Tricuspid valve remodelling in functional tricuspid regurgitation: multidetector row computed tomography insights

New therapeutic approach for tricuspid regurgitation: Transcatheter tricuspid valve replacement or repair

The tricuspid valve is a complex structure with normal function dependent on the leaflet morphology, right atrial and annular dynamics, and right ventricular and chordal support. Thus, the pathophysiology of tricuspid regurgitation (TR) is equally complex and current medical and surgical management options are limited. Transcatheter devices are currently being investigated as possible treatment options with lower morbidity and mortality than open surgical procedures. These devices can be divided by their implant location/mechanism of action: leaflet approximation devices, annuloplasty devices, orthotopic valve implants, and heterotopic valve implants. The current review will discuss each class of transcatheter device therapy, and further delve into the current understanding of who and when to treat. Finally, we will include a brief discussion of the future of device and surgical therapy trials for TR and the remaining questions to answer about this complex disease process.

Morphological and Dynamic Analysis of the Right Atrioventricular Junction in Healthy Subjects with 4D Computed Tomography

PURPOSE

To improve knowledge of the tricuspid valve and right atrioventricular junction (RAVJ) coupling, four-dimensional (4D) imaging is mandatory (3D + time). Based on multiphase cardiac-volume computed tomography (CT) and innovative 4D analysis, we proposed to assess dynamical features of tricuspid annulus (TA) in relation to the right ventricle (RV) and right atrial (RA) functions.

METHODS

Cardiac-volume CT data sets through time were obtained in 30 healthy patients (Male 57%, mean age 57 ± 11 years). Using an in-house software, 3D semi-automated delineation of 18 points around TA perimeter were defined through 10 cardiac phases within RR interval and used to calculate TA features such as 3D/2D areas, perimeters, 360°-diameters and vertical deformation. RV and RA inner contours were also delineated. Bi-dimensional parameters were compared with multiplanar reconstruction (MPR) measurements.

RESULTS

TA was elliptical in horizontal projection with a maximal eccentricity index (EcI_max) of 0.58 ± 0.12; and saddle-shaped in vertical projection with a horn nearby the antero-septal commissure. This feature remained throughout the cardiac cycle, but TA was more planar and less circular in late diastole (TA-height: 4.53 ± 1.06 mm, EcI_max = 0.61 ± 0.14) when TA 3D area and perimeter reached a maximum of 7.05 ± 1.23 and 7.48 ± 0.93cm/m², respectively. Correlations between minimal and maximal TA 3D areas and TA Projected 2D areas were excellent (r = 0.993 and r = 0.995, p < 0.001). TA 2D area measurements by MPR overestimated the projected values by 22 to 24%. Correlation between RV concentric strain and TA maximal diameter shortening was r = 0.452 (p = 0.01).

CONCLUSIONS

Cardiac-volume CT improves physiological knowledge of the relationships between the RAVJ components in healthy subjects.

Atrial Mitral and Tricuspid Regurgitation: Sex Matters. A Call for Action to Unravel the Differences Between Women and Men

Atrial functional regurgitation is caused by atrioventricular annulus dilation, with normal leaflets and ventricular dimensions and function within the normal range. Its occurrence, in both mitral and tricuspid valves, implies a worse prognosis due to the hemodynamic derangement they produce, but also constitutes a marker of greater comorbidity and more advanced disease. Predisposing conditions for these heart valve dysfunctions are mainly atrial fibrillation and heart failure with preserved ejection fraction. However, other factors like female sex also may be involved and influence their incidence, especially for atrial tricuspid regurgitation. In the present review, we analyze sex differences in the reported prevalence of atrial mitral and tricuspid regurgitation, and suggest possible mechanisms involved. Finally, we underline potential therapeutic and preventive strategies to reduce the burden of these heart valve disorders and discuss research gaps.

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 Tricuspid Valve Therapy: From Anatomy to Intervention

Nowadays, severe symptomatic tricuspid regurgitation (TR) affects millions of persons worldwide. However, the benefit of surgical correction of isolated secondary TR remains controversial because of the increased risk of periprocedural mortality and morbidity. In recent years, novel transcatheter tricuspid valve interventions (TTVI) were developed to treat TR, so that TTVI is currently considered in symptomatic, inoperable, anatomically eligible patients. TTVI can be divided into these five domains: edge-to-edge leaflet repair, tricuspid annuloplasty, caval implants, spacer, and total valve replacement. Each transcatheter intervention needs specific imaging protocols for assessing the anatomical feasibility and consequentially predicting the procedural success. This review summarizes the available multimodality imaging tools for screening patients with TR, and identifies anatomical characteristics to choose the best option for the patient.

Mitral Valve Annulus Dimensions Assessment with Three-Dimensional Echocardiography Versus Computed Tomography: Implications for Transcatheter Interventions

The aim of this study is to evaluate the agreement between three-dimensional (3D) transesophageal echocardiography (TEE) and multidetector computed tomography (MDCT) for assessing mitral annular (MA) dimensions. A total of 105 patients (79 ± 9 years old, 52% male) who underwent clinically indicated 3D TEE and MDCT feasible for MA geometrical assessment were included. Using dedicated semi-automated postprocessing software, MA geometry, including mitral annular area (MAA), perimeter, septal-lateral (SL) diameter, and inter-trigonal (TT) diameter, was evaluated using 3D TEE and MDCT. Compared to 3D TEE, MAA, perimeter, and SL distance measured on MDCT data were larger (9.9 ± 3.0 vs. 9.3 ± 3.1 cm² for MAA; 115 ± 18 vs. 108 ± 18 mm for perimeter; and 35 ± 5 vs. 32 ± 5 cm for SL distance, all p < 0.001). By contrast, the TT distance was comparable between MDCT and 3D TEE (26 ± 4 vs. 26 ± 4 cm, p = 0.258). The correlations of all the MA dimensions were good to excellent between the two modalities (R = 0.911 for MAA, 0.890 for perimeter, 0.739 for TT distance, and 0.857 for SL distance, respectively, all p < 0.001). This study showed good agreement between 3D TEE- and MDCT-derived MA measurements although MDCT systematically provided larger MAA, perimeter, and SL distance compared with 3D TEE.

Cardiac CT angiography: normal and pathological anatomical features-a narrative review

The normal and pathological anatomy of the heart and coronary arteries are nowadays widely developed topics and constitute a fundamental part of the cultural background of the radiologist. The introduction of cardiac ECG-gated synchronized CT scanners with an ever-increasing number of detectors and with increasingly high structural characteristics (increase in temporal resolution, increase in contrast resolution with dual-source, dual energy scanners) allows the virtual measurement of anatomical in vivo structures complying with heart rate with submillimetric precision permitting to clearly depict the normal anatomy and follow the pathologic temporal evolution. Accordingly to these considerations, cardiac computed tomography angiography (CCTA) asserts itself as a gold standard method for the anatomical evaluation of the heart and permits to evaluate, verify, measure and characterize structural pathological alterations of both congenital and acquired degenerative diseases. Accordingly, CCTA is increasingly used as a prognostic model capable of modifying the outcome of diseased patients in planning interventions and in the post-surgical/interventional follow-up. The profound knowledge of cardiac anatomy and function through highly detailed CCTA analysis is required to perform an efficient and optimal use in real-world clinical practice.

CT support of cardiac structural interventions

Due to its high temporal and isotropic spatial resolution, CT has become firmly established for pre-procedural imaging in the context of structural heart disease interventions. CT allows to very exactly measure dimensions of the target structure, CT can provide information regarding the access route and, as a very valuable addition, volumetric CT data sets can be used to identify fluoroscopic projection angulations to optimally visualize the target structure and place devices. This review provides an overview of current methods and applications of pre-interventional CT to support adult cardiac interventions including transcatheter aortic valve implantation, percutaneous mitral valve intervention, left atrial appendage occlusion and paravalvular leak closure.

Integrated imaging of echocardiography and computed tomography to grade mitral regurgitation severity in patients undergoing transcatheter aortic valve implantation

Aims

Quantitative mitral regurgitation (MR) grading remains challenging. This study evaluated the concept of integrating echocardiography and computed tomography for grading MR severity. Specifically, an integrated parameter was developed that combines the true cross-sectional mitral regurgitant orifice area (ROA) assessed with multi-detector row computed tomography (MDCT) with flow data from echocardiography.

Methods and results

Systolic MDCT data of 73 patients, referred for transcatheter aortic valve implantation (TAVI) who also had MR, were evaluated. The MDCT systolic phase with the smaller left ventricular volume and the largest mitral regurgitant orifice was selected. Using planimetry, the mitral ROA was measured. The mitral ROA was multiplied with the velocity time integral of the MR jet on echocardiography for the calculation of the integrated regurgitant volume (RVol). MDCT analysis showed a mean mitral ROA of 11.3 ± 7.4 mm2 and a mean integrated RVol of 21.4 ± 14.7 mL/beat, whereas echocardiography showed a mean effective ROA and RVol of MR of 13.3 ± 8.2 mm2 and 23.9 ± 13.6 mL/beat, respectively. Compared with echocardiography, grading based on integrated mitral RVol resulted in reclassification of 10% of the patients from severe to non-severe MR and 14% of the patients from non-severe to severe MR.

Conclusions

Integrated mitral RVol is a quantitative parameter of MR severity by combining the true cross-sectional mitral ROA assessed with MDCT and Doppler mitral haemodynamics which resulted in a significant reclassification of MR grade in patients with severe aortic stenosis undergoing TAVR.

Computed tomography for planning transcatheter tricuspid valve therapy

Aims

Percutaneous transcatheter tricuspid valve therapy is an evolving treatment option for patients with significant tricuspid regurgitation (TR) deemed too fragile for open heart surgery. The present study proposes comprehensive anatomical evaluation of the tricuspid valve, right ventricle (RV), and vena cavae and its spatial relationships with the right coronary artery (RCA) using computed tomography (CT) and investigates the implications for suitability for current technologies.

Methods and results

A total of 250 patients (mean age 80 ± 7.2 years, 52.4% men) undergoing CT were divided according to the presence of moderate or severe TR (≥3+, n = 40) and less than moderate TR (<3+, n = 210). Tricuspid valve annulus, RV, and vena cavae dimensions and the course of the RCA relative to the tricuspid annulus were evaluated. Patients with TR ≥ 3+ showed significantly larger dimensions of the tricuspid annulus, RV and vena cavae. In 64.8% of patients, the RCA coursed along the tricuspid valve annulus. Patients with TR <3+ showed more frequently a course of the RCA superior to the tricuspid annulus at the levels of the anterior and the posterior tricuspid leaflet compared with their counterparts (12.4% vs. 0%, P = 0.019). A less favourable course of the RCA (≤2.0 mm distance to the annulus) for current annuloplasty techniques was observed at the level of the anterior tricuspid and posterior leaflets in respective 12.5 and 27.5% of patients with TR ≥3+.

Conclusion

The present study proposes a first systematic approach based on CT to define the patient suitability for current transcatheter tricuspid valve devices.

[Hemodynamic interplay between tricuspid valve and right ventricle]

The tricuspid valve and the right ventricle are hemodynamically closely related. Pathological changes of the valve or of the ventricle itself and also various diseases beyond that can result in a downward spiral of mutual interference, which is of prognostic importance for the patient. The development of a functional tricuspid regurgitation is of great importance. Especially with the help of 3D-echocardiography, more and more changes and mechanisms have been identified that are crucial in this process. This article provides a review of the relationship between the tricuspid valve and the right ventricle emphasizing the current knowledge of the causes, the pathophysiological concepts, the underlying structural changes and the therapeutic approaches based on this.

Revisit of Functional Tricuspid Regurgitation; Current Trends in the Diagnosis and Management

Current knowledge of functional tricuspid regurgitation (FTR) as a progressive entity, worsening the prognosis of patients irrespective of its aetiology, has led to renewed interest in the pathophysiology and assessment of FTR. For the proper management of FTR, not only its severity, but also the mechanisms, the mode of leaflet coaptation, the degree of tricuspid annulus enlargement and leaflet tenting, and the haemodynamic consequences for right atrial and right ventricular morphology and function have to be taken into account. A better assessment of the anatomy and function of tricuspid apparatus and tricuspid regurgitation severity should help with the appropriate selection of patients who will benefit from either surgical tricuspid valve repair/replacement or a percutaneous procedure, especially among patients who are to undergo or have undergone primary left-sided valvular surgery. In this article, we review the anatomy, pathophysiology and the use of imaging techniques to assess patients with FTR, as well as the various treatment options for FTR, including emerging transcatheter procedures. The limitations affecting the current approach to FTR patients and the unmet clinical needs for their management have also been discussed.