Endocardial irregularities of the left atrial roof as seen on coronary CT angiography

A meta-analysis of the accessory left atrial appendage and the left atrial diverticulum

Left atrial (LA) structures, including the accessory left atrial appendage (aLAA) and left atrial diverticulum, have been studied based on their prevalence, shape, and association with arrhythmia and thrombi formation. A pooled prevalence with morphometric data has not been determined in previous research. Our goal is to provide structured, clinically relevant information on said structures for clinical practitioners to use in their daily work. We propose that morphometric data of additional LA structures is necessary when considering the possible complications during cardiac interventions. We conducted a meta-analysis of all relevant studies which used electrocardiogram (ECG)-gated computed tomography (CT) imaging to determine the prevalence of LA structures and record their morphometric characteristics as well as the presence of thrombi. Data were extracted from 19 studies (n = 6643 hearts). The pooled prevalence estimate of left atrial diverticulum and/or aLAAs were reported from 14 studies and was 28.8%. The most common location noted was anterosuperior in the LA with 70.2% of structures found there. Data regarding thrombi presence in left atrial diverticulums or aLAAs were extracted from 11 studies and a thrombus was present in 0.2%. The prevalence rates of aLAAs and left atrial diverticulums are essential in performing uncomplicated cardiac interventions and reducing risk of electrophysiological procedures. Our findings show a considerable prevalence of LA structures in varying populations, provides information regarding the general characteristics of said structures, and does not support the previously theorized associated risk of thrombus formation in relation to LA structure presence.

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

INTRODUCTION

The finding of left atria diverticula (LAD) on cardiac computed tomography images obtained from patients with atrial fibrillation (AF) referred for pulmonary vein isolation is not uncommon. Prior studies reporting on LAD do not always provide definitions of LAD resulting in confusion with other anatomical structures such as left atrial accessory appendages (LAAA) and atrial aneurysms. The aim of this review is to identify an accurate definition of LAD and to describe distinctive properties between LAD and other left atrial structures, such as LAAA and aneurysms. Also, the relation between LAD and development of atrial tachyarrhythmias is discussed.

METHODS

PubMed was searched for studies reporting on atrial aneurysms, left atrial diverticula, left atrial accessory appendages and atrial congenital aneurysms, resulting in 36 papers.

RESULTS

LAD can be distinguished from LAAA by taking into account embryologic origins of the left atrium and their locations, resulting in the following definitions: (a) LAAA are contractile, trabeculated structures with circumscriptive ostia and narrow necks, originating from the primitive atria, (b) LAD are contractile, sac like structures with either smooth or trabeculated inner surfaces, circumscriptive ostia, narrow necks, and variable morphologies, originating from the embryologic common pulmonary vein, that incorporates into the LA, and (c) atrial aneurysms are non-contractile structures with wide necks and sac like bodies. There are no differences in prevalences of LAD between patients with sinus rhythm and AF.

CONCLUSION

The pathophysiology of LAD is not yet fully understood. It is unlikely, that LAD are related to the development of atrial tachycardia's and AF by either being a source of ectopic activity or being part of an arrhythmogenic substrate. No differences in LAD prevalences between patients with sinus rhythm and AF have been found. Thus, it is unlikely that LAD could potentially be wolves in sheep's clothing.

The characteristics of left atrial diverticula in normal sinüs rhythm patients

PURPOSE

The purpose of this study was to evaluate the prevalence, location, size and morphological characteristics of left atrial diverticula using electrocardiographically gated multi-detector computed tomography in patients with normal sinus rhythm.

METHODS

Electrocardiographically gated cardiac multi-detector computed tomography was performed in 93 patients with normal sinus rhythm. The prevalence, number, size, morphological characteristics and location of left atrial diverticula were recorded.

RESULTS

A total of 72 left atrial diverticula were diagnosed in 45 (48.4%) of the 93 patients in this study. Of these 72 diverticula, 66 (91.7%) were cystiform and 6 (8.3%) were tubiform. Anterosuperior wall, left lateral wall and septum were the most common locations of these left atrial diverticula (n = 42, 58.3%; n = 22, 15.3% and n = 7, 9.7%, respectively).

CONCLUSION

Diverticula are common variations. The discovery of these structures is relatively new and their clinical significance remains unclear. They are generally asymptomatic but although not supported by many studies, in some case reports they are claimed to be associated with arrhythmias and thromboembolism. In addition, it is theoretically reasonable to think that they may cause complications during interventional procedures. Better understanding of these structures has the potential to improve management strategies and reduce potential complications. Therefore, they should be reported during routine cardiac computed tomography.

Anatomical features and clinical importance of left atrial diverticula: MDCT findings

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.

Congenital absence of the pericardium and its mimics

Congenital absence of the pericardium is a rare entity, with less than 400 cases reported in the literature. Pericardial absence is typically left sided, which results in herniation of the great vessels or portions of the heart. Patients may be asymptomatic, typical for complete defects, or can present with various degrees of chest pain in the setting of partial absence and strangulation. The finding may be isolated or associated with complex heart disease. We present a number of cases of pericardial absence that show isolated right- and left-sided defects, as well as entities in the differential diagnosis. Early recognition may decrease morbidity and mortality, resulting from delay in proper treatment.

Cardiac CT assessment of left atrial accessory appendages and diverticula

OBJECTIVE

The purpose of this study is to describe the prevalence, morphology, size, and location of left atrial abnormalities including diverticula and accessory appendages in consecutive patients undergoing cardiac-gated CT for coronary artery evaluation.

MATERIALS AND METHODS

Routine retrospectively gated contrast-enhanced 64-MDCT angiography (0.75-mm collimation, 330-milliseconds gantry rotation time) was performed in 529 consecutive patients. CT data sets were evaluated using axial, sagittal, coronal, and interactive multiplanar reconstructions; maximum intensity projections (MIPs); and interactive volume rendering. The presence, type, and location of left atrial appendages and diverticula were recorded.

RESULTS

One hundred twenty-one patients had left atrial accessory appendages (n = 20) or left atrial diverticula (n = 81) or both (n = 20). One hundred four left atrial diverticula were found in 101 of the 529 patients (20%) and 44 accessory appendages in 41 patients (8%). Of the atrial diverticula, 88% were superior and anterior, 9% were right lateral superior, and 3% were inferior. Of accessory appendages, 34% were inferior posterior, 32% were left inferior, 18% were superior anterior, 14% were inferior posterior, and 2% were right inferior posterior. The average sizes of diverticula were 6.4 +/- 2.5 x 6.2 +/- 2.4 mm, and accessory appendages were 4.9 +/- 2.1 x 3.9 +/- 2.4 mm.

CONCLUSION

Left atrial diverticula and accessory appendages are commonly found on cardiac-gated CT.

Classic images: Cardiac computed tomography

Cardiac computed tomography (CT) has evolved into a valuable clinical tool for cardiac evaluation. Cardiac CT is increasingly used for imaging of the coronary arteries for the evaluation of (suspected) coronary artery disease, but many other cardiac structures may be the topic for CT investigation. This article reviews general indications for cardiac CT imaging. Common variants and pathologies of the cardiovascular system are illustrated by clinical examples.