The anatomical study of left atrium diverticulum by multi-detector row CT

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.

Association between pouch morphology, cardiovascular risk factors and ischemic brain lesions in patients with left-sided septal pouches

BACKGROUND

Left atrial outpouching structures such as left atrial diverticula (LADs) and left-sided septal pouches (LSSPs) might be a source of cryptogenic stroke. This imaging study evaluates the association between pouch morphology, patient comorbidities and ischemic brain lesions (IBLs).

METHODS

This is a retrospective single-center analysis of 195 patients who received both a cardiac CT and a cerebral MRI. LADs, LSSPs, and IBLs were retrospectively identified. Size measurements included pouch width, length and volume for LADs and circumference, area and volume for LSSPs. The association between LADs/LSSPs, IBLs and cardiovascular comorbidities was determined by univariate and bivariate regression analyses.

RESULTS

The prevalence and mean volume were 36.4% and 372 ± 569 mm³ for LSSPs, and 40.5% and 415 ± 541 mm³ for LADs. The IBL prevalence was 67.6% in the LSSP group and 48.1% in the LAD group. LSSPs had 2.9-fold increased hazards of IBLs (95%CI: 1.2-7.4, p = 0.024), and LADs showed no significant correlation with IBLs. Size measurements had no impact on IBLs. A co-existing LSSP was associated with an increased prevalence of IBLs in patients with coronary artery disease (HR: 1.5, 95%CI: 1.1-1.9, p = 0.048), heart failure (HR: 3.7, 95%CI: 1.1-14.6, p = 0.032), arterial hypertension (HR: 1.9, 95%CI: 1.1-3.3, p = 0.017), and hyperlipidemia (HR: 2.2, 95%CI: 1.1-4.4, p = 0.018).

CONCLUSION

Co-existing LSSPs were associated with IBLs in patients with cardiovascular risk factors, however, pouch morphology did not correlate with the IBL rate. Upon confirmation by further studies, these findings might be considered in the treatment, risk stratification, and stroke prophylaxis of these patients.

Is there an association between left atrial outpouching structures and recurrence of atrial fibrillation after catheter ablation?

Objective

The aim of this study was to investigate the impact of left atrial diverticula (LADs), left sided septal pouches (LSSPs) and middle right pulmonary veins (MRPVs) on recurrent atrial fibrillation (rAF) in patients undergoing laser pulmonary vein isolation procedure (PVI).

Material and methods

This retrospective study enrolled 139 patients with pre-procedural multiple detector computed tomography (MDCT) imaging and 12 months follow-up examination. LADs, LSSPs and MRPV were identified by two radiologists on a dedicated workstation using multiplanar reconstructions and volume rendering technique. Univariate and bivariate regression analyses with patient demographics and cardiovascular risk factors as covariates were performed to reveal independent factors associated with rAF.

Results

LADs were recorded in 41 patients (29%), LSSPs in 20 (14%) and MRPVs in 15 (11%). The right anterosuperior wall of the left atrium was the most prevalent location of LADs (68%). rAF occured in 20 patients, thereof, 15 exhibited an outpouching structure of the left atrium (LAD: 9, LSSP: 2 and MRPV: 3). Presence of an LAD (HR: 2.7, 95%CI: 1.0–8.4, p = 0.04) and permanent AF (HR: 4.8, 95%CI: 1.5–16.3, p = 0.01) were independently associated with rAF.

Conclusions

LAD, LSSP and MRPV were common findings on pre-procedural cardiac computed tomography. LADs were revealed as potential independent risk factor of rAF, which might be considered for treatment planning and post-treatment observation.

Cardiac CT evaluation of left atrial diverticulum and accessory appendage

Background

The aim of this study was to evaluate the prevalence, location, size, and morphological features of the left atrial accessory appendage and diverticulum with cardiac computed tomography. Cardiac computed tomography obtained consecutively from 1415 patients with normal ECG findings during a 2-year period were analyzed. Left atrial appendage and diverticulum type, location, and size were recorded and analyzed according to age and gender.

Results

Cardiac computed tomography of 1415 (796 males and 619 females) participants aged 44.1 + 12.2 years old were re-evaluated, and 238 atrial diverticulum were found in 234 (16.5%) patients, accessory appendage in 93 (6.5%), and atrial diverticula and accessory appendage together in eight (0.56%) patients. The atrial diverticulum was most frequently observed in the anterosuperior localization (n = 157, 49.2%). One hundred and twenty-three (52%) of the atrial diverticulum were cystic, and 107 (45%) were tubular form. Accessory appendage was observed most frequently in the anterior superior location (n = 65, 20.4%).

Conclusions

The frequency of left atrial diverticulum was found to be 16%, and the frequency of accessory appendage was 6%, consistent with the majority of the literature. Left atrial diverticulum and accessory appendage were detected more frequently in men than in women. Cystic form is more common in left atrial diverticulum.

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.

Multidetector computed tomography in planning the treatment of atrial fibrillation

OBJECTIVE

To know the anatomy of the pulmonary veins (PVs) by multidetector computed tomography (MDCT) in patients with atrial fibrillation (AF) prior to ablation.

MATERIALS AND METHODS

MDCT was performed in 89 patients with AF, analyzing the number of PVs, accessory variants and veins, diameter and ostial shape, distance to the first bifurcation and thrombus in the left atrial appendage.

RESULTS

The most frequent venous pattern was 4 PVs (two right and two. left) in 49 patients (55.1%). The superior veins had a statistically significant greater mean ostial diameter than the inferior veins (Right Superior Pulmonary Vein (RSPV)> Right Inferior Pulmonary Vein (RIPV); p=0.001 and Left Superior Pulmonary Vein (LSPV)> Left Inferior Pulmonary Vein (LIPV); p<0.001). The right pulmonary veins ostial diameters were significantly larger than the left pulmonary veins ostial diameters (RSPV> LSPV; p<0.001 and RIPV> LIPV; p<0.001). The most circular ostium was presented by the VPID (ratio: 0.885) compared to the LIPV (p<00.1) and LSPV (p<0.001). The superior veins had a statistically significant greater mean distance to first bifurcation than the inferior veins (RSPV> RIPV; p=0.008 and LSPV> LIPV; p=0.038). Mean distance to first bifurcation has been greater in left PVs respect to the right PVs (LSPV> RSPV; p<0.001and LIPV> RIPV; p<0.001). Other findings found in AI: diverticula (30), accessory auricular appendages (5), septal aneurysms (8), septal bags (6) and 1 thrombus in the left atrial appendage.

CONCLUSION

MDCT prior to ablation demonstrates the anatomy of the left atrium (LA) and pulmonary veins with significant differences between the diameters and morphology of the venous ostia.

Neonatal repair of left atrial diverticulum with gigantic thrombus without cardiopulmonary bypass

A 5-day-old neonate with coarctation of the aorta, hypoplastic aortic arch, large apical muscular ventricular septal defect, and patent ductus arteriosus developed pulmonary over-circulation and systemic hypoperfusion underwent bilateral pulmonary artery banding through median sternotomy as a part of hybrid stage I palliation. At operation, left atrial diverticulum with gigantic thrombus formation at the base of the left atrial appendage was incidentally detected by intraoperative direct echocardiography, and therefore, was successfully resected with the whole thrombus inside it without use of cardiopulmonary bypass. Histopathological finding was compatible with diverticulum. The patient was free from atrial arrhythmia and recurrent thrombus formation.

Assessments of pulmonary vein and left atrial anatomical variants in atrial fibrillation patients for catheter ablation with cardiac CT

OBJECTIVES

To provide a road map of pulmonary vein (PV) and left atrial (LA) variants in patients with atrial fibrillation (AF) before catheter ablation procedure using cardiac CT.

METHODS

Cardiac CT was performed in 1420 subjects for accurate anatomical information, including 710 patients with AF and 710 matched controls without AF. PV variants, PV ostia and spatial orientation, LA enlargement, and left atrial diverticulum (LAD) were measured, respectively. Differences between these two groups were also respectively compared. Some risk factors for the occurrence of LAD were analyzed.

RESULTS

In total, PV variants were observed in 202 (28.5 %) patients with AF patients and 206 (29.0 %) controls without AF (p = 0.8153). The ostial sizes of all accessory veins were generally smaller than those of the typical four PVs (p = 0.0153 to 0.3958). There was a significant difference of LA enlargement between the AF and control groups (36.3 % vs. 12.5 %, p < 0.0001), while the prevalence of LAD was similar in these two groups (43.2 % vs. 41.9 %, p = 0.6293).

CONCLUSION

PV variants are common. Detailed knowledge of PVs and LA variants are helpful for providing anatomical road map to determine ablation strategy.

KEY POINTS

• PVs variants are helpful for providing anatomical road map to ablation. • PV variants are common. • DSCT could recognize these anatomic features before ablation as a non-invasive imaging.

Electrophysiological characteristics of left atrial diverticulum in patients with atrial fibrillation: electrograms, impedance and clinical implications

BACKGROUND

Left atrial diverticulum (LAD) is not rare in patients with atrial fibrillation (AF). Recent reports focused on its morphology however data on its electrophysiological characteristics are lacking. Our study aims to investigate the electrogram and impedance features of LAD.

METHODS

This study included 24 patients (mean age, 58.5 ± 10.7 years) with LAD undergoing catheter ablation for AF and 24 gender-and-age-matched individuals without LAD as controls. A bipolar LAD electroanatomic map was acquired in sinus rhythm from all study participants. Points were acquired for diverticulum in the LAD group and for corresponding areas in the control group. Electrogram deflections were counted, bipolar voltage and impedance were measured for each point, and average ∆ impedance and highest ∆ impedance were calculated.

RESULTS

A total of 234 points were collected in the two groups. In the LAD vs. control group, median (Q1, Q3) of electrogram deflections was 6 (5, 7) and 4 (4, 5) (P<0.0001), respectively, voltage was not significantly different (1.58 ± 0.68 mV vs. 1.28 ± 0.65 mV, P=0.10), and average ∆ impedance was significantly higher in the LAD group (19.5 ± 9.0 Ω vs 3.9 ± 1.7 Ω, P<0.0001). A cut-off value of 9.5 Ω for ∆ impedance predicted LAD with sensitivity, specificity, and positive and negative predictive values of 83.5%, 92.8%, 92.1% and 84.9%, respectively.

CONCLUSIONS

Electrogram was more fractionated and impedance was higher at LAD than in corresponding areas without LAD, which might help to differentiate LAD during catheter ablation for AF.

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.

Lack of association between stroke and left atrial out-pouching structures: results of a case-control study

Background and Purpose

Clinical significance of out-pouching structures of the left atrium (LA) as potential embolic sources remains unclear. We sought to evaluate the association between stroke and LA out-pouching structures.

Methods

A case-control study was conducted to assess the prevalence of LA out-pouching structures in subjects with and without stroke. Case subjects were 270 stroke patients who had undergone cardiac CT. Control subjects were 270 age- and sex-matched patients without a history of stroke and who had undergone cardiac CT. Presence of LA out-pouching structures was determined by ECG-gated cardiac CT. The location of out-pouching structures was categorized as near Bachmann bundle, anterior, inferoseptal, inferior, and lateral. The prevalence, number and location of out-pouching structures and clinical characteristics were compared between the two groups.

Results

One hundred sixty eight out-pouching structures were identified in 139 stroke patients (51%), while a total of 169 out-pouching structures were found in 155 control patients (57%) (p=0.1949). The prevalence of LA out-pouching structures with different locations was not significantly different between the stroke group and control group. In the stroke group, the prevalence of out-pouching structures was not significantly different by subtypes of ischemic stroke and the prevalence of LA out-pouching structures was not different between patients with atrial fibrillation (AF) and without AF.

Conclusion

The left atrial out-pouching structures are commonly seen in a population with and without stroke with similar prevalence. Our study suggests that LA out-pouching structures are not significant risk factors of stroke.

Left Atrial Diverticula in Patients Referred for Radiofrequency Ablation of Atrial Fibrillation

Background—

The anatomic features of left atrial diverticula (LAD) are still unclear in patients with atrial fibrillation (AF). The purpose of this study was to evaluate the prevalence and morphological characteristics of LAD in patients referred for radiofrequency transcatheter ablation of AF with dual-source computed tomography.

Methods and Results—

Dual-source computed tomography images were obtained in 214 patients referred for AF catheter ablation and 214 sex- and age-matched control subjects. Images were analyzed to determine the prevalence and morphological characteristics of LAD and their relationship with adjacent pulmonary veins and left atrial appendage. In AF patients 77 (36.0%) (95% confidence interval, 29.6–42.4%) had 90 LAD, whereas in control subjects 70 (32.7%) (95% confidence interval, 26.4–39.0%) had 81 LAD ( P =0.551). In patients with AF, LAD locations were right anterosuperior (47.8%), left anterosuperior (8.9%), left lateral (32.2%), interatrial septum (4.4%), right inferior (5.6%), and posterosuperior (1.1%) walls, respectively. The mean size of LAD was 5.3±2.9×5.6±3.3 mm. The wall of the LAD was much thinner than that of adjacent left atrium (0.89±0.46 versus 2.39±0.83 mm). Most LAD were located close to a pulmonary vein or atrial appendage ostium, with a mean distance of 8.7–13.1 mm.

Conclusions—

LAD are common, with a prevalence of 36.0% in patients with AF, which is not statistically greater than that in patients without AF. Thin-walled LAD are more commonly located on the superior anterior wall of left atrium and close to common ablation sites.

Congenital left ventricular diverticulum manifested as T-wave inversion in a child

Congenital diverticulum of the ventricle is a rare disease, but most cases of congenital left ventricular diverticula are asymptomatic. We present a child with congenital left ventricular diverticulum whose routine electrocardiographic examination showed T-wave inversion in inferior and V4 to V6 leads. He was successfully repaired surgically.

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.