquity of the plane of the atrial septum and the different levels of the orifices of the mitral and tricuspid valves, the left atrial chamber is more posteriorly and superiorly situated relative to the right atrial chamber. The pulmonary veins enter the posterior part of the left atrium with the left veins located more superior than the right veins. The transverse pericardial sinus lies anterior to the left atrium, and in front of the sinus is the root of the aorta. The tracheal bifurcation, the esophagus, and descending thoracic aorta are immediately behind the pericardium overlying the posterior wall of the left atrium. Further behind is the vertebral column.Following the direction of blood flow, the atrial chamber begins at the pulmonary veno-atrial junctions and terminates at the fibro-fatty tissue plane that marks the atrioventricular junction at the mitral orifice. The walls of the left atrium are muscular and can be described as superior, posterior, left lateral, septal (or medial), and anterior, as suggested by McAlpine, 2 who drew attention to the importance of describing the heart in its anatomic position in the chest, in the orientation he termed "attitudinal," which is the appropriate terminology for cardiac interventionists. 3 The left atrium is relatively smooth-walled on its internal aspect ( Figure 1A), but its walls are not uniform in thickness. The roof or superior wall is in close proximity to the bifurcation of the pulmonary trunk and the right pulmonary artery. The thickness of its muscle component measured transmurally ranges from 3.5 to 6.5 mm (mean, 4.5Ϯ0.6 mm) in formalin-fixed heart specimens. 4 The thickness of the lateral wall ranges between 2.5 and 4.9 mm (mean, 3.9Ϯ0.7 mm). The anterior wall, related to the aortic root, ranges from 1.5 to 4.8 mm (mean, 3.3Ϯ1.2 mm) thick, but it can become very thin at the area near the vestibule ( Figure 1B) of the mitral annulus, diminishing to an average thickness of 2 mm. Importantly, there is an area of the anterio...

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Section: Septal Componentmentioning

confidence: 99%

Left Atrial Anatomy Revisited

Cabrera²,

Sánchez‐Quintana³

2012

Circ: Arrhythmia and Electrophysiology

305

249

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“…The floor of the oval fossa varies considerably in dimensions as does the thickness of the muscular rim (Schwinger et al, 1990). Prominent muscular rims are helpful to interventionists to feel a ''jump'' as the tip of the catheter drops into the flap valve allowing the valve to ''tent'' into the left atrium when carrying out transseptal punctures.…”

Section: Structure Of the Atrial Septummentioning

confidence: 99%

The importance of atrial structure and fibers

2008

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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.

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“…The septum primum at the level of the fossa ovalis has been shown to average only 1.8Ϯ0.7 mm in thickness, whereas the anterior and posterior regions of the septum average 6Ϯ2 mm and range from 2 to 20 mm in thickness. 19 Histological cross sections of the midseptal wall have shown connective tissue, fat, and vessels separating the RA and LA septal surfaces. 5…”

Section: Anatomic Correlationsmentioning

confidence: 99%

Human Study of Biatrial Electrical Coupling

et al. 2004

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Background-The relative contribution of the atrial septum and interatrial connections to biatrial activation is a fundamental concept of human cardiac electrophysiology that has yet to be fully characterized. The purpose of the present study was to determine how both atria are coupled electrically. Methods and Results-Twenty patients (16 men; mean age 54Ϯ11years) with a history of symptomatic atrial fibrillation (AF) underwent simultaneous biatrial noncontact mapping before catheter ablation of AF. The multiple electrode array catheters were positioned, respectively, in the left atrium (LA; transseptally) and the right atrium (RA). In all but 2 patients, isopotential maps revealed that endocardial septal activations of the RA and LA were separate, independent, and asynchronous of each other. Interatrial conduction was related to the site of initial atrial depolarization, revealing conduction over Bachmann's bundle in all patients during sinus rhythm, high RA pacing, and pacing from the LA appendage. Pacing from the coronary sinus was associated with conduction over the interatrial connection at the level of the coronary sinus in all patients, and conduction over Bachmann's bundle also occurred in 5 (26%) of 19 patients. Interatrial conduction over the fossa ovalis occurred in only 2 (2%) of the 116 segments analyzed. Conclusions-Electrical coupling of the RA and LA in humans is predominantly provided by muscular connections at the level of Bachmann's bundle and the coronary sinus. The true septum (the fossa ovalis and its limbus) of the RA and LA is asynchronous and discordant, usually without contralateral conduction during sinus rhythm or atrial pacing.

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The anatomy of the interatrial septum: A transesophageal echocardiographic study

Cited by 61 publications

References 20 publications

Left Atrial Anatomy Revisited

Left Atrial Anatomy Revisited

The importance of atrial structure and fibers

Human Study of Biatrial Electrical Coupling

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