Anatomical features and clinical importance of left atrial diverticula

Abstract

To assess the anatomical features and clinical importance of left atrial diverticula and atrial accessory appendages in patients undergoing cardiac computed tomography with multidetector computed tomography. A total of 1305 consecutive patients (385 female, 29.5%; 920 male, 70.5%) were assessed using electrocardiogram-gated computed tomography between May 2010 and June 2013. The anatomical features and the prevalences of left atrial diverticula and left atrial accessory appendages were retrospectively assessed by four radiologists. The relationships between the prevalence and size of the diverticula and the age and gender of the patients were assessed. Among the 1305 patients, 610 (46.7%) exhibited 708 left atrial diverticula, and 62 (4.8%) exhibited left atrial accessory appendages. The most common locations of the left atrial diverticula were the right anterior superior wall (n = 328, 46.3%) and the lateral superior wall (n = 96, 13.5%). In addition to classical cystic and tubular diverticula, 49 (3.7%) of the patients exhibited mixed (cystic-tubular), conical, or hook-shaped diverticula and diverticular forms containing mural calcifications. There was no significant relationship between the prevalence of diverticula and the age and gender of the patients (P > 0.05). In addition to tubular and cystic diverticula, the left atrial wall can host different diverticular forms (such as mixed, conical, calcific, and hook shaped). It could be beneficial to assess the left atrium using MDCT to determine the source of emboli in cryptogenic embolism and to reduce complications associated with interventional procedures performed for left atrial arrhythmias.

Left atrial diverticula: Innocent bystanders or wolves in sheep's clothing?

“…There is also no uniform methodology for describing their anatomical locations. To identify locations, a method of left atrial segmenting‐ consisting of division of the anterior and posterior wall in four equal quadrants‐ was introduced 3 . However, there are no anatomical boundaries used to split these four quadrants.…”

“…However, these names are used interchangeably and accurate definitions discriminating these different types of structures are often not provided. For example, small diverticula in the left atrium were labeled as type I LAAA and large diverticula or aneurysms as type II LAAA 3,4,7,10 . In the right atrium, structures extending from the endocardial cavity were not only labeled as diverticula or right atrial aneurysms but also as ‘idiopathic dilatations 11 .…”

“…Sites at which congenital LAD have been observed include the LA appendage and the LA posterior wall 15,16 . LA diverticula of unknown origin have been found at the anterior wall, 8 antero‐superior wall, 1,3‐6 and the veno‐atrial junction of the right superior pulmonary vein 17 . In the right atrium, diverticula have been observed at the distal part of the right atrial appendage, right atrial free wall, 18 within the coronary sinus, mid cardiac vein, 13,19 and the right atrial posterior wall 14 …”

“…As indicated by their name, they originate from the LAA and they are therefore regarded as congenital in nature (Figure 3). 4,23 Indeed, they have been found at the antero‐superior and 6 lateral wall 3,4 . However, in some reports atrial structures observed at sites not limited to the region of the LAA 6 were also labeled as LAAA.…”

“…Reports on the correlation between the presence of LAD and development of AF are univocal in outcome; there are no differences in prevalences of LAD between patients with sinus rhythm and AF 1‐6 . Thus, it is unlikely that LAD could potentially be wolves in sheep clothing.…”