Redefinition of tricuspid valve structures for successful ring annuloplasty

Septal annular dilation in chronic ovine functional tricuspid regurgitation

INTRODUCTION

Annular reduction with prosthetic rings represents the current surgical treatment of functional tricuspid regurgitation (FTR). However, alterations of annular geometry and dynamics associated with FTR are not well characterized.

METHODS

FTR was induced in 29 adult sheep with either 8 weeks of pulmonary artery banding (PAB, n = 15) or 3 weeks of tachycardia-induced cardiomyopathy (TIC, n = 14). Eight healthy sheep served as controls (CTL). At the terminal procedure, all animals underwent sternotomy, epicardial echocardiography, and implantation of sonomicrometry crystals on the tricuspid annulus (TA) and right ventricular free wall while on cardiopulmonary bypass. Simultaneous hemodynamic, sonomicrometry, and echocardiographic data were acquired after weaning from cardiopulmonary bypass and stabilization. Annular geometry and dynamics were calculated from 3-dimensional crystal coordinates.

RESULTS

Mean FTR grade (0-4) was 3.2 ± 1.2 and 3.2 ± 0.5 for PAB and TIC, respectively, with both models of FTR associated with similar degree of right ventricular dysfunction (right ventricular fractional area contraction 38 ± 7% and 37 ± 9% for PAB and TIC, respectively). Left ventricular ejection fraction was significantly reduced in TIC versus baseline (33 ± 9%, vs 58 ± 4%, P = .0001). TA area was 651 ± 109 mm2, 881 ± 242 mm2, and 995 ± 232 mm2 for CTL, FTR, and TIC, respectively (P = .006) with TA area contraction of 16.6 ± 4.2%, 11.5 ± 8.0%, and 6.0 ± 4.0%, respectively (P = .003). Septal annulus increased from 33.8 ± 3.1 mm to 39.7 ± 6.4 mm and 43.1 ± 3.2 mm for CTL, PAB, and TIC, respectively (P < .0001).

CONCLUSIONS

Ovine FTR was associated with annular dilation and reduced annular area contraction. Significant dilation of septal annulus was observed in both models of FTR. As tricuspid rings do not completely stabilize the septal annulus, continued remodeling may contribute to recurrent FTR after repair.

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.

Tricuspid Annulus Dilation in Patients With Combined Functional Tricuspid Regurgitation and Left-Heart Valvular Disease: Does Septal Annulus Not Dilate?

Background

This study aimed to investigate the course of tricuspid annulus dilation in functional tricuspid regurgitation with varied severities by direct intraoperative assessment.

Methods

A total of 317 patients who underwent left heart surgery and concomitant tricuspid repair were divided into three groups according to the severity of the functional tricuspid regurgitation (mild, moderate and severe). Demographic and echocardiographic data were collected. The length of each tricuspid annulus segment was measured intraoperatively. The risk factors for preoperative severe functional tricuspid regurgitation and its postoperative recurrence were identified, and the impact of each tricuspid annulus segment on postoperative recurrence was compared.

Results

In the course of tricuspid annulus dilation, the posterior annulus dilated 17% (group 1: 33.31 ± 6.94 mm vs. group 2: 35.56 ± 7.63 vs. group 3: 38.98 ± 8.70, p < 0.01), the anterior annulus dilated 13.4% (group 1: 36.71 ± 6.30 mm vs. group 2: 38.21 ± 8.35 vs. group 3: 41.63 ± 9.20, p < 0.01), and the septal annulus dilated 11.4% (group 1: 38.11 ± 5.28 mm vs. group 2: 39.76 ± 6.90 vs. group 3: 42.46 ± 7.50, p < 0.01). Tricuspid annulus circumference index (p < 0.01) independently correlated with preoperative severe tricuspid regurgitation and postoperative recurrence. When patients were grouped based on the length of each segment, the septal annulus demonstrated significantly higher sensitivity (p < 0.001) to postoperative recurrence than the anterior (p = 0.085) or posterior annulus (p = 0.262).

Conclusions

This study revealed that each segment of tricuspid annulus could dilate in functional tricuspid regurgitation and highlighted the potential benefits of septal annulus plication in tricuspid annuloplasty, which may aid in the development of a methodology for prosthetic ring annuloplasty.

Developing Insights Regarding Tricuspid Valve Regurgitation: Morphology, Assessment of Severity, and the Need for a Novel Grading Scheme

Current understanding that progressive tricuspid regurgitation (TR) is associated with worse outcomes has highlighted the clinical need for a more accurate assessment of TR morphology and severity. This need has been further emphasized owing to the development of a myriad of percutaneous right-sided interventions, which may offer successful treatment of TR in selected patients. Understanding the etiology and quantification of the severity of TR has important implications in the selection of novel therapeutic strategies, i.e., medical vs. percutaneous vs. surgical approaches. Newer grading schemas that better reflect the TR lesion severity have been recently proposed and may facilitate monitoring of the evolution of TR following percutaneous and/or surgical treatment. In this review, we summarize contemporary concepts regarding tricuspid valve morphology, TR etiology, and associated mechanisms and echocardiographic approaches to grade TR severity.

Surgical Correction of Tricuspid Regurgitation

The tricuspid valve is an often forgotten but relevant cause of significant morbidity and mortality. Serious consideration should be given to addressing the valve in patients undergoing left-sided valve surgery who have functional TR, or an enlarged annulus. Tricuspid repair with a ring annuloplasty has shown improved long-term survival and freedom from recurrent TR at as long as 15 years of follow-up compared to suture annuloplasty or other repairs where a prosthetic ring is not used.

Tricuspid leaflet kinematics after annular size reduction in ovine functional tricuspid regurgitation

OBJECTIVE

Tricuspid annular size reduction with annuloplasty rings represents the foundation of surgical repair of functional tricuspid regurgitation. However, the precise effect of annular size reduction on leaflet motion and geometry remains unknown.

METHODS

Ten sheep underwent surgical implantation of a pacemaker with an epicardial lead and were paced 200-240 beats/min to achieve biventricular dysfunction and functional tricuspid regurgitation. Subsequently, sonomicrometry crystals were implanted on the right ventricle, the tricuspid annulus, and on the belly of anterior, posterior, and septal tricuspid leaflets. Double-layer polypropylene suture was placed around the tricuspid annulus and externalized to a tourniquet. Simultaneous echocardiographic, hemodynamic, and sonomicrometry data were acquired with functional tricuspid regurgitation and during 5 consecutive annular reduction steps. Annular area, tenting height, and volume, together with each leaflet strain, radial length, and angles, were calculated from crystal coordinates.

RESULTS

Rapid pacing reduced both left ventricle and right ventricle function and induced functional tricuspid regurgitation (0-3+) in all animals (from 0 ± 0 to 2.4 ± 0.7, P = .002), whereas tricuspid annulus diameter increased from 2.6 ± 0.3 cm to 3.3 ± 0.3 cm (P = .001). Tricuspid annular size reduction 1 to 5 resulted in 16% ± 7%, 37% ± 11%, 55% ± 11%, 66% ± 10%, and 76% ± 8% tricuspid annulus area reduction, respectively, and successively decreased tricuspid regurgitation. Tricuspid annular size reduction 2 to 5 induced anterior and posterior leaflet restricted motion and lower diastolic motion velocities. Tricuspid annular size reduction 5 perturbed septal leaflet range of motion but preserved its angle velocities. Tricuspid annular size reduction 3-5 generated compressive strains in all leaflets.

CONCLUSIONS

Tricuspid annular area reduction of 55% perturbed anterior and posterior leaflet motion while maintaining normal septal leaflet movement. More extreme reduction triggered profound changes in anterior and posterior leaflet motion, suggesting that aggressive undersizing impairs leaflet kinematics.

Animal model considerations to evaluate prosthetic tricuspid valve implants

AIMS

Determining tricuspid valve comparative anatomy and appropriate animal models for preclinical evaluation of prosthetic tricuspid valve implants.

METHODS AND RESULTS

We described and measured 81 heart specimens: 12 humans, 22 dogs, 21 sheep and 26 pigs. Tricuspid annulus circumference varied in humans from 109 to 149 mm, in pigs from 85 to 140 mm, and were ≤125 mm in dogs and sheep. Tricuspid leaflet demarcation in dogs is similar to humans, while in pigs and sheep we observed three distinct leaflets. In humans, sheep and pigs, papillary muscle positions are similar. In dogs they are all based on the septum. A moderator band was observed in all species, but was of consistent thickness only in sheep.

CONCLUSIONS

Sheep and pigs are relevant animal models for evaluating prosthetic tricuspid valve implants. Seventy to 90 kg pigs have a tricuspid annulus size comparable to that in a dilated human heart, but due to possible fast growth leading to sizing incompatibilities, this represents a model for short-term study. Sheep are more stable in size for long term study, however, their tricuspid annulus size is the most similar to that in a healthy, non-dilated human heart. Dogs are not a suitable model due to their significantly different sub-valvular anatomy and smaller size.

Mid-term functional recovery after tricuspid annuloplasty concomitant with left-sided valve surgery

BACKGROUND

To elucidate the impact of tricuspid annuloplasty concomitant with left-sided valve surgery on the right ventricular (RV) function in patients with mild or more tricuspid regurgitation (TR).

METHODS

We enrolled 136 patients with mild or more TR who underwent left-sided valve surgery. Seventy-three patients underwent left-sided valve surgery alone (group non-T) and 63 underwent concomitant tricuspid annuloplasty (group T). The echocardiographic data at the latest follow-up (mean 1019 days) were compared using multiple regression analysis to adjust cofounding factors. Propensity score was calculated and included in the analysis as a covariate. In addition, propensity score matching was used for sensitive analysis (12 pairs).

RESULTS

In group non-T, there were more aortic valve surgeries, and fewer mitral valve surgeries. At baseline, body surface area, New York Heart Association class, and prevalence of atrial fibrillation were significantly different between groups. On preoperative echocardiography, left and right atrial diameter, RV diameter, and tricuspid annular diameter were larger in group T, whereas there was no significant difference in RV fractional area change. In multiple regression analyses, RV diameter in diastole was significantly lower and RV fractional area change was significantly higher at the follow-up period in group T. These results were not attenuated even in subgroup analysis in patients with only mild TR or mitral valve surgery alone.

CONCLUSION

Among patients with mild or more TR, RV dimensional and functional recovery was not obtained with left-sided valve surgery alone. Adding tricuspid annuloplasty may potentially achieve both outcomes.

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

OBJECTIVES

The authors aimed to comprehensively detail the right atrioventricular valve functional leaflet anatomies.

BACKGROUND

The rapid development of both surgical and percutaneous repair techniques for tricuspid regurgitation has renewed interest in variations in the morphology of the right atrioventricular valve.

METHODS

The functioning right atrioventricular valves of 40 reanimated human hearts were imaged using Visible Heart methodologies. Hearts were then perfusion-fixed and dissected, uniquely allowing for the comparative assessments of functional versus fixed valve anatomies from the same set of donor hearts.

RESULTS

The right atrioventricular valves have "3-leaflet" configurations in 57.5% and "4-leaflet" configurations in the remaining hearts. For 4-leaflet valves, extra leaflets were commonly observed in the most inferior regions of the annuli. No difference in valve perimeters between 2 valve types were observed (112.2 vs. 117.1 mm; p = 0.14). In 3-leaflet valves, septal, mural, and superior leaflets occupied 32.2 ± 6.5%, 15.9 ± 5.5%, and 25.5 ± 6.2% of the annulus, respectively, whereas in the 4-leaflet arrangements, these values were 27.0 ± 5.8% (septal), 12.0 ± 4.5% (inferior), 13.7 ± 9.4% (mural), and 19.8 ± 6.1% (superior). The muroseptal/inferoseptal commissures were usually located in the cavotricuspid regions, whereas the inferomural and superomural commissures were in the right atrial appendage vestibule area.

CONCLUSIONS

The right atrioventricular valve has 4 functional leaflets in more than 40% of cases. The authors found that the inferomural region is the most variable area of the valve and believe that anatomic variation is an important consideration for planned interventions.

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.

Transcatheter Tricuspid Valve Interventions: An Emerging Field

PURPOSE OF REVIEW

This review aims to provide an updated overview and a clinical perspective on novel transcatheter tricuspid valve interventions (TTVI), highlighting potential challenges and future directions.

RECENT FINDINGS

Severe tricuspid regurgitation (TR) is a predictor of mortality. However, a sizeable number of patients remain untreated until the end-stage when cardiac surgery presents a prohibitive risk. The emergent need in finding a treatment for patients with TR, deemed for surgery options, has encouraged the development of TTVI. These procedures mimic classical surgery techniques and are mainly divided in four categories: annuloplasty and coaptation devices, edge-to-edge techniques and transcatheter tricuspid valve replacement. Early studies showed promising results, but long-term follow-up data are not available. For patients with severe TR and high surgical risk, several percutaneous options are available. However, these therapies are in a growing phase and bigger studies and long term follow-up are needed to prove their efficacy.

New insight into tricuspid valve anatomy from 100 hearts to reappraise annuloplasty methodology

OBJECTIVE

Prosthetic ring annuloplasty plays an important role in tricuspid valve repair. However, discussions regarding the appropriate suturing technique for rigid annuloplasty rings in patients with tricuspid valve anatomical variations are lacking. We aimed to clarify the diversity and pattern of tricuspid valve morphology.

METHODS

We analyzed tricuspid valve morphology and measured leaflet dimensions in 100 autopsy hearts, which were classified into three groups based on the number of posterior leaflet scallops: single scallop (PLS1) (n = 52), two scallops (PLS2) (n = 42), and three scallops (PLS3) (n = 5). One heart without posterior leaflet was excluded from the statistical analysis. Demographic characteristics were compared between PLS1, PLS2, and PLS3. The linear trends of proportions of each leaflet between PLS1, PLS2, and PLS3 were assessed using linear regression analysis.

RESULTS

Median proportion (interquartile range) of the posterior annular length out of the entire annular perimeter in PLS1, PLS2, and PLS3 was 26% (22-31%), 37% (33-40%), and 45% (42-49%), respectively. Linear regression analysis showed a significant increasing trend (p for trend < 0.001) of the posterior leaflet annulus proportion from PLS1 to PLS3. Accordingly, the anterior and septal annulus proportions significantly decreased from PLS1 to PLS3.

CONCLUSIONS

Approximately half of the tricuspid valve has multiple posterior leaflet scallops. The proportion of the posterior leaflet annular length to the tricuspid valve annulus perimeter increases as the number of posterior leaflet scallops increases. These morphologic variations will be fundamental for future discussion about the pathology of a dilated tricuspid valve and methodology of prosthetic ring annuloplasty.

Tricuspid Valve Annular Mechanics: Interactions with and Implications for Transcatheter Devices

In the interventional treatment of tricuspid valve regurgitation, the majority of prosthetic devices interact with or are implanted to the tricuspid valve annulus. For new transcatheter technologies, there exists a growing body of clinical experience, literature, and professional discourse related to the difficulties in delivering, securing, and sustaining the function of these devices within the dynamic tricuspid annulus. Many of the difficulties arise from circumstances not encountered in open-heart surgery, namely; a non-arrested heart, indirect visualization, and a reliance on non-suture-based methods. These challenges require the application of procedural techniques or system designs to account for tricuspid annular motion, forces, and underlying tissue strength. Improved knowledge in these interactions will support the goals of improving device systems, their procedures, and patient outcomes. This review aims to describe current concepts of tricuspid annular mechanics, key device and procedural implications, and highlight current knowledge gaps for future consideration.

Impact of tricuspid annular size reduction on right ventricular function, geometry and strain

OBJECTIVES

Restrictive tricuspid annuloplasty is a clinically accepted approach to treat functional tricuspid regurgitation. We set out to investigate the effect of varying degrees of tricuspid annular reduction on the right ventricular (RV) function, geometry and strain.

METHODS

Eight, healthy sheep (45 ± 4 kg) had 6 sonomicrometry crystals implanted around the tricuspid annulus and 20 onto the epicardium of the right ventricle defining 3 free wall regions: basal, mid and lower. A polypropylene annuloplasty suture was placed around the tricuspid annulus and externalized to an epicardial tourniquet. Simultaneous echocardiographic, haemodynamic and sonomicrometry data were acquired at baseline and during 5 consecutive annular reduction steps (TAR 1-5) with successive (5-7 mm) suture cinching. RV free wall circumferential, longitudinal and areal cardiac and interventional strains, RV radius of curvature (ROC), cross-sectional area and tricuspid annular dimensions were calculated from 3-dimensional crystal coordinates.

RESULTS

TAR 1-5 resulted in 19 ± 15%, 35 ± 15%, 51 ± 15%, 60 ± 15% and 68 ± 13% tricuspid annular area reduction, respectively. TAR 1 and 2 had minimal influence on the RV function, RV-ROC and strains. TAR 4 and 5 decreased RV-ROC in basal and mid-regions, but reduced the RV cross-sectional area change (from 19 ± 4% at baseline to 14 ± 3% and 13 ± 2%, respectively, P < 0.001) and circumferential and areal strains. TAR 3 significantly decreased free wall RV-ROC from 44.0 ± 1.5 to 42.6 ± 2.4 mm P < 0.001 at the RV base but maintained the regional ventricular function and strains.

CONCLUSIONS

In healthy ovine hearts, a tricuspid annular area reduction of ∼50% provides optimal conditions for reducing RV-ROC while maintaining regional RV function and strain patterns.