The Right Atrium: Gateway to the Heart—Anatomic and Pathologic Imaging Findings

Abstract

Knowledge of right atrial anatomic and pathologic imaging findings and associated clinical symptoms is important to avoid false-positive diagnoses and missed findings. Complete evaluation of the heart often requires a multimodality approach that includes radiography, echocardiography, computed tomography (CT), magnetic resonance (MR) imaging, and invasive angiography. In general, CT provides the highest spatial resolution of these modalities at the cost of radiation exposure to the patient. Echocardiography and MR imaging offer complementary and detailed information for functional evaluation without added radiation exposure. The advantages and disadvantages of each modality for the evaluation of right atrial anatomic structure, size, and pathologic findings are discussed. Cardiac MR imaging is the reference standard for evaluation of right atrial size and volume but often is too time consuming and resource intensive to perform in routine clinical practice. Therefore, established reference ranges for two-dimensional transthoracic echocardiography are often used. Right atrial pathologic findings can be broadly categorized into (a) congenital anomalies (cor triatriatum dexter, Ebstein anomaly, and aneurysm), (b) disorders of volume (tricuspid regurgitation, pathologic mimics such as a pseudoaneurysm, and atrial septal defect), (c) disorders of pressure (tricuspid stenosis, restrictive cardiomyopathy, and constrictive pericarditis), and (d) masses (pseudomasses, thrombus, lipomatous hypertrophy of the interatrial septum, lipoma, myxoma, sarcoma, and metastatic disease). Familiarity with each pathologic entity and its treatment options is essential to ensure that appropriate imaging modalities are selected. Online supplemental material is available for this article.

4D flow MRI assessment of right atrial flow patterns in the normal heart – influence of caval vein arrangement and implications for the patent foramen ovale

“…This is supported by a case we reported, of a subject with platydeoxia orthopnoea, where the orientation of IVC flow appeared to be associated, uniquely, with reversal of the right atrial vortex and substantial shunting across the PFO [23]. We did not find a gross difference in right atrial size or shape, but the morphology of this chamber is complex with no standard approach to volumetric analysis [16]. Further work will be required to detail the contribution of variation in the chamber morphology to vortex evolution.…”

“…Long and short axis dimensions of the right atrium were measured at end systole in the four-chamber cine view to assess right atrial size. The ratio of these dimensions was calculated as a surrogate measure of sphericity [16]. …”

Global left atrial failure in heart failure

“…Based on these considerations, the perturbations of LA size and mechanical function have been evaluated in several recent studies, including patients with heart failure (HF) . In contrast, data on the clinical and prognostic characteristics of right atrial (RA) size and volume are limited because of the paucity of standardized RA volume data by two‐dimensional echocardiography …”

Optimal Cardiac Magnetic Resonance Contrast-Enhanced Timing Robust Angiography (CMR-CENTRA) for the Three-Dimensional Reconstruction of the Bilateral Atria in the Electroanatomic Mapping (EAM) of Atrial Fibrillation

“…The RA receives the inferior and superior vena cava and the orifice of the coronary sinus (15,16). When the contrast media is injected into the cubital vein, it initially enters the RA through the superior vena cava (17).…”

“…When the contrast media is injected into the cubital vein, it initially enters the RA through the superior vena cava (17). Therefore, the initial combination of opacified and non-opacified blood from the systemic veins interrupts the homogenous contrast enhancement in the RA chamber (15,17). In other words, the homogeneous contrast enhancement of the RA can be achieved with the opacified blood drained from both the inferior and superior vena cava.…”