Atrial septal defects: Magnetic resonance and computed tomography appearances

Pediatric Cardiac MR Imaging:: Practical Preoperative Assessment

Prevalence of patients with congenital heart disease (CHD) is rapidly increasing due to continuous advancements in diagnostic techniques and medical or surgical treatment approaches. Along with cardiac computed tomography angiography, cardiac magnetic resonance (CMR) serves as a fundamental imaging modality for pre-surgical planning in patients with CHD, as CMR allows for the evaluation of cardiac and great vessel anatomy, biventricular function, flow dynamics, and tissue characterization. This information is essential for risk-assessment and optimal timing of surgical interventions. This article discusses the current role of pediatric cardiac MR imaging as a practical preoperative assessment tool in the pediatric population.

Atrial shunts: presentation, investigation, and management, including recent advances in magnetic resonance imaging

Atrial shunts are a common finding in both paediatric and adult populations. Recent developments in advanced imaging have widened the options for diagnosis and evaluation of such shunts. This paper reviews the various types of interatrial communications, discusses the features of clinical presentation in adults and children, and provides an overview of the clinical assessment including physical examination, electrocardiography, echocardiography, cardiac catheterisation, computed tomography, and magnetic resonance imaging. Focus will be placed on recent developments in magnetic resonance imaging that may improve the non-invasive evaluation of atrial shunts.

Cardiac MRI: Part 1, cardiovascular shunts

OBJECTIVE

MRI plays an important role in the morphologic and functional evaluation of cardiovascular shunts. Good spatiotemporal resolution, inherent contrast resolution, wide FOV, and multiplanar imaging capabilities make MRI an ideal tool in the investigation of cardiovascular shunts. The velocity-encoded phase-contrast sequence is used in the quantification of a shunt and the steady-state free precession (SSFP) sequence is used in the assessment of the functional impact of a shunt. In this article, the role of MRI in the evaluation of cardiovascular shunts and their respective MRI appearances are described and illustrated.

CONCLUSION

MRI can identify and characterize septal defects, quantify shunts and their impact on cardiac function, and help in the selection of appropriate candidates for percutaneous device placement.

Interatrial shunt: diagnosis of patent foramen ovale and atrial septal defect with 64-row coronary computed tomography angiography

PURPOSE

The aim of this study was to investigate the frequency with which interatrial shunts are found during routine coronary computed tomography (CT) angiography and to describe imaging characterizations of patent foramen ovale (PFO), atrial septal defect (ASD), and atrial septal aneurysm (ASA).

MATERIALS AND METHODS

A total of 1081 adult patients were evaluated retrospectively for interatrial shunting; 77 were excluded from the study. CT diagnosis of PFO was defined as (1) a channel-like appearance of the interatrial septum (IAS) and (2) a contrast agent jet flow from the left atrium (LA) to the right atrium (RA). ASD was defined as (1) the IAS resembling a membrane with a hole and (2) a contrast jet flow between the two atria. ASA was identified by detecting a minimum 10-mm protrusion of the LA beyond the IAS into the RA.

RESULTS

Among 1004 patients, 86 patients (8.6%) were diagnosed to have PFO. Another 23 patients (2.3%) had a hole in the IAS and were diagnosed as having ASD: 21 with an ostium secundum-type ASD and 2 with the sinus venosus type. ASA accompanied ASD in three patients.

CONCLUSION

Electrocardiography-gated CT using the saline-chaser contrast injection technique that is routinely used for coronary arterial imaging can be used to detect interatrial shunts. The technique can also serve as a method for differentiating PFO, ASD, and ASA.

Transseptal left heart catheterization and the incidence of persistent iatrogenic atrial septal defects

INTRODUCTION

Access to the left atrium for invasive and interventional cardiac procedures requires a transseptal (TS) puncture that creates an iatrogenic atrial septal defect (iASD). The utilization of TS access is increasing in cardiology, and the frequency of iASD is, therefore, likely to increase as well. Here, we discuss the TS technique, review existing series of iASD with regard to incidence and clinical significance of residual iASD, and present emerging techniques utilizing TS access where iASD may result.

METHODS AND RESULTS

A PubMed search for "iatrogenic atrial septal defects" was performed to identify prospective series addressing the incidence of iASDs after TS procedures. We identified 10 series with primary attention to iASD. Cases involving TS access included electrophysiology ablation procedures, atrial appendage closure, and percutaneous balloon mitral valvuloplasty. Immediate postprocedural incidence of iASD was as high as 87%, with decreased incidence of residual iASD detected over time. At 18 months of follow-up, up to 15% of iASD cases persisted. Residual iASDs were not associated with clinical sequelae of embolism, cyanosis, or right heart failure.

CONCLUSIONS

iASDs are frequent following TS access and a majority resolve over time. Available evidence suggests iASDs are well tolerated but late term follow-up is limited. With the increased utilization of TS transcatheter procedures, the frequency and size of iASDs may rise. Understanding the rare but serious clinical implications of iASD and the need for systematic surveillance in the future is warranted.

Multidetector CT of left atrium

MDCT angiography has enabled visualization of left atrium in addition to coronary arteries. CT images can be utilized to demonstrate normal anatomy and pathologies. Left atrium variations and pathologies include atrial septal pouch, patent foramen ovale, atrial septal defect, atrial band, lipomatous hypertrophy, cor triatriatum, diverticulum, accessory appendages, atrial thrombus and masses. Left atrium should be carefully evaluated in patients undergoing coronary CT angiography. MDCT is becoming an alternative modality for the evaluation of left atrium.