Imaging of the right heart--CT and CMR

Multimodality Imaging to Understand Mechanisms of Right Ventricular Disease

Right ventricular (RV) disease is commonly encountered in patients with cardiovascular conditions and is associated with adverse prognosis. The principal pathogenic mechanisms giving rise to RV pathology include RV pressure overload, RV volume overload, and RV myocardial diseases. Noninvasive cardiac imaging is commonly used to detect the conditions associated with RV disease and ultimately guide therapeutic decisions. Transthoracic echocardiogram is usually the first-line test in patients with suspected RV disease and it provides relevant information on biventricular size and function, valvular abnormalities, and cardiac hemodynamics including pulmonary pressures. Cardiac magnetic resonance imaging is considered the reference standard noninvasive imaging test for quantifying ventricular size and function and cardiac shunts and has a secondary role for assessing valvular disease when echocardiography is nondiagnostic. Cardiac magnetic resonance imaging also provides insight into RV myocardial diseases such as inflammation, infarction, and infiltration. Nuclear cardiology and cardiac computed tomography imaging can also be used to inform on specific RV disease mechanisms originating from lung disease and pulmonary vasculature disorders. In this review, we discuss the role and utility of cardiac imaging in characterizing RV mechanisms of disease and provide a suggested framework for clinicians to appropriately utilize imaging in these clinical scenarios.

Advanced imaging for pre- and post-operative evaluation of tetralogy of Fallot

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease and imaging plays a key role in diagnosis, pre-operative planning and follow up, with MRI as the gold standard for imaging in these patients despite echocardiography being more widely available. While static MRI sequences are suitable for evaluation of anatomical structures, dynamic imaging is required for volume and flow measurements through valves, chambers, and surgical conduits. Newer techniques with 4D data acquisitions allow for feasible 2D cine reconstruction in desired planes. Ferumoxytol, a blood pool contrast agent with long intravascular half-life, facilitates acquisition of 4D flow and 4D MUSIC (multiphase, steady-state imaging with contrast) sequences, eliminating need for repeated contrast administrations. In this article we review conglomerate of TOF anomalies, their historical and current surgical managements with respective devices, as well as cutting-edge MRI techniques for their evaluation.

Multimodality Imaging for Transcatheter Tricuspid Regurgitation Interventions: Novel Approaches to the Forgotten Valve

Tricuspid regurgitation (TR) poses a significant healthcare burden and is a major concern for patients who experience debilitating symptoms and face a poorer prognosis. Cardiologists are showing renewed interest in TR, as the previous belief that it was merely a bystander of left-sided heart disease has evolved. As a result, more transcatheter techniques addressing TR are emerging. Although a clear impact on mortality from these transcatheter tricuspid valve interventions (TTVI) has not yet been demonstrated, the improvement in symptoms and quality of life for patients is substantial, leading to increased use of these procedures in clinical practice. In this review, we focus on multimodality imaging as an essential tool for quantifying TR severity, assessing right ventricular (RV) function, understanding the underlying mechanisms, selecting the appropriate intervention, and ensuring thorough and accurate preprocedural planning to minimize complications.

Multimodality Imaging for Right Ventricular Function Assessment in Severe Tricuspid Regurgitation

Severe tricuspid regurgitation (TR) is a pathological condition associated with worse cardiovascular outcomes. In the vicious cycle of right ventricular compensation and maladaptation to TR, the development of right ventricle (RV) dysfunction has significant prognostic implications, especially in patients undergoing surgical or percutaneous treatments. Indeed, RV dysfunction is associated with increased operative morbidity and mortality in both surgical and percutaneously treated patients. In this context, the identification of clinical or subtle right ventricle dysfunction plays a critical role inpatient selection and timing of surgical or percutaneous tricuspid valve intervention. However, in the presence of severe TR, evaluation of RV function is challenging, given the increase in preload that may lead to an overestimation of systolic function for the Frank-Starling law, reduced reliability of pulmonary artery pressure estimation, the sensitivity of RV to afterload that may result in afterload mismatch after treatment. Consequently, conventional echocardiographic indices have some limitations, and the use of speckle tracking for right ventricular free wall longitudinal strain (RV-FWLS) analysis and the use of 3D echocardiography for RV volumes and ejection fraction estimation are showing promising data. Cardiac magnetic resonance (CMR) represents the gold standards for volumes and ejection fraction evaluation and may add further prognostic information. Finally, cardiac computer tomography (CCT) provides measurements of RV and annulus dimensions that are particularly useful in the transcatheter field. Identification of subtle RV dysfunction may need, therefore, more than one imaging technique, which will lead to tip the balance between medical therapy and early intervention towards the latter before disease progression. Therefore, the aim of this review is to describe the main imaging techniques, providing a comprehensive assessment of their role in RV function evaluation in the presence of severe TR.

Statistical shape modeling of multi-organ anatomies with shared boundaries

Introduction: Statistical shape modeling (SSM) is a valuable and powerful tool to generate a detailed representation of complex anatomy that enables quantitative analysis of shapes and their variations. SSM applies mathematics, statistics, and computing to parse the shape into some quantitative representation (such as correspondence points or landmarks) which can be used to study the covariance patterns of the shapes and answer various questions about the anatomical variations across the population. Complex anatomical structures have many diverse parts with varying interactions or intricate architecture. For example, the heart is a four-chambered organ with several shared boundaries between chambers. Subtle shape changes within the shared boundaries of the heart can indicate potential pathologic changes such as right ventricular overload. Early detection and robust quantification could provide insight into ideal treatment techniques and intervention timing. However, existing SSM methods do not explicitly handle shared boundaries which aid in a better understanding of the anatomy of interest. If shared boundaries are not explicitly modeled, it restricts the capability of the shape model to identify the pathological shape changes occurring at the shared boundary. Hence, this paper presents a general and flexible data-driven approach for building statistical shape models of multi-organ anatomies with shared boundaries that explicitly model contact surfaces. Methods: This work focuses on particle-based shape modeling (PSM), a state-of-art SSM approach for building shape models by optimizing the position of correspondence particles. The proposed PSM strategy for handling shared boundaries entails (a) detecting and extracting the shared boundary surface and contour (outline of the surface mesh/isoline) of the meshes of the two organs, (b) followed by a formulation for a correspondence-based optimization algorithm to build a multi-organ anatomy statistical shape model that captures morphological and alignment changes of individual organs and their shared boundary surfaces throughout the population. Results: We demonstrate the shared boundary pipeline using a toy dataset of parameterized shapes and a clinical dataset of the biventricular heart models. The shared boundary model for the cardiac biventricular data achieves consistent parameterization of the shared surface (interventricular septum) and identifies the curvature of the interventricular septum as pathological shape differences.

Multimodality Imaging of the Neglected Valve: Role of Echocardiography, Cardiac Magnetic Resonance and Cardiac Computed Tomography in Pulmonary Stenosis and Regurgitation

The pulmonary valve (PV) is the least imaged among the heart valves. However, pulmonary regurgitation (PR) and pulmonary stenosis (PS) can occur in a variety of patients ranging from fetuses, newborns (e.g., tetralogy of Fallot) to adults (e.g., endocarditis, carcinoid syndrome, complications of operated tetralogy of Fallot). Due to their complexity, PR and PS are studied using multimodality imaging to assess their mechanism, severity, and hemodynamic consequences. Multimodality imaging is crucial to plan the correct management and to follow up patients with pulmonary valvulopathy. Echocardiography remains the first line methodology to assess patients with PR and PS, but the information obtained with this technique are often integrated with cardiac magnetic resonance (CMR) and computed tomography (CT). This state-of-the-art review aims to provide an updated overview of the usefulness, strengths, and limits of multimodality imaging in patients with PR and PS.

Accordion sign in COVID 19 related acute myocarditis, an old sign for a novel context? A cardiac magnetic resonance case series report study

INTRODUCTION

The COVID-19 pandemic is related to a higher incidence of myocarditis; we present a case series of seven patients, admitted with COVID-19 related acute myocarditis, evaluated with cardiac magnetic resonance imaging, showing an altered profile of the free wall of the right ventricle, no longer present after six months follow-up.

MATERIALS AND METHODS

Seven patients have been evaluated for COVID-19 related acute myocarditis, all patients have been evaluated with cardiac magnetic resonance imaging both in the acute setting and after six months follow-up.

RESULTS

In the acute phase, myocarditis was confirmed in keeping with the current diagnostic criteria. In five out of seven cases, the presence of a crinkling profile of the free wall of the right ventricle was observed; at six months follow up, remission in four out of the five cases and a significant reduction in the remaining case, of the previously described findings, was observed.

CONCLUSIONS

Crinkling appearance in the profile of the free wall of the right ventricle, detectable with cardiac magnetic resonance imaging, might represent a morphological feature present in the acute setting of COVID-19 related myocarditis; several underlying physiopathological mechanisms are conceivable. Further studies are needed to confirm this correlation, define the underlying mechanisms and the prognostic implication related to it. This is the first report in the literature that has considered such findings to the best of our knowledge.

All Roads Lead to Rome: Diverse Etiologies of Tricuspid Regurgitation Create a Predictable Constellation of Right Ventricular Shape Changes

Introduction: Myriad disorders cause right ventricular (RV) dilation and lead to tricuspid regurgitation (TR). Because the thin-walled, flexible RV is mechanically coupled to the pulmonary circulation and the left ventricular septum, it distorts with any disturbance in the cardiopulmonary system. TR, therefore, can result from pulmonary hypertension, left heart failure, or intrinsic RV dysfunction; but once it occurs, TR initiates a cycle of worsening RV volume overload, potentially progressing to right heart failure. Characteristic three-dimensional RV shape-changes from this process, and changes particular to individual TR causes, have not been defined in detail. Methods: Cardiac MRI was obtained in 6 healthy volunteers, 41 patients with ≥ moderate TR, and 31 control patients with cardiac disease without TR. The mean shape of each group was constructed using a three-dimensional statistical shape model via the particle-based shape modeling approach. Changes in shape were examined across pulmonary hypertension and congestive heart failure subgroups using principal component analysis (PCA). A logistic regression approach based on these PCA modes identified patients with TR using RV shape alone. Results: Mean RV shape in patients with TR exhibited free wall bulging, narrowing of the base, and blunting of the RV apex compared to controls (p < 0.05). Using four primary PCA modes, a logistic regression algorithm identified patients with TR correctly with 82% recall and 87% precision. In patients with pulmonary hypertension without TR, RV shape was narrower and more streamlined than in healthy volunteers. However, in RVs with TR and pulmonary hypertension, overall RV shape continued to demonstrate the free wall bulging characteristic of TR. In the subgroup of patients with congestive heart failure without TR, this intermediate state of RV muscular hypertrophy was not present. Conclusion: The multiple causes of TR examined in this study changed RV shape in similar ways. Logistic regression classification based on these shape changes reliably identified patients with TR regardless of etiology. Furthermore, pulmonary hypertension without TR had unique shape features, described here as the "well compensated" RV. These results suggest shape modeling as a promising tool for defining severity of RV disease and risk of decompensation, particularly in patients with pulmonary hypertension.

Multimodality Imaging of the Anatomy of Tricuspid Valve

Even though the tricuspid valve is no longer “forgotten”, it still remains poorly understood. In this review, we focus on some controversial and still unclear aspects of tricuspid anatomy as illustrated by noninvasive imaging techniques. In particular, we discuss the anatomical architecture of the so-called tricuspid annulus with its two components (i.e., the mural and the septal annulus), emphasizing the absence of any fibrous “ring” around the right atrioventricular junction. Then we discussed the extreme variability in number and size of leaflets (from two to six), highlighting the peculiarities of the septal leaflet as part of the septal atrioventricular junction (crux cordis). Finally, we describe the similarities and differences between the tricuspid and mitral valve, suggesting a novel terminology for tricuspid leaflets.

Diagnosis and Management of Failed Surgical Tricuspid Valve Annuloplasty

PURPOSE OF THE REVIEW

Annular-based strategies for treating tricuspid valve (TV) regurgitation do not always have satisfactory long-term outcomes. Management of failed TV annuloplasty can be challenging and requires a dedicated heart team approach. This review explores the treatment options available for failed TV annuloplasty.

RECENT FINDINGS

Recent developments and novel percutaneous treatment options have emerged as promising alternatives for patients with failed TV annuloplasty. Leaflet-based interventions, valve-in-valve procedures, transcatheter tricuspid valves and new-generation trans-caval valves are all feasible options, which can assure good results whilst minimizing risks for the patient. Failure of tricuspid annuloplasty is not uncommon amongst patients treated with either a tricuspid ring or suture-based device. The complex anatomy, physiology and clinical risk profile should be carefully evaluated on an individual patient-by-patient basis in order to select the most appropriate clinical and percutaneous treatment strategy. Different transcatheter tricuspid valve repair or replacement techniques may provide an attractive alternative treatment option for managing this challenging patient cohort.

Tetralogy of Fallot: cardiac imaging evaluation

Thanks to advances in pediatric cardiology, most infants with tetralogy of Fallot (TOF) now survive into adulthood. This relatively new population of adult patients may face long-term complications, including pulmonary regurgitation (PR), right ventricular (RV) tract obstruction, residual shunts, RV dysfunction, and arrythmias. They will often need to undergo pulmonary valve (PV) replacement and other invasive re-interventions. However, the optimal timing for these procedures is challenging, largely due to the complexity of evaluating RV volume and function. The options for the follow-up of these patients have rapidly evolved from an angiography-based approach to the surge of advanced imaging techniques, mainly echocardiography, cardiac magnetic resonance (CMR), and computer tomography (CT). In this review, we outline the indications, strengths and limitations of these modalities in the adult TOF population.

Imaging Needs in Novel Transcatheter Tricuspid Valve Interventions

The advent of novel transcatheter therapies for severe tricuspid regurgitation (TR) has attracted much attention. Novel 3-dimensional imaging techniques have permitted analysis of the tricuspid valve (TV) anatomy from unparalleled views and better understanding of the underlying pathophysiology of TR. Grading TR and assessment of right ventricular function remain challenging, and although 2-dimensional echocardiography is the mainstay imaging technique to evaluate patients with severe TR the use of 3-dimensional echocardiography and cardiovascular magnetic resonance is increasing. The number of transcatheter interventions for TR is growing, and procedural success relies significantly on the pre-procedural evaluation of the anatomy of the TV, etiology and severity of TR, right ventricular size and function, and importantly, the anatomic relationships of the TV. The role of multimodality imaging in patient selection and procedural planning for transcatheter TV repair is reviewed.

Multimodality Imaging of the Right Ventricle

OPINION STATEMENT

Right ventricular (RV) structure and function is clinically important in a wide range of conditions. While conventional echocardiography (echo) methods are widely used, its limitations in RV assessment due its complex geometry are well recognized. New applications of traditional echo methods as well as emerging echo techniques including 3-dimensional (3D) echo and speckle tracking strain have the potential to overcome limitations of conventional echo, though widespread clinical use remains to be seen. Volumetric methods using cardiac magnetic resonance (CMR) and computed tomography (CT) provide accurate assessment of RV function without geometric assumptions. In addition, tissue characterization imaging for myocardial scar and fat using CMR and CT provides important information regarding the RV beyond structure and function alone and has clinical applications for diagnosis and prognosis in a broad range of pathologies. Limitations also exist for these two advanced modalities including availability and patient suitability for CMR and need for contrast and radiation exposure for CT. The complementary role of each modality for the RV as well as emerging evidence for the use of each imaging method in diagnosis and management of RV pathologies is outlined in this study.

2D Echocardiographic Evaluation of Right Ventricular Function Correlates With 3D Volumetric Models in Cardiac Surgery Patients

OBJECTIVES

The early diagnosis and treatment of right ventricular (RV) dysfunction are of critical importance in cardiac surgery patients and impact clinical outcome. Two-dimensional (2D) transesophageal echocardiography (TEE) can be used to evaluate RV function using surrogate parameters due to complex RV geometry. The aim of this study was to evaluate whether the commonly used visual evaluation of RV function and size using 2D TEE correlated with the calculated three-dimensional (3D) volumetric models of RV function.

DESIGN AND SETTING

Retrospective study, single center, University Hospital.

PARTICIPANTS AND INTERVENTION

Seventy complete datasets were studied consisting of 2D 4-chamber view loops (2-3 beats) and the corresponding 4-chamber view 3D full-volume loop of the right ventricle. RV function and RV size of the 2D loops then were assessed retrospectively purely qualitatively individually by 4 clinician echocardiographers certified in perioperative TEE. Corresponding 3D volumetric models calculating RV ejection fraction and RV end-diastolic volumes then were established and compared with the 2D assessments.

MEASUREMENTS AND MAIN RESULTS

2D assessment of RV function correlated with 3D volumetric calculations (Spearman's rho -0.5; p<0.0001). No correlation could be established between 2D estimates of RV size and actual 3D volumetric end-diastolic volumes (Spearman's rho 0.15; p = 0.25).

CONCLUSION

The 2D assessment of right ventricular function based on visual estimation as frequently used in clinical practice appeared to be a reliable method of RV functional evaluation. However, 2D assessment of RV size seemed unreliable and should be used with caution.

An unusual mass of tricuspid valve in an adult patient: blood-filled cyst

Blood-filled cysts (BFC) within the heart are common findings at postmortem examinations of fetuses and infants. However, such cysts are very rare entities in adolescents and adults. We report here an adult case of BFC attached to the posterior leaflet of the tricuspid valve, demonstrating the importance of multimodal diagnostic imaging combining both echocardiography and magnetic resonance imaging.