Percutaneous bicaval valve implantation for transcatheter treatment of tricuspid regurgitation: clinical observations and 12-month follow-up

Implantable cardioverter-defibrillator lead failure and revision following transcutaneous bicaval valve (TricValve®) implantation

INTRODUCTION

Tricuspid regurgitation is associated with significant morbidity and mortality, and occurs at a higher rate in patients with cardiovascular implantable electronic devices. Percutaneous strategies for managing tricuspid regurgitation are evolving, including the development of bicaval valve implantation which has been successfully used in patients with pacing leads.

METHODS AND RESULTS

We present the first documented case of lead failure following TricValve® implantation, a dedicated self-expanding system for bicaval valve implantation, and the first successful lead revision procedure in this setting.

CONCLUSION

The case illustrates important considerations in undertaking percutaneous intervention in patients with cardiovascular implantable electronic devices, and their ongoing management.

Current Status of Transcatheter Tricuspid Valve Therapies

Tricuspid regurgitation is a complex disease that carries a poor prognosis, and surgical repair is associated with high mortality. In light of the success of other transcatheter-based valve interventions, transcatheter tricuspid therapy has recently seen exponential use both clinically and in innovation. Given the rapid development of many tricuspid systems and multiple on-going clinical trials, the aim of this review is to highlight the current state of transcatheter tricuspid therapeutics and to provide an up-to-date view of their clinical use, outcomes and future directions.

Renal and hepatic function of patients with severe tricuspid regurgitation undergoing inferior caval valve implantation

Due to progressive abdominal-venous congestion severe tricuspid regurgitation (TR) is a common cause of cardiorenal and cardiohepatic syndrome. We initiated the TRICAVAL study to compare interventional valve implantation into the inferior vena cava (CAVI) versus optimal medical therapy (OMT) in severe TR. In the present subanalysis, we aimed to evaluate the effects of CAVI on clinical signs of congestion, renal and hepatic function. TRICAVAL was an investigator-initiated, randomized trial. Twenty-eight patients with severe TR were randomized to OMT or CAVI using an Edwards Sapien XT valve. Probands who completed the 3-month follow-up (CAVI [n = 8], OMT [n = 10]) were evaluated by medical history, clinical examination, and laboratory testing at baseline, 3 and 12 months. After 3 months, the CAVI group exhibited a significant reduction of body weight (from 80.7 [69.0–87.7] kg to 75.5 [63.8–84.6] kg, p < 0.05) and abdominal circumference (from 101.5 ± 13.8 cm to 96.3 ± 15.4 cm, p ≤ 0.01) and a trend to lower doses of diuretics compared to OMT. Renal and hepatic function parameters did not change significantly. Within a short-term follow-up, CAVI led to an improvement of clinical signs of venous congestion and a non-significant reduction of diuretic doses compared to OMT.

Caval Valve Implantation (CAVI): An Emerging Therapy for Treating Severe Tricuspid Regurgitation

Severe tricuspid regurgitation remains a challenging heart-valve disease to effectively treat with high morbidity and mortality at mid-term. Currently guideline-directed medical treatment is limited to escalating dose of diuretics, and the rationale and timing of open-heart surgery remains controversial. Emerging percutaneous therapies for severe tricuspid regurgitation continue to show promising results in early feasibility studies. However, randomized trial data is lacking. Additionally, many patients are deemed unsuitable for these emerging therapies due to anatomical or imaging constraints. Given the technical simplicity of the bicaval valve implantation (CAVI) technique compared to other transcatheter devices, CAVI is postulated as a suitable alternative for a wide variety of patients affected with severe+ tricuspid regurgitation. In this review we illustrate the current evidence and ongoing uncertainties of CAVI, focusing on the novel CAVI-specific devices.

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.

[Current technologies in interventional treatment of tricuspid valve regurgitation]

For a long time, severe tricuspid valve regurgitation (TR) was an underestimated disease, especially in the older population and was associated with high morbidity and mortality. Due to the high perioperative mortality of tricuspid valve surgery, historically only pharmaceutical treatment was a practical treatment option. In the first studies interventional approaches could achieve promising results with an effective reduction of TR with simultaneous proof of a convincing safety profile. Conceptually, the currently available interventional treatment options can be divided into three concepts: coaptation systems (edge-to-edge repair), annuloplasty and interventional valve replacement. The largest clinical experience and best scientific body of evidence could so far be generated in the field of coaptation systems. Very promising preliminary results with effective reduction of TR and improvement of the clinical symptoms are, however, also available for interventional valve replacement. Meticulous preprocedural diagnostics with selection of the most suitable treatment option for each individual patient is paramount for successful treatment in this critically ill patient cohort. Future prospective randomized studies will investigate the net benefit of an interventional treatment of TR in comparison to a purely conservative treatment concept.

Feasibility of Transcatheter Caval Valve Implantation to Improve -Disordered Breathing in Patients With Severe Tricuspid Regurgitation-A Pilot Study

Transcatheter caval valve implantation (CAVI) has been evaluated as a treatment option for inoperable patients with severe symptomatic tricuspid regurgitation (TR). We studied the effect of CAVI on sleep disorder breathing (SDB) in patients with right heart failure and TR. Twenty right heart failure patients with severe symptomatic TR who underwent portable monitoring of SDB (ApneaLink), echocardiography, cardiopulmonary exercise (CPET), and laboratory testing were enrolled. This was a single-center, nonblinded study. There were no significant changes in sleep variables, echocardiographic parameters, laboratory results, lung function, and CPET after CAVI. In conclusion, these data suggest that CAVI may not have an effect on SDB; however, additional follow-up fully powered studies with appropriate statistical analyses are needed.

Transcatheter Tricuspid Valve Intervention: Current Perspective

Tricuspid regurgitation (TR) adversely impacts both quality of life and long-term survival, which generates interest in therapeutic approaches to mitigate these effects. Historically, therapeutic options for TR were limited to surgical approaches, which are often complicated by significant morbidity and mortality in elderly patients with multiple comorbidities. This gap in therapeutic options led to the rapid evolution of transcatheter tricuspid valve intervention (TTVI), with a wide variety of approaches pursued and early results suggesting that TTVI improves clinical outcomes. Numerous strategies, including edge-to-edge repair, annular reduction, spacers, caval valve implantation, and transcatheter tricuspid valve replacement form the basis of TTVI today. In this review, the authors discuss the current state of each approach.

Update on Transcatheter Tricuspid Valve Replacement Therapies

Severe tricuspid regurgitation is relatively common, especially in the elderly, and portends poor survival. Neither medical therapy nor conventional surgery is efficacious for most patients. In contrast, transcatheter tricuspid valve interventions are showing promise to improve quality of life and mortality. Although there is more clinical experience with transcatheter tricuspid valve repair, there are many patients for which repair is either not possible or cannot optimally reduce the severity of tricuspid regurgitation. Transcatheter tricuspid valve replacement is rapidly emerging and may ultimately become the preferred treatment option. In this review, we discuss transcatheter tricuspid valve replacement, analyze the devices in development and in clinical trials, and highlight the advantages and drawbacks of transcatheter tricuspid valve replacement vs. repair.

Transcatheter Interventions for Tricuspid Valve Disease: What to Do and Who to Do It On

Tricuspid valve disease, and particularly the management of severe tricuspid regurgitation (TR), has gained momentum in recent years. Although it is well known that this frequent condition is associated with poor clinical outcomes, these patients have been classically managed medically, leading to end-stage right ventricular heart failure. Moreover, late referral to surgery has contributed to a high rate of periprocedural complications and in-hospital surgical mortality. Thus, the development of a less invasive catheter-based therapy would be of high clinical relevance in this context. Several transcatheter tricuspid valve intervention (TTVI) devices have been developed in recent years. The particular characteristics of the tricuspid valve (large noncalcific annulus, presence of chief surrounding structures such as the conduction system or the right coronary artery) make multimodality imaging (eg, transesophageal echocardiography, computed tomography) key in the preprocedural assessment of TTVI. According to their mechanism of action and therapeutic target, TTVI includes transcatheter repair either with coaptation or annuloplasty systems, caval valve devices, and transcatheter tricuspid valve replacement. The initial TTVI experience showed that most procedures were well tolerated, with high procedural success and low in-hospital and early mortality. Also, most TTVI recipients improved their functional status and recent data suggest improved outcomes compared with medical management. However, the rate of significant residual TR after transcatheter tricuspid valve repair remains high and very scarce data exist on longer term (beyond 6-12 months) outcomes. The present review provides an overview regarding the framework of chronic TR and TTVI therapeutic options, and describes the updated current evidence in this challenging field.

New Percutaneous Options for Tricuspid Intervention: How to Identify the Good Clinical Candidate

The tricuspid valve has been neglected for a long time and severe tricuspid regurgitation (TR) was largely undertreated in the past due to a high operative risk. In the last years we observed the development of different less invasive percutaneous options to treat TR. Currently, percutaneous treatments are reserved for high-risk patients presenting with advanced stage disease by which time they are likely to derive a partial benefit at best. There is a limited evidence base, including no randomized trials, to guide the management strategy for severe TR. In the interim we feel that choosing the best device for the most appropriate clinical candidate and with an adequate timing (most probably an “earlier” timing) will be the key combination to improve early and late outcomes of percutaneous treatments.

Percutaneous Inferior Vena Cava Valve Implantation May Improve Tricuspid Valve Regurgitation and Cardiac Output: Lessons Learned

Tricuspid valve regurgitation (TR) can be associated with poor prognosis. Transcatheter valve technology was adopted to treat the upstream effects of severe TR by placing a transcatheter valve in the inferior vena cava (IVC). In this study, we report off-label transcatheter valve implantation into the stented IVC in patients with severe TR for compassionate use. From September 2018 to February 2020, 6 inoperable patients with severe TR who failed medical treatment underwent percutaneous caval valve implantation (CAVI). Severity of TR was confirmed by intraoperative transesophageal echocardiography. Z-stents (Cook, Inc., Bloomington, IN, USA) were placed in the proximal IVC, and then a transcatheter valve was deployed in the suprahepatic cava without rapid pacing. Six patients, 2 females and 4 males, with a mean ± SD age of 74.7 ± 8.0 years were included. The procedure was successfully performed in all 6 patients (100%) employing a 29-mm SAPIEN 3 valve (Edwards Lifesciences, Irvine, CA, USA) with supranominal volume. No procedural complication was detected. At 30 days, TR improved from severe to trace in 1 patient, to mild-moderate in 3 patients, and 2 patients remained with severe TR. Among patients with improved TR, left ventricular ejection fraction increased from 47.5% ± 18.5% to 55% ± 20.4% (P = 0.014). No patient had readmission at 30 days. Four patients needed rehospitalization within 6 months. Percutaneous CAVI is feasible and can be considered as a short-term palliative measure in patients with severe TR. CAVI can improve TR and potentially improve cardiac output in selected patients.

Imaging for Tricuspid Valve Repair and Replacement

Primary or secondary tricuspid regurgitation (TR) represents an important health care burden and challenge which has often been neglected or undertreated in the past. The expansion and reinforcement of the indications for tricuspid valve (TV) intervention in the 2017 editions of the guidelines as well as the introduction of transcatheter tricuspid valve intervention (TTVI) has considerably increased the attention of the community on the TV and the volume of TV interventions in the past years. Depending on the anatomic target, TTVI can be categorized as the following: 1) direct or indirect tricuspid restrictive annuloplasty; 2) direct (edge-to-edge repair) or indirect (coaptation device) restoration of leaflet coaptation; 3) heterotopic tricuspid valve implantation; and 4) transcatheter tricuspid valve replacement. Multimodality imaging has crucial role for the following: 1) patient selection for TTVI and procedure planning; 2) guiding and monitoring the procedure; and 3) assessing and following over time the results of the procedure. The key points for pre-procedural imaging are: 1) accurate quantitation of TR severity; 2) proper identification of the mechanism(s) responsible for the TR; and 3) quantitation of RV dysfunction and pulmonary arterial hypertension. This imaging work-up is essential to select the right type of intervention for the right patient and TV. Transesophageal echocardiography and fluoroscopy imaging is also key for guiding the TTVI procedures and fusion between these 2 modalities may further enhance the quality of procedure guiding.

Impact of inferior caval valve implantation on severity of tricuspid regurgitation and right heart function

AIMS

Severe tricuspid regurgitation (TR) is a common finding in heart failure patients and associated with increased mortality. New interventional therapeutic options are needed as many heart failure patients are unfit for surgery. The TRICAVAL study compared valve implantation into the inferior vena cava (CAVI) with optimal medical therapy (OMT) in patients with severe TR. Here, we report details on the impact of CAVI on TR severity as well as right heart function and morphology.

METHODS AND RESULTS

We randomized 28 patients with severe TR to CAVI (n = 14) with transfemoral implantation of an Edwards Sapien XT valve into the inferior vena cava or OMT (n = 14). Inclusion and exclusion criteria were based on anatomical and clinical parameters. Echocardiographic measurements were performed at baseline, at the first postoperative day and one, three, and twelve months after randomization. As proof of concept of an effective sealing of the inferior vena cava, we detected a significant decrease in systolic hepatic vein reflux volume (11.0 [6.2-21.9] mL vs 3.5 [0.6-8.5] mL, P = .016) and hepatic vein diameter (11.5 [10.0-14.8] mm vs 10.0 [9.3-11.8] mm, P = .034) at thirty-day follow-up. However, CAVI had no significant impact on TR, cardiac function, and morphology.

CONCLUSIONS

Caval valve implantation significantly reduced systolic reflux into the hepatic veins but was not associated with an improvement in cardiac function, morphology, or TR severity.

Treatment of Severe TRIcuspid Regurgitation in Patients with Advanced Heart Failure with CAval Vein Implantation of the Edwards Sapien XT VALve (TRICAVAL): a randomised controlled trial

AIMS

The aim of our study was to compare the impact of implantation of a balloon-expandable transcatheter valve into the inferior vena cava (CAVI) on exercise capacity with optimal medical therapy (OMT) in patients with severe tricuspid regurgitation (TR) and high surgical risk.

METHODS AND RESULTS

Twenty-eight patients were randomised to OMT (n=14) or CAVI (n=14). The primary endpoint was maximal oxygen uptake at the three-month follow-up. Secondary endpoints included six-minute walk test, NYHA class, NT-proBNP levels, right heart function, unscheduled heart failure hospitalisation, and quality of life as assessed by the Minnesota Living with Heart Failure Questionnaire (MLHFQ). Patients underwent follow-up examinations one, three, six, and twelve months after randomisation. Maximal oxygen uptake did not change significantly in either group after three months and there was no difference between the OMT and CAVI groups (-0.1±1.8 ml∙kg-1∙min-1 vs -1.0±1.6 ml∙kg-1∙min-1, p=0.4995). Compared to baseline, CAVI improved NYHA class, dyspnoea, and quality of life after three months. However, there were no statistically significant differences in the secondary endpoints between the groups. Four periprocedural complications occurred after CAVI, resulting in open heart surgery. Four patients in the OMT group and eight patients (including four after conversion to surgery) in the CAVI group died from right heart failure, sepsis or haemorrhage.

CONCLUSIONS

CAVI did not result in a superior functional outcome compared to OMT. Due to an unexpectedly high rate of valve dislocations, the study was stopped for safety reasons.

Quantification of Material Constants for a Phenomenological Constitutive Model of Porcine Tricuspid Valve Leaflets for Simulation Applications

The tricuspid valve is a one-way valve on the pulmonary side of the heart, which prevents backflow of blood during ventricular contractions. Development of computational models of the tricuspid valve is important both in understanding the normal valvular function and in the development/improvement of surgical procedures and medical devices. A key step in the development of such models is quantification of the mechanical properties of the tricuspid valve leaflets. In this study, after examining previously measured five-loading-protocol biaxial stress-strain response of porcine tricuspid valves, a phenomenological constitutive framework was chosen to represent this response. The material constants were quantified for all three leaflets, which were shown to be highly anisotropic with average anisotropy indices of less than 0.5 (an anisotropy index value of 1 indicates a perfectly isotropic response, whereas a smaller value of the anisotropy index indicates an anisotropic response). To obtain mean values of material constants, stress-strain responses of the leaflet samples were averaged and then fitted to the constitutive model (average R2 over 0.9). Since the sample thicknesses were not hugely different, averaging the data using the same tension levels and stress levels produced similar average material constants for each leaflet.

Update on the Current Landscape of Transcatheter Options for Tricuspid Regurgitation Treatment

Most patients with severe tricuspid regurgitation lack treatment options because of prohibitive surgical risk. New transcatheter treatments under development and investigation might be able to address this unmet clinical need. This article gives an update on the landscape of devices for transcatheter tricuspid regurgitation treatment including different approaches (i.e. repair with leaflet approximation or annuloplasty and replacement using orthotopic or heterotopic valves) at different stages of development, from experimental to clinical trial. Repair devices such as the Cardioband or the MitraClip are leading the field with promising preliminary data and further trials are ongoing. However, with implantations of the Gate bioprosthesis, replacement devices are catching up. Potential advantages of different approaches and most recent data are discussed.

Design and evaluation of the crimping of a hooked self-expandable caval valve stent for the treatment of tricuspid regurgitation

To design a hooked self-expandable caval valve stent and determine the best crimping scenario for its percutaneous implantation in the Superior and Inferior Vena Cava (SVC & IVC) for the treatment of tricuspid regurgitation (TR). A hooked, Nitinol based stent design was modeled using SOLIDWORKS and finite element analysis (FEA) was carried out using ABAQUS. The Nitinol material used in this study was modeled in ABAQUS as superelastic-plastic. Two cases were simulated. In case A, the stent model was crimped to 18 F by compressing the stent main body and then: (i) bending both the proximal and distal hooks; (ii) straightening the proximal hooks and bending the distal hooks. In case B, the stent model was crimped to 18 F by: (i) bending the proximal and distal hooks and then compressing the stent main body; (ii) straightening the proximal hooks and bending the distal hooks and then compressing the stent main body. The maximum strain after crimping was used to evaluate the best crimping scenario. Hook straightening produced strains of 10.7% and 10.96% as opposed to 12.6% and 13.0% produced by hook bending. From comparison of results of both cases simulated, it was found that straightening the hooks gave lower strain and thus was the best crimping procedure. The analysis performed in this paper may help understand the critical issue of crimpability of the new stent design. The best crimping scenario can be found based on finite element modeling and simulation. Identifying the best crimping way will also help the design team to optimize the delivery system that will eventually be used to deploy this caval valve stent.

Emerging Transcatheter Options for Tricuspid Regurgitation

Tricuspid regurgitation (TR) presents as either primary valve pathology or secondary to pulmonary or left-sided heart disease. Severe TR portends a worse prognosis independent of age, right ventricular size and function, severe left ventricular dysfunction, and increased pulmonary arterial pressures. Surgical treatment for TR has mostly been limited to patients undergoing mitral valve repair since those at high surgical risk are not candidates for traditional TR surgery. For these patients, minimally invasive techniques could be of great benefit, yet these techniques have been slow to develop because of the various anatomic and physiological aspects of the tricuspid valve apparatus. Several promising new techniques are currently undergoing clinical investigation, including caval valve implantation, percutaneous tricuspid annuloplasty techniques (Trialign, TriCinch, Cardioband), edge-to-edge repair with the MitraClip system, the FORMA device, and the GATE tricuspid Atrioventricular Valved Stent. Further evaluation of their safety and long-term efficacy is warranted prior to commercial approval and widespread adoption.

Catheter-based tricuspid valve replacement: first experimental data of a newly designed bileaflet stent graft prosthesis

OBJECTIVES

Moderate or severe degree tricuspid valve regurgitation (TVR) is associated with high rates of morbidity and mortality. Surgical correction as the only therapeutic option offers unsatisfactory results. Recently, several interventional procedures have been introduced clinically in a limited cohort. We present our initial experiments with an innovative interventional valved stent graft for treatment of TVR.

METHODS

A newly designed porcine pericardium-covered nitinol stent graft with a lateral bicuspid valve was adapted to size in a cadaver study. After haemodynamic testing in an ex vivo perfusion setup, vascular access, valve delivery and function were investigated in an ovine animal model ( n  = 7).

RESULTS

The device was implanted successfully in all animals. Vascular access was established surgically via the femoral vein without any vascular complications. Angiography demonstrated the correct position of the device with proper sealing of both venae cavae in 6 animals. In 1 extremely large animal, the position of the device was considered too cranial but still acceptable. Correct valve function was verified in all animals by both angiography and echocardiography. There were no persistent arrhythmias other than during valve implant. All animals survived the implant procedure and were sacrificed electively.

CONCLUSIONS

This study demonstrated that this new valved stent graft could be delivered safely with correct positioning and valve function in this ovine model. Further long-term studies in animals implanted with the device after creation of tricuspid regurgitation are necessary to prove the haemodynamic benefit of this procedure.

Percutaneous tricuspid valve replacement: orthotopic and heterotopic valves

The tricuspid valve has long been described as the "forgotten valve", leaving tricuspid valve disease relatively neglected. However, the number of people in the United States affected by severe tricuspid regurgitation is growing. Isolated surgery for severe tricuspid regurgitation in the setting of right ventricular heart failure carries a high mortality risk, and therefore, attention to corrective therapies has increased. Because of the different etiologies for tricuspid regurgitation, multiple percutaneous transcatheter options for tricuspid valve repair for severe regurgitation are being studied and have been developed, including annuloplasty systems, leaflet and coaptation devices, vena caval (heterotopic) valve implantations, and tricuspid valve (orthotopic) replacement. In this paper, we review the heterotopic and orthotopic tricuspid valve transcatheter options for severe tricuspid regurgitation.

Recent advances in managing tricuspid regurgitation

Isolated tricuspid valve surgery is usually carried out with very high morbidity and mortality given the complexity of the affected patients. In light of this, trans-catheter tricuspid valve interventions have been emerging as an attractive alternative to surgery over the last few years. Although feasibility has been shown with a number of devices, clinical experience remains preliminary and associated with significant clinical and technical challenges. Here we describe currently available trans-catheter treatment options for severe tricuspid regurgitation implanted in different locations.

Percutaneous tricuspid valve therapies: the new frontier

Moderate-to-severe tricuspid regurgitation (TR) affects ∼1.6 million patients in the USA, of whom only 8000 undergo tricuspid surgery annually; this results in an extremely large number of untreated patients with significant TR. Therefore, there is a large unmet clinical need for patients with severe TR who are not referred for conventional surgery, mainly due to expected high surgical risk. Percutaneous procedures are an attractive alternative to surgery for patients deemed to be high-risk surgical candidates. Whereas over the past few years, the development and clinical use of percutaneous approaches to the aortic valve and mitral valve have been widespread, few data are available about the feasibility and the efficacy of the percutaneous tricuspid valve treatment. This review will explore the available technologies, which are today under evaluation and the preliminary clinical results.

Interventional Imaging of the Tricuspid Valve

Nowadays, reasonable transcatheter tricuspid valve (TV) interventions are emerging as therapeutic options for functional tricuspid regurgitation (TR). The preprocedural planning is based on a multimodality imaging approach, which aims to (1) define the mechanisms of TR, (2) characterize TV morphology, (3) analyze the anatomic relationship between the TV apparatus and other structures, and (4) determine the size of the tricuspid annulus and vena cavae. Intraprocedural guidance is based mainly on transesophageal echocardiography (seldom transthoracic) and fluoroscopy, with the recent introduction of fusion imaging.

Bicaval Medtronic Melody valve implantation for treatment of severe mitral regurgitation following the Mustard repair: A case report

We present a case of successful bicaval Melody valve implantation to treat severe mitral regurgitation in a 44-year-old man with d-transposition of the great arteries, repaired via a Mustard operation. The patient sustained injury to the anterior mitral valve leaflet during laser extraction of a ventricular pacing lead resulting in acute, severe, symptomatic mitral regurgitation. The presence of systemic venous baffles of similar caliber to right ventricular outflow tract conduits allowed for implantation of Melody valves within each baffle. The patient remains asymptomatic with excellent Melody valve function 14 months post procedure.

[Interventional catheter treatment of tricuspid valve regurgitation]

BACKGROUND

The tricuspid valve can be considered the "forgotten" valve because in the past hardly any research has been conducted in this field and as a result only few therapeutic options existed. The prognosis of untreated tricuspid regurgitation (TR) is poor and mortality is high for patients with severe TR. Patients frequently return to medical practices and hospitals because of cardiac decompensation, with shortness of breath and leg edema.

OBJECTIVE

Recent years have seen more development in catheter-based treatment options. Currently, several devices are in clinical evaluation, which are presented in this article.

MATERIAL AND METHODS

A web-based literature search was carried out and information was gathered at international cardiology meetings (TCT 2016 in Washington, DGK 2017 in Mannheim, EuroPCR 2017 in Paris).

RESULTS AND CONCLUSION

There are various options for interventional catheter procedures for TR, which are being investigated within the scope of clinical studies. Most aim at reducing the tricuspid annular diameter and optimizing leaflet coaptation. Because of these new therapy options patients can now be treated who were considered untreatable in the past because of the high perioperative mortality.

Current Treatment Strategies for Tricuspid Regurgitation

PURPOSE OF REVIEW

Tricuspid regurgitation is common; however, recognition and diagnosis, clinical outcomes, and management strategies are poorly defined. Here, we will describe the etiology and natural history of tricuspid regurgitation (TR), evaluate existing surgical outcomes data, and review the evolving field of percutaneous interventions to treat TR.

RECENT FINDINGS

Previously, the only definitive corrective therapy for TR was surgical valve repair or replacement which is associated with significant operative mortality. Advances in percutaneous valve repair techniques are now being translated to the tricuspid valve. These novel interventions may offer a lower-risk alternative treatment in patients at increased surgical risk. Significant TR adversely impacts survival. Surgery remains the only proven therapy for treatment of TR and may be underutilized due to mixed outcomes data. Early experience with percutaneous interventions is promising, but large clinical experience is lacking. Further study will be required before these therapies are introduced into broader clinical practice.

Design and Development of Novel Transcatheter Bicaval Valves in the Interventional Treatment of Tricuspid Regurgitation

The concept of heterotopic implantation of transcatheter tricuspid valve is new and has shown promising results thus far. While the Reynolds shear stress values measured in the vicinity of this valve are relatively low, the values at some time points are higher than the threshold of platelet activation. Hence, in this study, we aim to reduce these values with an innovative stent design. It was shown that the Reynolds shear stress values measured were lower than those of valves made of generic stent design and the maximum Reynolds shear stress values in the vicinity of the valves was very low (∼10 dynes/cm² ). The results also depicted the interesting flow phenomenon of this non-physiological treatment approach. Thus, this study has shown that bicaval valves could potentially be considered as a minimally invasive option to treat tricuspid regurgitation and valve design improvements could reduce the flow disturbances that were observed.

Percutaneous Treatment of the Tricuspid Valve Disease: New Hope for the "Forgotten" Valve

Tricuspid valve disease is a frequent condition but is currently undertreated. A limited number of patients undergo an isolated surgical tricuspid repair, and this intervention is associated with poor outcomes, especially in patients with previous cardiac surgery. Most patients are only medically treated, despite the impact of severe tricuspid regurgitation on functional status and long-term survival. Transcatheter therapies represent a promising alternative for patients with severe tricuspid regurgitation and high surgical risk. In the last few years, several percutaneous alternatives have been developed for the treatment of functional tricuspid regurgitation. Imaging techniques play an indispensable role in patient selection, procedural guidance and follow-up. The current available transcatheter options for native tricuspid valve disease can be divided into 3 main groups: heterotopic caval valve implantation, annuloplasty devices, and coaptation devices. In patients with previous tricuspid valve surgery, transcatheter valve-in-valve and valve-in-ring procedures have been reported. This review provides a detailed analysis of the novel transcatheter alternatives for the treatment of tricuspid valve disease that have already been successfully implanted in humans, as well as the most important aspects of tricuspid valve anatomy and imaging assessment.

Advances in percutaneous interventional therapies: the tricuspid valve

Tricuspid regurgitation (TR) is a prevalent valve condition, with an estimated 1.6 million people in the USA living with moderate or greater severity. Functional TR, which predominantly develops due to left-sided heart disease, is the predominant condition affecting the tricuspid valve in the Western world and severe TR is associated with substantial morbidity and mortality. In part, due to a prolonged latency period with insidious symptoms, patients are often referred for surgery at advanced stages, with associated increased or prohibitive surgical risk. In addition, surgical treatment can result in high rates of recurrence. Therefore, there is an unmet need for percutaneous therapies that may provide a relatively low-risk treatment option. There are several devices with early human feasibility data available that will be reviewed in this article.

Quantification and comparison of the mechanical properties of four human cardiac valves

OBJECTIVE

Although having the same ability to permit unidirectional flow within the heart, the four main valves-the mitral valve (MV), aortic (AV), tricuspid (TV) and pulmonary (PV) valves-experience different loading conditions; thus, they exhibit different structural integrity from one another. Most research on heart valve mechanics have been conducted mainly on MV and AV or an individual valve, but none quantify and compare the mechanical and structural properties among the four valves from the same aged patient population whose death was unrelated to cardiovascular disease.

METHODS

A total of 114 valve leaflet samples were excised from 12 human cadavers whose death was unrelated to cardiovascular disease (70.1±3.7years old). Tissue mechanical and structural properties were characterized by planar biaxial mechanical testing and histological methods. The experimental data were then fitted with a Fung-type constitutive model.

RESULTS

The four valves differed substantially in thickness, degree of anisotropy, and stiffness. The leaflets of the left heart (the AV leaflets and the anterior mitral leaflets, AML) were significantly stiffer and less compliant than their counterparts in the right heart. TV leaflets were the most extensible and isotropic, while AML and AV leaflets were the least extensible and the most anisotropic. Age plays a significant role in the reduction of leaflet stiffness and extensibility with nearly straightened collagen fibers observed in the leaflet samples from elderly groups (65years and older).

CONCLUSIONS

Results from 114 human leaflet samples not only provided a baseline quantification of the mechanical properties of aged human cardiac valves, but also offered a better understanding of the age-dependent differences among the four valves. It is hoped that the experimental data collected and the associated constitutive models in this study can facilitate future studies of valve diseases, treatments and the development of interventional devices.

STATEMENT OF SIGNIFICANCE

Most research on heart valve mechanics have been conducted mainly on mitral and aortic valves or an individual valve, but none quantify and compare the mechanical and structural properties among the four valves from the same relatively healthy elderly patient population. In this study, the mechanical and microstructural properties of 114 leaflets of aortic, mitral, pulmonary and tricuspid valves from 12 human cadaver hearts were mechanically tested, analyzed and compared. Our results not only provided a baseline quantification of the mechanical properties of aged human valves, but a age range between patients (51-87years) also offers a better understanding of the age-dependent differences among the four valves. It is hoped that the obtained experimental data and associated constitutive parameters can facilitate studies of valve diseases, treatments and the development of interventional devices.

Management of Tricuspid Regurgitation: The Role of Transcatheter Therapies

Surgical treatment is the gold standard treatment of functional tricuspid regurgitation (FTR) but this carries high risks of morbidity and mortality. Percutaneous procedures are an attractive alternative to surgery for selected patients deemed to be high-risk surgical candidates. A number of tricuspid transcatheter devices have been developed to treat FTR, but at present, evidence of their efficacy and safety is scarce. Preliminary data have shown promising results, but ongoing and future studies will provide a clearer picture of the benefits of these new techniques.

Transcatheter Treatment of Functional Tricuspid Regurgitation Using the Trialign Device

Functional tricuspid regurgitation (TR) represents an important unmet need in clinical cardiology given its prevalence, adverse prognostic impact and symptom burden associated with progressive right heart failure. Several transcatheter techniques are currently in early clinical testing to provide alternative treatment options for patients deemed unsuitable for tricuspid valve surgery. Amongst them, the TrialignTM device (Mitralign, Inc.) represents a novel percutaneous tricuspid valve annuloplasty technique, which aims to reduce tricuspid annular dilatation in functional TR by delivering and cinching two pledgeted sutures to the posterior portion of the tricuspid annulus via transjugular access. Early clinical data suggest the Trialign technique is safe and feasible, and associated with an improvement in quality-of-life measures. However, further studies are needed to confirm these data in larger cohorts of patients with longer follow up. In addition, future trials need to address the question whether TR reduction with the Trialign and other devices leads to an improvement in the patient`s functional status and prognosis, over and above medical treatment alone.

State-of-the-Art Review of Echocardiographic Imaging in the Evaluation and Treatment of Functional Tricuspid Regurgitation

Functional or secondary tricuspid regurgitation (TR) is the most common cause of severe TR in the Western world. The presence of functional TR, either isolated or in combination with left heart disease, is associated with unfavorable natural history. Surgical mortality for isolated tricuspid valve interventions remains higher than for any other single valve surgery, and surgical options for repair do not have consistent long-term durability. In addition, as more patients undergo transcatheter left valve interventions, developing transcatheter solutions for functional TR has gained greater momentum. Numerous transcatheter devices are currently in early clinical trials. All patients require an assessment of valve morphology and function, and transcatheter devices typically require intraprocedural guidance by echocardiography. The following review will describe tricuspid anatomy, define echocardiographic views for evaluating tricuspid valve morphology and function, and discuss imaging requirements for the current transcatheter devices under development for the treatment of functional TR.

Diagnosis and treatment of tricuspid valve disease: current and future perspectives

The assessment and management of tricuspid valve disease have evolved substantially during the past several years. Whereas tricuspid stenosis is uncommon, tricuspid regurgitation is frequently encountered and is most often secondary in nature and caused by annular dilatation and leaflet tethering from adverse right ventricular remodelling in response to any of several disease processes. Non-invasive assessment of tricuspid regurgitation must define its cause and severity; advanced three-dimensional echocardiography, MRI, and CT are gaining in clinical application. The indications for tricuspid valve surgery to treat tricuspid regurgitation are related to the cause of the disorder, the context in which it is encountered, its severity, and its effects on right ventricular function. Most operations for tricuspid regurgitation are done at the time of left-sided heart valve surgery. The threshold for restrictive ring annuloplasty repair of secondary tricuspid regurgitation at the time of left-sided valve surgery has decreased over time with recognition of the risk of progressive tricuspid regurgitation and right heart failure in patients with moderate or lesser degrees of tricuspid regurgitation and tricuspid annular dilatation, as well as with appreciation of the high risks of reoperative surgery for severe tricuspid regurgitation late after left-sided valve surgery. However, many patients with unoperated severe tricuspid regurgitation are also deemed at very high or prohibitive surgical risk. Novel transcatheter therapies have begun to emerge for the treatment of tricuspid regurgitation in such patients. Experience with such therapies is preliminary and further studies are needed to determine their role in the management of this disorder.

Transcathether Valve Replacement and Valve Repair

Transcatheter aortic valve replacement for treatment of aortic stenosis has now become an accepted alternative to surgical valve replacement for some patients. In addition, transcatheter mitral valve repair is also routinely used in high surgical risk patients with mitral regurgitation. Other transcatheter procedures are in rapid development. The current review attempts to summarize the procedures and echocardiographic imaging used for transcatheter valve replacement or valve repair.