Right Atrioventricular Valve Leaflet Morphology Redefined: Implications for Transcatheter Repair Procedures

Contemporary Approach to Tricuspid Regurgitation: Knowns, Unknowns, and Future Challenges

Severe tricuspid regurgitation (TR) worsens heart failure and is associated with impaired survival. In daily clinical practice, patients are referred late, and tricuspid valve interventions (surgical or transcatheter) are underutilised, which may lead to irreversible right ventricular damage and increases risk. This article addresses the appropriate timing and modality for an intervention (surgical or transcatheter), and its potential benefits on clinical outcomes. Ongoing randomised controlled trials will provide further insights into the efficacy of transcatheter valve interventions compared with medical treatment.

Revisiting the anatomy of the right ventricle in the light of knowledge of its development

Controversies continue regarding several aspects of the anatomy of the morphologically right ventricle. There is disagreement as to whether the ventricle should be assessed in bipartite or tripartite fashion, and the number of leaflets to be found in the tricuspid valve. In particular, there is no agreement as to whether a muscular outlet septum is present in the normally constructed heart, nor how many septal components are to be found during normal development. Resolving these issues is of potential significance to those investigating and treating children with congenitally malformed hearts. With all these issues in mind, we have revisited our own experience in investigating the development and morphology of the normal right ventricle. To assess development, we have examined a large number of datasets, prepared by both standard and episcopic microscopy, from human and murine embryos. In terms of gross anatomy, we have compared dissections of normal autopsied hearts with virtual dissections of datasets prepared using computed tomography. Our developmental and postnatal studies, taken together, confirm that the ventricle is best assessed in tripartite fashion, with the three parts representing its inlet, apical trabecular, and outlet components. The ventricular septum, however, has only muscular and membranous components. The muscular part incorporates a small component derived from the muscularised fused proximal outflow cushions, but this part cannot be distinguished from the much larger part that is incorporated within the free-standing muscular infundibular sleeve. We confirm that the tricuspid valve itself has three components, which are located inferiorly, septally, and antero-superiorly.

Utility of CT and MRI in Tricuspid Valve Interventions

Transcatheter tricuspid valve interventions (TTVIs) comprise a variety of catheter-based interventional techniques for treatment of tricuspid regurgitation (TR) in patients at high surgical risk and those with failed previous surgeries. Several TTVI devices with different mechanisms of action are either currently used or in preclinical evaluation. Echocardiography is the first-line modality for evaluation of tricuspid valve disease that provides information on tricuspid valve morphology, mechanism of TR, and hemodynamics. Cardiac CT and MRI have several advantages for a comprehensive preprocedure evaluation. CT and MRI provide complementary information to that of echocardiography on the mechanism and cause of TR. MRI can quantify the severity of TR using indirect or direct techniques that involve two-dimensional or four-dimensional flow sequences. MRI and CT can also accurately quantify right ventricular volumes and function, which is crucial for timing of intervention. CT provides comprehensive three-dimensional information on the morphology of the valve, annulus, subvalvular apparatus, and adjacent structures. CT is the procedure of choice for evaluation of several device-specific measurements, including tricuspid annulus dimensions, annulus-to-right coronary artery distance, leaflet morphology, coaptation gaps, caval dimensions, and cavoatrial-to-hepatic vein distance. CT allows evaluation of the vascular access as well as optimal procedure fluoroscopic angles and catheter trajectory. Postprocedure CT and MRI are useful in detection of complications such as paravalvular leak, pseudoaneurysm, thrombus, pannus, infective endocarditis, and device migration. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Leaflet Morphology and its Implications for Direct Transcatheter Annuloplasty of Tricuspid Regurgitation

BACKGROUND

Leaflet morphology has been associated with treatment success in edge-to-edge repair of tricuspid regurgitation (TR), but the impact on annuloplasty is unclear.

OBJECTIVES

The authors sought to examine the association of leaflet morphology with efficacy and safety of direct annuloplasty in TR.

METHODS

The authors analyzed patients who underwent catheter-based direct annuloplasty with the Cardioband at 3 centers. Leaflet morphology was assessed according to number and location of leaflets by echocardiography. Patients with simple morphology (2 or 3 leaflets) were compared with complex morphology (>3 leaflets).

RESULTS

The study included 120 patients (median age 80 years) with ≥severe TR. A total of 48.3% of patients had a 3-leaflet morphology, 5% a 2-leaflet morphology, and 46.7% had >3 tricuspid leaflets. Baseline characteristics did not differ relevantly between groups except for a higher incidence of torrential TR grade (50 vs 26.6%) in complex morphologies. Postprocedural improvement of 1 (90.6% vs 92.9%) and 2 (71.9% vs 67.9%) TR grades was not significantly different between groups, but patients with complex morphology had more often residual TR ≥3 at discharge (48.2 vs 26.6%; P = 0.014). This difference did not remain significant (P = 0.112) after adjusting for baseline TR severity, coaptation gap, and nonanterior jet localization. Safety endpoints including complications of the right coronary artery, and technical success did not show significant differences.

CONCLUSIONS

Efficacy and safety of transcatheter direct annuloplasty using Cardioband are not affected by leaflet morphology. Assessment of leaflet morphology should be part of procedural planning in patients with TR and might help to individually tailor repair techniques to patient anatomy.

Tricuspid Valve Geometrical Changes in Patients with Functional Tricuspid Regurgitation: Insights from a CT Scan Analysis Focusing on Commissures

BACKGROUND

Cardiac computed tomography (CT) provides important insights into the geometrical configuration of the tricuspid valve (TV). The purpose of the present study was to assess the geometrical changes of TV in patients with functional tricuspid regurgitation (TR) using novel CT scan parameters and to correlate these findings with echocardiography.

METHODS

This single-center study enrolled 86 patients undergoing cardiac CT and divided them into two groups according to the presence or not of severe TR (43 patients with TR ≥ 3+ and 43 controls). The measurements collected were as follows: TV annulus area and perimeter, septal-lateral and antero-posterior annulus diameters, eccentricity, distance between commissures, segment between the geometrical centroid and commissures, and the angles of commissures.

RESULTS

We found a significant correlation between all annulus measurements and the grade of TR, except in regard to angles. TR ≥ 3+ patients had significantly larger TV annulus area and perimeter, larger septal-lateral, and antero-posterior annulus dimensions, as well as larger commissural distance and centroid-commissural distance. In patients with TR ≥ 3+ and controls, the eccentricity index predicted a circular shape and an oval shape of the annulus, respectively.

CONCLUSIONS

These novel CT variables focusing on commissures increase the anatomical understanding of the TV apparatus and the TV geometrical changes in patients with severe functional TR.

Mitral and tricuspid valve disease: diagnosis and management. Consensus document of the Section on Valvular Heart Disease and the Cardiovascular Imaging, Clinical Cardiology, and Interventional Cardiology Associations of the Spanish Society of Cardiology

The diagnosis and management of mitral and tricuspid valve disease have undergone major changes in the last few years. The expansion of transcatheter interventions and widespread use of new imaging techniques have altered the recommendations for the diagnosis and treatment of these diseases. Because of the exponential growth in the number of publications and clinical trials in this field, there is a strong need for continuous updating of local protocols. The recently published 2021 European Society of Cardiology guidelines for the management of valvular heart disease did not include some of the new data on these new therapies and, moreover, the number of mitral and tricuspid interventions varies widely across Europe. Therefore, all this information must be summarized to facilitate its use in each specific country. Consequently, we present the consensus document of the Section on Valvular Disease, Cardiovascular Imaging, Clinical Cardiology, and Interventional Cardiology Associations of the Spanish Society of Cardiology for the diagnosis and management of mitral and tricuspid valve disease.

Transcatheter tricuspid valve intervention techniques and procedural steps for the treatment of tricuspid regurgitation: a review of the literature

Severe tricuspid regurgitation (TR) is an undertreated common pathology associated with significant morbidity and mortality. Classically, surgical repair or valve replacement were the only therapeutic options and are associated with up to 10% postprocedural mortality. Transcatheter tricuspid valve interventions are a novel and effective therapeutic option for the treatment of significant TR. Several devices have been developed with different mechanisms of action. They are classified as annuloplasty devices, replacement devices, caval valve implantation and coaptation devices. In this review, we provide a step-by-step description of the procedural steps and techniques of every device along with video support.

Computationally Assessed 3D Anatomical Proximities and Spatial Relationships Among the Tricuspid Valve Annulus, Right Coronary Artery, and Triangle of Koch: Implications for Transcatheter Tricuspid Annuloplasty Repair

Background

Transcatheter-based annuloplasty therapies for tricuspid regurgitation have demonstrated significant development over recent years. However, the tricuspid valve and neighboring vasculature and conductive tissue regions can present anatomical and device deployment challenges. This present study investigated the anatomical dimensions and spatial relationships of the cardiac structures essential to percutaneous annuloplasty procedures: the tricuspid annulus (TA), right coronary artery (RCA), and triangle of Koch border region.

Methods

Measurements were derived from computational three-dimensional reconstructions of static magnetic resonance imaging scans of perfusion-fixed human hearts (n = 82) with preserved right-sided heart anatomies. This specimen set included heart samples presenting with prediagnosed atrioventricular valvular regurgitation.

Results

Our anatomical assessments demonstrated that the TA to RCA proximities were intensified with the presence of atrioventricular valvular regurgitation, compared with healthy heart specimens. The minimal distances were frequently located between the lateral and posterior annular points. This annular region corresponds to the RCA distal segments and posterior descending branch origins. Greater portions and incidences of the RCA coursing parallel or inferior to the TA plane were recorded for these diseased hearts. Patient demographic variables (gender, age, and body mass index) were insignificant determinants of change for a majority of our results.

Conclusions

These three-dimensional reconstructions provide insights to guide the development and future iterations of transcatheter tricuspid valve annuloplasty systems with regards to device anchoring, annular geometry, tissue proximities, and implantation considerations.

Novel Computed Tomography Variables for Assessing Tricuspid Valve Morphology: Results from the TRIMA (Tricuspid Regurgitation IMAging) Study

BACKGROUND

Computed tomography (CT) is the recommended imaging technique for defining the anatomical suitability for current transcatheter technologies and planning tricuspid valve (TV) intervention. The aim of the Tricuspid Regurgitation IMAging (TRIMA) study was to assess the geometrical characteristics of the TV complex using novel CT parameters.

METHODS

This prospective, single-center study enrolled 22 consecutive patients with severe tricuspid regurgitation, who underwent a cardiac CT study dedicated to the right chambers. The following variables were obtained: annulus area and perimeter, septal-lateral and antero-posterior diameters, tenting height, and anatomical regurgitant orifice area. Moreover, the following novel annular parameters were assessed: distance between commissures, distance between TV centroid and commissures, and angles between centroid and commissures.

RESULTS

A significant phasic variability during the cardiac cycle existed for all variables except for eccentricity, angles, and distance between the postero-septal and antero-posterior commissure and distance between the centroid and antero-posterior commissure. There was a significant relationship between the TV annulus area and novel annular parameters, except for annular angles. Additionally, novel annular variables were found to predict the annulus area.

CONCLUSIONS

These novel additional variables may provide an initial platform from which the complexity of the TV annular morphology can continue to be better understood for further improving transcatheter therapies.

Transcatheter Leaflet Strategies for Tricuspid Regurgitation TriClip and CLASP

Since the recognition of the impact of significant tricuspid regurgitation on the clinical course and mortality, intensive efforts have been made in identifying and developing individually suitable and catheter-based therapy strategies to offer those often older and multimorbid patients at high surgical risk safe, feasible, and efficacious treatment options with justifiable risk. Up to now, transcatheter edge-to-edge repair with leaflet approximation devices such as TriClip (Abbott, Santa Clara, CA, USA) and PASCAL Implant System (Edwards Lifesciences, Irvine, CA, USA) have been evaluated best and several clinical trials could prove safety, feasibility, and efficacy of said devices leading to their recent CE mark. However, further randomized controlled trial are pending and necessary to evaluate their impact on clinical course and outcome in comparison to established treatment recommendations.

Cardiac Computed Tomography and Magnetic Resonance Imaging of the Tricuspid Valve: Preprocedural Planning and Postprocedural Follow-up

Transcatheter tricuspid valve interventions (TTVIs) are rapidly growing as a less invasive treatment of high surgical risk patients with advanced TR. A comprehensive anatomic and functional assessment of the tricuspid valve and right-sided chambers is essential for candidate selection and procedural planning. Advanced imaging with cardiac computed tomography (CCT) and cardiac magnetic resonance (CMR) can provide accurate anatomic and functional assessment of the tricuspid valve, its apparatus, and the right-sided chambers. In this review, we provide an updated overview of the emerging role of CCT and CMR for TR patient evaluation, TTVI planning, and follow-up.

Anatomy of the Tricuspid Valve and Pathophysiology of Tricuspid Regurgitation

Transcatheter valve interventions have seen a significant increase in the past decade. The combination of improved techniques and available tools provides less invasive options supplementing surgical therapies. The tricuspid valve (TV) apparatus is a complex structure between the right atrium and the right ventricle; it generally consists of 3 leaflets (anterior, posterior, and septal) inserted in the fibrous tricuspid annulus and connected to the papillary muscle via the chordae tendinae. This article reviews TV anatomy, the pathophysiology of tricuspid regurgitation, and multimodality imaging to study TV, as well as provides an overview of transcatheter TV intervention.

Transcatheter treatment for tricuspid valve disease

Approximately 4% of subjects aged 75 years or more have clinically relevant tricuspid regurgitation (TR). Primary TR results from anatomical abnormality of the tricuspid valve apparatus and is observed in only 8-10% of the patients with tricuspid valve disease. Secondary TR is more common and arises as a result of annular dilation caused by right ventricular enlargement and dysfunction as a consequence of pulmonary hypertension, often caused by left-sided heart disease or atrial fibrillation. Irrespective of its aetiology, TR leads to volume overload and increased wall stress, both of which negatively contribute to detrimental remodelling and worsening TR. This vicious circle translates into impaired survival and increased heart failure symptoms in patients with and without reduced left ventricular ejection fraction. Interventions to correct TR are underutilised in daily clinical practice owing to increased surgical risk and late patient presentation. The recently introduced transcatheter tricuspid valve interventions aim to address this unmet need. Dedicated expertise and an interdisciplinary Heart Team evaluation are essential to integrate these new techniques successfully and select patients. The present article proposes a standardised approach to evaluate patients with TR who may be candidates for transcatheter interventions. In addition, a state-of-the-art review of the available transcatheter therapies, the main criteria for patient and device selection, and information concerning the remaining uncertainties are provided.

Transgastric imaging-The key to successful periprocedural TEE guiding for edge-to-edge repair of the tricuspid valve

Intraprocedural transesophageal echocardiography (TEE) guidance plays an essential role in transcatheter repair therapy of the tricuspid valve (TV). So far, several different imaging concepts are in use. We propose an imaging protocol that fully addresses the morphological complexity of the TV and further offers efficacious workarounds for the frequently occurring restrictions of TV imaging in edge-to-edge repair of the TV. As a tertiary referral center with a large experience of more than 250 cases of transcatheter edge-to-edge repair (TEER) of the TV performed at the Heart Valve Center in Mainz/Germany, we have constantly adapted our peri-interventional echocardiographic approach to accomplish both. As a key measure for success, we intensely rely on the transgastric acoustic windows that not only deliver high-resolution information on the morphology of the TV and all relevant procedural steps but also help to avoid the frequent shadowing artifacts experienced in transesophageal imaging.

Leaflet Configuration and Residual Tricuspid Regurgitation After Transcatheter Edge-to-Edge Tricuspid Repair

OBJECTIVES

This study aimed to assess the anatomical leaflet variation and investigate its impact on the procedural outcome in patients undergoing transcatheter edge-to-edge tricuspid repair.

BACKGROUND

Tricuspid regurgitation (TR) is associated with a poor prognosis.

METHODS

The study participants were consecutive patients who underwent transcatheter edge-to-edge tricuspid repair with the MitraClip, TriClip, or PASCAL systems from June 2015 to July 2020 at the Bonn Heart Center. The tricuspid leaflet morphologies were imaged using 2-dimensional and 3-dimensional transesophageal echocardiography. The severity of TR was assessed according to the 5-grade scheme. The primary endpoint was residual TR ≥3+ within 30 days.

RESULTS

Of the 145 study participants, 103 (71.1%) participants were categorized as the 3-leaflet configuration, while 42 (28.9%) were categorized as the 4-leaflet configuration. Successful device implantation was achieved in 136 (93.8%) patients, with no statistical difference between the 3-leaflet and 4-leaflet configuration groups. However, compared with patients with a 3-leaflet configuration, patients with 4-leaflet configuration more frequently had residual TR ≥3+ (18.4% vs 38.1%; P = 0.018). In the multivariable model, the 4-leaflet configuration was associated with an increased risk of residual TR ≥3+ (odds ratio: 2.65; 95% CI 1.15-6.10; P = 0.022), independent of baseline TR grade, coaptation gap width, and TR jet location. After 1-year follow-up, compared with patients with residual TR <3+, patients with residual TR ≥3+ had a significantly higher incidence of the composite of all-cause mortality or heart failure hospitalization (27.7% vs 56.1%; P = 0.016).

CONCLUSIONS

A 4-leaflet configuration of the tricuspid valve is observed in approximately one-third of patients undergoing transcatheter edge-to-edge tricuspid repair, which is associated with an increased risk of residual TR after the procedure.

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.

Transcatheter treatment of severe tricuspid regurgitation

PURPOSE OF REVIEW

Severe tricuspid regurgitation is a commonly prevalent valvular heart disease that is an independent adverse prognostic marker. However, the majority of patients with tricuspid regurgitation are managed medically; isolated tricuspid valve surgery is rarely performed, partly owing to high associated in-hospital mortality. Therefore, several transcatheter tricuspid valve interventions (TTVIs) that have been developed over the last few years to address this unmet clinical need.

RECENT FINDINGS

The early experience with TTVI has shown that most devices can be safely implanted with excellent rates of technical success and acceptable safety outcomes. Most TTVI recipients have significant improvement in tricuspid regurgitation severity, functional class, and quality of life. Recent retrospective data also suggest mortality benefit of TTVI compared with medical management. There are several issues that need to be addressed prior to widespread adoption of TTVI, including more effective tricuspid regurgitation reduction and need for longer term efficacy data.

SUMMARY

TTVI has emerged as an attractive treatment option for management of high-risk patients with tricuspid regurgitation. In this review, we will discuss the anatomical considerations specific to tricuspid valve, patient selection, preprocedure planning, and summarize the current evidence and future perspectives on TTVI.

Mutual Arrangements of Coronary Blood Vessels within the Right Atrial Appendage Vestibule

Background: The aim of our study was to investigate the presence and mutual relationships of coronary vessels within the right atrial appendage (RAA) vestibule. Methods: We examined 200 autopsied hearts. The RAA vestibule was cross-sectioned along its isthmuses (superior, middle, and inferior). Results: The right coronary artery (RCA) was present in 100% of the superior RAA isthmuses but absent in 2.0% of hearts within the middle isthmus and in 6.5% of hearts within the inferior RAA isthmus. Its diameter was quite uniform along the superior (2.6 ± 0.8 mm), middle (2.9 ± 1.1 mm), and inferior (2.7 ± 0.9 mm) isthmuses (p = 0.12). The location of the RCA varied significantly, and it was sometimes accompanied by other accessory coronary vessels. In all the isthmuses, the RCA ran significantly closer to the endocardial surface than to the epicardial surface (p < 0.001). At the superior RAA isthmus, the artery was furthest from the right atrial endocardial surface and this distance gradually decreased between the middle RAA isthmus and the inferior RAA. Conclusions: This study was the most complex analysis of the mutual arrangements and morphometric characteristics of coronary blood vessels within the RAA vestibule. Awareness of additional blood vessels within the vestibule can help clinicians plan and perform safe and efficacious procedures in this region.

Roles of Cardiac Computed Tomography in Guiding Transcatheter Tricuspid Valve Interventions

PURPOSE OF REVIEW

The field of transcatheter tricuspid valve interventions (TTVI) is rapidly evolving to meet a well-defined but unmet clinical need. Severe tricuspid regurgitation is common and is associated with significant morbidity and mortality. Surgical options are limited and of high risk. The success of TTVI depends on careful procedural planning, and cardiac computed tomography (CCT) plays an emerging key role.

RECENT FINDINGS

TTVI technologies have various targets, including the leaflets, annulus, and venae cavae, along with valve replacement. Based on the planned procedure, CCT allows for device sizing, careful assessment of the access route, and comprehensive analysis of relevant adjacent anatomic structures to enhance procedural safety. It can also evaluate right-sided heart function, and its data can be for fusion imaging and 3D printing. Procedural planning is key to TTVI's success and is highly dependent on high-quality CCT data. This review details the comprehensive roles of CCT, specifics of the dedicated TTVI protocol, and its limitations.

Morphology and Position of the Right Atrioventricular Valve in Relation to Right Atrial Structures

The right atrioventricular valve (RAV) is an important anatomical structure that prevents blood backflow from the right ventricle to the right atrium. The complex anatomy of the RAV has lowered the success rate of surgical and transcatheter procedures performed within the area. The aim of this study was to describe the morphology of the RAV and determine its spatial position in relation to selected structures of the right atrium. We examined 200 randomly selected human adult hearts. All leaflets and commissures were identified and measured. The position of the RAV was defined. Notably, 3-leaflet configurations were present in 67.0% of cases, whereas 4-leaflet configurations were present in 33.0%. Septal and mural leaflets were both significantly shorter and higher in 4-leaflet than in 3-leaflet RAVs. Significant domination of the muro-septal commissure in 3-leflet valves was noted. The supero-septal commissure was the most stable point within RAV circumference. In 3-leaflet valves, the muro-septal commissure was placed within the cavo-tricuspid isthmus area in 52.2% of cases, followed by the right atrial appendage vestibule region (20.9%). In 4-leaflet RAVs, the infero-septal commissure was located predominantly in the cavo-tricuspid isthmus area and infero-mural commissure was always located within the right atrial appendage vestibule region. The RAV is a highly variable structure. The supero-septal part of the RAV is the least variable component, whereas the infero-mural is the most variable. The number of detected RAV leaflets significantly influences the relative position of individual valve components in relation to right atrial structures.

Proposal for a Standard Echocardiographic Tricuspid Valve Nomenclature

OBJECTIVES

The purpose of this study was to introduce a novel clinically relevant nomenclature system for the TV and determine the relative incidence of each morphological type.

BACKGROUND

With the rapid development of transcatheter tricuspid valve (TV) repair techniques, there is a growing recognition of the variability in leaflet morphology and a need for a unified nomenclature, which could aid in procedural planning and execution.

METHODS

Patients from 4 medical centers (2 in Europe, 2 in the United States) referred for transesophageal echocardiography (TEE) to assess native TV function, were retrospectively analyzed for leaflet morphology with the use of a novel classification scheme. Four morphological types were identified: type I, 3 leaflets; type II, 2 leaflets; type IIIA, 4 leaflets with 2 anterior; type IIIB, 4 leaflets with 2 posterior; type IIIC, 4 leaflets with 2 septal; and type IV, >4 leaflets.

RESULTS

A total of 579 patients were analyzed: mean age 78.1 ± 8.0 years, 50.4% female, 70.9% in atrial fibrillation, and 32.2% with previous left heart surgery or transcatheter intervention. Tricuspid regurgitation was moderate or less in 9.4%, severe in 40.5%, massive in 32.3%, and torrential in 17.7%. The etiology of tricuspid regurgitation was primary in 9.4%, mixed in 10.8%, and secondary in all of the other patients (18.6% atriogenic/isolated). The incidence of type I morphology was 312 of 579 (53.9%), type II was 26 of 579 (4.5%), type IIIA was 15 of 579 (2.6%), type IIIB was 186 of 579 (32.1%), type IIIC was 22 of 579 (3.8%), and type IV was 14 of 579 (2.4%).

CONCLUSIONS

A novel TV leaflet nomenclature classification scheme can be used to identify 4 types of TV morphologies with the use of TEE imaging. From this multinational retrospective study, the TV has 3 well defined leaflets in only ∼54% of patients and 4 functional leaflets in ∼39% of patients, with type IIIB (2 posterior leaflets) being the most common of the latter. The utility of this classification scheme deserves further study.

Tricuspid Valve Annuloplasty Alters Leaflet Mechanics

Tricuspid valve regurgitation is associated with significant morbidity and mortality. Its most common treatment option, tricuspid valve annuloplasty, is not optimally effective in the long-term. Toward identifying the causes for annuloplasty's ineffectiveness, we have previously investigated the technique's impact on the tricuspid annulus and the right ventricular epicardium. In our current work, we are extending our analysis to the anterior tricuspid valve leaflet. To this end, we adopted our previous strategy of performing DeVega suture annuloplasty as an experimental methodology that allows us to externally control the degree of cinching during annuloplasty. Thus, in ten sheep we successively cinched the annulus and quantified changes to leaflet motion, dynamics, and strain in the beating heart by combining sonomicrometry with our well-established mechanical framework. We found that successive cinching of the valve enforced earlier coaptation and thus reduced leaflet range of motion. Additionally, leaflet angular velocity during opening and closing decreased. Finally, we found that leaflet strains were also reduced. Specifically, radial and areal strains decreased as a function of annular cinching. Our findings are critical as they suggest that suture annuloplasty alters the mechanics of the tricuspid valve leaflets which may disrupt their resident cells' mechanobiological equilibrium. Long-term, such disruption may stimulate tissue maladaptation which could contribute to annuloplasty's sub-optimal effectiveness. Additionally, our data suggest that the extent to which annuloplasty alters leaflet mechanics can be controlled via degree of cinching. Hence, our data may provide direct surgical guidelines.

Topographical anatomy of the right atrial appendage vestibule and its isthmuses

INTRODUCTION

The right atrial appendage (RAA) vestibule is an area located in the right atrium between the RAA orifice and the right atrioventricular valve annulus and may be a target for invasive transcatheter procedures.

METHODS AND RESULTS

We examined 200 autopsied human hearts. Three isthmuses (an inferior, a middle, and a superior isthmus) were detected. The average length of the vestibule was 67.4 ± 10.1 mm. Crevices and diverticula were observed within the vestibule in 15.3% of specimens. The isthmuses had varying heights: superior: 14.0 ± 3.4 mm, middle: 11.2 ± 3.1 mm, and inferior: 10.1 ± 2.7 mm (p < .001). The superior isthmus had the thickest atrial wall (at midlevel: 16.7 ± 5.6 mm), the middle isthmus had the second thickest wall (13.5 ± 4.2 mm), and the inferior isthmus had the thinnest wall (9.3 ± 3.0 mm; p < .001). This same pattern was observed when analyzing the thickness of the adipose layer (superior isthmus had a thickness of 15.4 ± 5.6 mm, middle: 11.7 ± 4.1 mm and inferior: 7.1 ± 3.1 mm; p < .001). The average myocardial thickness did not vary between isthmuses (superior isthmus: 1.3 ± 0.5 mm, middle isthmus: 1.8 ± 0.8 mm, inferior isthmus: 1.6 ± 0.5 mm; p > .05). Within each isthmus, there were variations in the thickness of the entire atrial wall and of the adipose layer. These were thickest near the valve annulus and thinnest near the RAA orifice (p < .001). The thickness of the myocardial layer followed an inverse trend (p < .001).

CONCLUSIONS

This study was the first to describe the detailed topographical anatomy of the RAA vestibule and that of its adjoining isthmuses. The substantial variability in the structure and dimensions of the RAA isthmuses may play a role in planning interventions within this anatomic region.

Intracardiac echocardiography to enable successful edge-to-edge transcatheter tricuspid valve repair in patients with insufficient TEE quality

BACKGROUND

Transesophageal echocardiography (TEE) as a guiding tool for edge-to-edge transcatheter tricuspid valve repair (EETVr) using MitraClip (Abbott Vascular, Santa Clara, USA) may not offer sufficient image quality in a significant proportion of patients.

OBJECTIVES

Intracardiac echocardiography (ICE) as additional guiding tool in EETVr with the MitraClip device.

METHODS

Appropriate angulations of the ICE catheter to visualize each commissure of the tricuspid valve were established in 3D printed heart models. In a single tertiary-care center ICE was used to support EETVr as additional guidance when TEE image quality was insufficient. Procedural safety and outcomes up to 30-days were compared between ICE/TEE and TEE only guided patients.

RESULTS

In 6 of 11 patients (54.5%) undergoing EETVr with MitraClip TEE alone was unsatisfactory, necessitating additional ICE guidance. In 4 of these 6 patients ICE enabled a successful completion of the procedure. The steering maneuvers identified in the 3D models were well applicable in all patients, providing examples for potential future ICE implementation in EETVr. Under both TEE alone (n = 5) and ICE (n = 6) guidance the rate of procedural complications was 0%. According to vena contracta values at discharge significant TR reduction was achievable in the treated cohort (p = 0.011). At 30-days follow-up one patient (ICE guided) died following global heart failure, not associated with the procedure itself.

CONCLUSIONS

ICE guidance may offer an additional tool to guide EETVr with the MitraClip device in patients with poor TEE quality, as it enables successful results without impairing procedural safety.

Unsupervised Mitral Valve Tracking for Disease Detection in Echocardiogram Videos

In this work, a novel algorithmic scheme is developed that processes echocardiogram videos, and tracks the movement of the mitral valve leaflets, and thereby estimates whether the movement is symptomatic of a healthy or diseased heart. This algorithm uses automatic Otsu's thresholding to find a closed boundary around the left atrium, with the basic presumption that it is situated in the bottom right corner of the apical 4 chamber view. A centroid is calculated, and protruding prongs are taken within a 40-degree cone above the centroid, where the mitral valve is located. Binary images are obtained from the videos where the mitral valve leaflets have different pixel values than the cavity of the left atrium. Thus, the points where the prongs touch the valve will show where the mitral valve leaflets are located. The standard deviation of these points is used to calculate closeness of the leaflets. The estimation of the valve movement across subsequent frames is used to determine if the movement is regular, or affected by heart disease. Tests conducted with numerous videos containing both healthy and diseased hearts attest to our method's efficacy, with a key novelty in being fully unsupervised and computationally efficient.

Utility of Three-Dimensional (3D) Modeling for Planning Structural Heart Interventions (with an Emphasis on Valvular Heart Disease)

PURPOSE OF REVIEW

Advanced imaging has played a vital role in the contemporary, rapid rise of structural heart interventions. 3D modeling and printing has emerged as one of the most recent imaging tools and the implementation of 3D modeling is expected to increase with further advances in imaging, print hardware, and materials.

RECENT FINDINGS

3D modeling can be used to educate patients and clinical teams, provide ex vivo procedural simulation, and improve outcomes. Intra-procedural success rates may be improved, and post-procedural complications can be predicted more robustly with appropriate application of 3D modeling. Recent advances in technology have increased the availability of this tool, such that there can be more ready adoption into a routine clinical workflow. Familiarity with 3D modeling and its current utilization and role in structural interventions will help inform how to approach and adapt this exciting new technology.

Imaging and Patient Selection for Transcatheter Tricuspid Valve Interventions

With the emergence of transcatheter solutions for the treatment of tricuspid regurgitation (TR) increased attention has been directed to the once neglected tricuspid valve (TV) complex. Recent studies have highlighted new aspects of valve anatomy and TR etiology. The assessment of valve morphology along with quantification of regurgitation severity and RV function pose several challenges to cardiac imagers guiding transcatheter valve procedures. This review article aims to give an overview over the role of modern imaging modalities during assessment and treatment of the TV.

Percutaneous Treatment of a Four-Leaf Clover Valve Using the MitraClip Technology

Percutaneous treatment of tricuspid valve regurgitation using MitraClip can be performed safely achieving improvement in reduction of regurgitation. Tricuspid valve shows different anatomic variations, in particular regarding the number of leaflets, which could represent a challenge for transcatheter valve intervention. We present a case of massive tricuspid regurgitation in a 4-leaf clover valve. We implanted a first MitraClip into the anteroseptal commissure and then a second one between the 2 posterior leaflets, with a successful reduction of residual regurgitation. In conclusion, this approach can be safely performed in a 4-leaflet right ventricular valve.