Year : 2012  |  Volume : 15  |  Issue : 2  |  Page : 161--162

Anomalous ridge on the left atrial side of the atrial septum

Yukitaka Shizukuda1, James Muth2, Curtis Chaney3, Mehran Attari1,  
1 Division of Cardiovascular Diseases, Department of Internal Medicine, University of Cincinnati; Division of Cardiology, Cincinnati VA Medical Center, Cincinnati, OH, USA
2 Division of Cardiovascular Diseases, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA
3 Division of Cardiology, Cincinnati VA Medical Center, Cincinnati, OH, USA

Correspondence Address:
Yukitaka Shizukuda
Division of Cardiovascular Diseases, Department of Medicine, University Hospital, University of Cincinnati, 231 Albert Sabin Way, ML 0542 Cincinnati, OH 45267 0542

How to cite this article:
Shizukuda Y, Muth J, Chaney C, Attari M. Anomalous ridge on the left atrial side of the atrial septum.Ann Card Anaesth 2012;15:161-162

How to cite this URL:
Shizukuda Y, Muth J, Chaney C, Attari M. Anomalous ridge on the left atrial side of the atrial septum. Ann Card Anaesth [serial online] 2012 [cited 2023 Jan 29 ];15:161-162
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Full Text

A 75-year-old male with a history of persistent atrial fibrillation, type II diabetes mellitus, hypertension and hypercholesterolemia underwent transesophageal echocardiography (TEE) to evaluate for a left atrial appendage thrombus prior to direct current cardioversion. The TEE was performed using a real-time 3-dimensional (3D) TEE probe connected to the iE 33 Philips ultrasound system (Philips Healthcare, Andovor, MA, USA). The 3D TEE revealed a ridge-like structure on the left atrial side of the atrial septum protruding into the left atrial lumen [Figure 1]a. This ridge was formed along the superior edge of the oval fossa in the left atrium, and extended to the left atrial free wall medially and superiorly [Figure 1]b. This ridge-like structure overhung posteriorly, creating a hollow-like structure [Figure 1]c and d. Although we did not perform an agitated saline contrast study, which is more sensitive than color Doppler, to evaluate a right to left atrial shunt, the color Doppler interrogation of this ridge did not reveal interatrial shunting. No thrombus or spontaneous echo contrast was noted beneath the overhung area. The atrial septum appeared normal from the right atrial side [Figure 2]a and b.{Figure 1}{Figure 2}

In contrast to the ridge-like structures of the right atrium, such as an Eustachian valve or crista terminalis, ridge-like structures on the left atrial side have not been well described. [1],[2] In the left atrial side of the atrial septum, redundancy of atrial septal membrane forming the oval fossa is often noted, and atrial septal aneurysm is common. [1],[2] Sweeny et al. describe a network of muscular trabeculations that can be seen in the left atrial septum. Some of these may be seen along the anterior border of the oval fossa representing the remnants of the ostium secudum, and have been named the cresentic muscular arch. [3],[4] However, a prominent membrane-like ridge formation along the oval fossa that overhangs and extends to the atrial free wall superiorly has not been clearly documented in the previous literature. In addition, this variation could interfere with navigating guiding wires and catheters in the left atrium through transeptal approach. Recently, two discrete types of mesenchymal cells have been identified that form the mesenchymal cap that closes the primary atrial foramen by fusing with the arterioventricular cushions. [5] One population is from the endocardium and the other is from the dorsal mesocardium outside the heart, indicating that both intracardiac and extracardiac mesenchymal cells participate in the formation of the atrial septum. [5] This study underscores the complexity of atrial septum formation and a need for further understanding of this embryonic development. Our case is a very rare anomaly. The number of cardiac patients who undergo inverventional transeptal approach has risen substantially over the past few years, further underlying the importance of understanding left atrial anatomy and anomalies. Delineation of complex atrial septal structures before such procedures by TEE with the aid of 3-dimensional TEE informs the cardiologist of potential procedural challenges and improves patient safety. [6]


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