Percutaneous Tricuspid Valve Repair

Anatomy and Physiology

The tricuspid valve (TV) is the largest of all four cardiac valves and is located closer to the apex than the mitral valve. The TV separates the right atrium and ventricle with its fibrous annulus, three leaflets, two papillary muscles, and chordae tendinea. Due to their anatomy and position, the TV leaflets are referred to as the anterior, posterior, and septal. The anterior leaflet is the largest of the three, with the septal leaflet being the smallest. The septal leaflet is fixed medially from the tricuspid annulus on top of the interventricular septum. With the fixation of the septal leaflet, tricuspid annulus sizing is based on the size of the base of the septal leaflet. The anterior papillary muscle provides chordae attachment to the anterior and posterior leaflets while the medial papillary muscle provides chordae attachment to the posterior and septal leaflets.

The tricuspid annulus has a very complex structure that differs greatly from the symmetric mitral annulus. The tricuspid annulus may change shape with different load conditions. This must be taken into consideration when designing or placing tricuspid valve rings. Another area of interest when operating near the TV is Koch’s triangle. This area has borders that involve the hinge of the septal leaflet of the TV, the orifice of the superior margin of the coronary sinus, and the tendon of Todaro. This area is of great surgical importance as the atrioventricular node lies within this triangle. The triangle of Koch must be avoided along with the blood supply to the conduction system to avoid any atrial arrhythmias. The risk of damage to the conduction system is greater with the replacement of the TV than with a repair.[2]

Tricuspid Regurgitation (TR)

TV regurgitation occurs when there is a backward flow of blood from the right ventricle to the right atrium and can result from a multitude of issues classified as either primary or secondary. Primary causes occur 25% of the time, while secondary causes occur the remaining 75% of the time.   

Primary

• Rheumatic heart disease
• Myxomatous
• Endocarditis
• Carcinoid disease
• Ebstein anomaly 
• Endomyocardial fibrosis
• Traumatic causes (ex- blunt chest injury, cardiac laceration)
• Iatrogenic (RV biopsy, pacemaker/defibrillator leads)

Secondary (Functional)

• Left heart disease due to left ventricle dysfunction or valve dysfunction causing pulmonary hypertension 
• Pulmonary hypertension (due to chronic lung disease, pulmonary embolism) 
• Right ventricular dysfunction (right ventricle infarction, myocardial disease, chronic right ventricular ischemia)

Tricuspid Stenosis (TS)

TV stenosis occurs when the valve is narrow, and therefore, not enough blood can flow from the right atrium into the right ventricle. TS most commonly occurs due to rheumatic heart disease. Isolated TS is rare as there will usually be some form of TR. The pathophysiology of the stenosis is similar to mitral valve stenosis in which the chordae have shortening with fusion and leaflet thickening. Calcific deposits of the valve occur late in the disease process.

Patients usually have signs of venous congestion with distension of the jugular veins, ascites, peripheral edema, and pleural effusions due to the significant increase in the right atrial pressures. Over time, the right atrium becomes dilated and thickens to accommodate the elevated pressures. The right atrium has higher diastolic pressures when compared to the right ventricle by 3 to 5 mm Hg. Patients may present with an array of symptoms ranging from fatigue with malaise to reduced cardiac output if the stenosis is significant. Physical exam findings may have palpable liver due to venous congestion with a fluid wave due to ascites. The TS murmur consists of a diastolic murmur at the lower left sternal border at the fourth intercostal space. The tricuspid valve stenosis murmur is softer, higher-pitched, and shorter than that found with mitral stenosis. The murmur intensity increases with any maneuver than increases blood flow across the TV.

Indications

If a patient is having a surgical intervention for the treatment of mitral valve disease, it is critically important to measure the TV annulus with echocardiography to assess their need for TV surgical intervention in the case of concomitant TV regurgitation.[3] In the majority of patients, the leading cause of tricuspid valve disease is due to left-sided heart disease. Recent studies have shown TV disease to have an impact on the survival of heart failure patients. These patients should be evaluated for repair. When TV disease is managed non-operatively for long periods of time, surgical intervention can become prohibited due to the major changes the valve disorder causes to the anatomy and physiology of the body. When evaluating patients for TV intervention, many of the patients have a high-risk profile with multiple medical comorbidities. Having less invasive techniques for repair would help to increase success rates for high-risk non-open surgery candidates, therefore decreasing morbidity and mortality. 

Indications for Repair

• Severe tricuspid stenosis with associated symptoms (gradient > 5cm or surface area <1 cm)
• Severe primary or secondary tricuspid regurgitation with symptoms
• When the patient is undergoing left-sided valve surgery with moderate to severe primary tricuspid regurgitation or tricuspid stenosis (symptomatic or asymptomatic) or mild to moderate progressive functional (secondary) tricuspid regurgitation with a dilated annulus (>40 mm or >21 mm/m2)
• The endocarditis of the tricuspid valve
• Progressive right ventricular dilatation and/or dysfunction in the setting of asymptomatic or mildly symptomatic primary tricuspid regurgitation
• Carcinoid involvement of the tricuspid valve 
• Congenital malformations of the tricuspid valve 
• Traumatic or iatrogenic injuries to the valve due to pacemaker wires or due to taking biopsies of the heart or lungs
• Undergoing other cardiac procedures with tricuspid disease

Contraindications

Here are some contraindications to the procedure:

• Surgically fit patients who would benefit more from an open repair
• Unable to tolerate systemic anticoagulation
• Bleeding disorder with coagulopathy 
• Thrombus in the femoral, jugular, right atrium, or the superior/inferior vena cavae

Equipment

The following equipment is required:

• Cath lab with fluoroscopy machine
• Transthoracic echocardiography and transesophageal echocardiography machine
• Tricuspid valve repair or replacement device 
• Multiple wires and catheter sizes
• Code cart 
• Sterile gown and gloves, sterile drape
• Operative cardiac surgery team and open surgical trays
• Anesthesia

Personnel

Successful percutaneous repair of the tricuspid valve requires a skilled team consisting of the following:

• Interventional cardiologist
• Cardiac nurses
• Cath lab personnel
• Cardiothoracic surgeons
• Skilled ultrasonographer
• Anesthesia team

Preparation

Prior to undergoing endovascular catheter-based repair or replacement of the tricuspid valve, the patient should undergo echocardiography to examine the TV. The recommended view of the TV is through 2D transthoracic echocardiography with color doppler to examine the severity of the TV pathology or any associated right ventricular dysfunction. Two-dimensional echocardiography can identify 80% to 90% of patients even with trivial TV disorders.[4] 

If the valve cannot be seen adequately with 2D echo, real-time 3D echocardiogram or cardiac magnetic resonance can be done to fully assess right ventricular dysfunction, annular dilation, and leaflet tethering without limitation.[5] Because the posterior leaflet has multiple scallops and visualization is limited with a cross-sectional view on a 2DE, some patients have been diagnosed with having only two or greater than three tricuspid leaflets.[3] 

A cardiac structural specialist may need to review the imaging regardless of whether it be a 2D or 3D echo. In addition to proper imaging, it is imperative that this procedure is performed under sterile conditions and that everyone involved at the cath lab table is properly scrubbed and wearing sterile gowns, gloves, eyewear, and scrub caps. The lead should be worn by everyone in the room. The area of access should be sterilely prepped and draped prior to starting the procedure.

Technique or Treatment

The tricuspid valve has long been forgotten, and there is still some hesitation in treating sole tricuspid lesions. Severe tricuspid lesions are associated with a poor prognosis and should be repaired or replaced. Tricuspid valve repair or replacement procedures are usually performed in conjunction with the left-sided cardiac procedures during the same operative time. The current gold standard for surgical repair is ring annuloplasty with an incomplete semi-rigid annuloplasty ring for repair of tricuspid regurgitation. Transcatheter interventions for TR are becoming more popular due to the success of aortic and mitral valve repair/replacements via transcatheter intervention. Tricuspid stenosis is most commonly repaired with endovascular valvotomy or valvuloplasty.[6]

Since a very small fraction of patients are considered surgical candidates, there has been a renewed interest in developing percutaneous transcatheter devices for tricuspid valve disorders. Percutaneous techniques are likely to increase in the future due to improved technology and increased awareness of the long-term effects of tricuspid regurgitation and stenosis. There are multiple endovascular techniques available for total replacement of the tricuspid valve or endovascular repair of TR or TS. The most important preoperative assessment prior to the intervention is appropriate patient selection. Post-procedure, the patients must all have repeat echocardiography, including measurement of the valve gradient. The ideal candidate to receive percutaneous catheter treatment has been receiving optimal medical treatment, has high surgical risk, and severe TR/TS.

Transcatheter Replacement of Tricuspid Valve

• Transcatheter tricuspid valve replacement is still in the early stages of development and requires much more clinical research and patient studies. 
• There are several prosthetic tricuspid valves
• Bioprosthetic xenopericardial valve
• The bioprosthetic valve is a xenopericardial leaflet bioprosthesis valve that has a self-expanding nitinol scaffold that can be inserted via a jugular approach or via a mini-thoracotomy. The placement of this valve allows full orthotopic transcatheter tricuspid valve replacements. The valve is available in multiple sizes, and it is recommended to oversize the prosthetic with respect to the annulus size. CT imaging is very important to measure the distance between the tricuspid valve annulus to the right coronary artery. This is a very important measurement as it helps to avoid damage to the right coronary artery. 
• As very few have been placed, this type of valve replacement is still under review. 
• Nitinol Self Expanding Valve
• This nitinol self-expanding valve is another percutaneous transcatheter valve option. The valve is made of an elastic nitinol frame with an inner valve apparatus. The frame gets anchored into the TV annulus by multiple arms, which secures the new valve into the native TV leaflets. Anchoring the valve axially allows avoidance of the conducting system. The new valve functions with two leaflets. The two leaflets move to the center of the lumen during diastole, allowing the filling of the right ventricle. When the heart is in systole, the leaflets close and allow full coaptation of the TV annulus.

Challenges

• There are multiple challenges that stand in the way of transcatheter placement of the tricuspid valve. The femoral veins or internal jugular veins serve as the main access sites for placement of the venous sheath. The internal jugular vein serves as the best access site as it provides less curve for the sheath and valve to pass through. 
• The tricuspid valve is not calcified like the aortic valve, so therefore the valve does not “seat” like a TAVR valve. Larger valves may be needed to help properly anchor the valve into place. 
• The long durability of the TV is unknown. Patients will need to be followed closely to monitor the wear on the valve. 
• Replacing the TV can lead to an abrupt change in the right ventricular afterload. 
• The conduction system of the heart lies so close to the triangle of Koch, which is near the commissure between the septal and anterior leaflets of the tricuspid valve. Placement of the valve into this area can cause a complete AV block. 
• Lifelong anticoagulation will be required due to the low flow on the right side of the heart and size of the TV prosthesis.
• Placement of a new TV may lead to residual regurgitation due to the anatomical sizing and shape of the valve. 

Transcatheter Treatment of Tricuspid Regurgitation

• Functional TR is the most common reason for intervention for patients presenting with tricuspid pathology. 
• There are multiple new techniques that are going through early trials for TR intervention. Many of the techniques remain preliminary but are making excellent progression. 
• There are several percutaneous techniques available for repair or replacement of the TV.
• Percutaneous treatment for TR:
• Coaptation Device- Tricuspid valve clipping system, Mitral valve clipping system, edge to edge valve repair system
• Annuloplasty Device- Tricuspif aligning system, Direct tricuspid valve annuloplasty device, Tricuspid valve anchoring system
• Vena Cava Valves

Mitral Valve Clipping System

• After such success for the repair of the mitral valve, the Mitral valve clipping system was used on the tricuspid valve. This system is now called the “triclip” and is available for use. 
• The technique requires a percutaneous transjugular or transfemoral approach for access to the valve. 
• The TRILUMINATE trial has shown excellent results for the placement of the Tricuspid clipping system. 
• Viewing of the catheter and clip placement is done via 2D echo and 3D echo. Recent publications suggest transgastric views have excellent visualization of the anatomy.[7]
• The technique is performed through the femoral vein with a 7 Fr catheter. The wire is advanced to gain access to the superior vena cava and right atrium. The mitral clipping system is inserted over the wire to the right atrium, and the wire is removed. The mitral clipping catheter is inserted misaligned by 90 degrees or 180 degrees. The catheter is then aspirated to avoid any form of an air embolism.  The misalignment allows for the straddling of the mitral clipping catheter on the guidewire. Once the straddling is completed, the device is activated to deflect the clip toward the TV. The goal of placing the clip is to be as perpendicular as possible to the leaflet without injuring the interatrial wall. Fluoroscopy and echo imaging is very important at this point in the procedure. When the correct imaging is obtained, the clip can be opened over the desired commissure. The device clip is then closed over the leaflet and pushed toward the right ventricle. Imaging will show the capture of the clip on the leaflets. Once the leaflets are captured, the placement of the clip should be performed through imaging. Once the clip has been released, the valve should be assessed for placement, the amount of regurgitation remaining, and possible new tricuspid stenosis. 

Edge to Edge Clipping System

• This device is used for edge to edge repair of the TV for TR by using transfemoral access. This device is placed and guided into a position like the mitral clipping system. The device captures the TV leaflets by using metal clasps to grasp the leaflets and paddles to grasp the leaflets against the spacer. The spacer decreases leaflet stress while gaining the coaptation of the leaflets. Transesophageal echo and fluoroscopy are used for monitoring during the procedure. The device is steered in place, similar to the mitral clipping system. 

Tricuspid valve align the system

• The Tricuspid aligning system was developed from the Mitral align system that is used for mitral valve repair. This system uses a transjugular approach and is a suture-based annuloplasty system used to reduce the tricuspid annular diameter by plicating the leaflet tissue. The procedure uses a pair of polyester sutures that are placed into the tricuspid annulus next to the anteroposterior and posterior-septal commissures using an over-the-wire technique. Once the wire is through the annulus, the pledget delivery system is used. The suture is then cinched using a polyester suture that closes the tricuspid posterior leaflet and fixates it to the atrial side. A suture can be placed into the anterior annulus to help add a closure of the space. 
• This system produces bicuspidization of the TV. 
• The SCOUT trial has shown safe results with a 37% mean reduction in the tricuspid annulus and a 59% reduction in the regurgitant orifice area.

Direct Tricuspid Valve Annuloplasty system

• This system uses a percutaneous approach with direct annuloplasty repair of the TV. The device is placed into the tricuspid annulus by a series of anchors that are passed through the TV annulus into the right ventricle myocardium. You must be sure to avoid the septal area to avoid injury to the AV node. After the anchors are placed, and the wires are set, the system is cinched under transesophageal echo guidance. This allows for closure of the annular septal lateral diameter. 
• Over the course of 6 months, the TRI-REPAIR trial has shown a 9% reduction of the annular septal-lateral diameter and a 50% reduction of the proximal isovelocity surface area. 

Tricuspid valve anchoring system

• This is another type of annuloplasty device. This device is designed for percutaneous use to help TV remodeling. A transfemoral approach is used for this system. A deflectable catheter with a stainless steel corkscrew and a coil system in the tip anchors to the tricuspid annulus. The corkscrew is then connected to a Dacron band. The annulus, after being anchored with the screw, is then connected to the band, which creates traction throughout the band and annulus. Fluoroscopy and TEE are used for proper placement of the fixation device into the anterior tricuspid annulus. Once in place, it is cinched further to improve coaptation. After the catheter is tightened, a self-expandable nitinol stent is placed into the inferior vena cava to help keep tension on the system. 
• The PREVENT study is currently enrolling patients for studies. 

Valve Spacing System

• This device is used as a valved spacer. The spacer is delivered through a subclavian venous approach and then anchored to the right ventricle apex. The valve spacer is placed into the area of TV regurgitation. Placing the spacer allows the area to act as a platform, which in turn helps to increase valve coaptation. An incision is made on the chest wall, and the device is placed into this pocket, the area of proximal fixation. 

Tricuspid Valve annular ring system

• This system uses percutaneous access that places a TV annular ring to help remodel the native TV. The entire system is repositionable and retrievable before it is deployed. 

Vena Cava Valves

• The vena cava valve is another transfemoral percutaneous approach to treat TR. This technique involves the placement of a valve into the inferior vena cava alone or into both the inferior and superior vena cavae. The placement of the valves is done to reduce the backward flow from the heart into the hepatic, abdominal, and other peripheral areas. The overall goal is to improve systemic venous congestion. The long term outcomes and complications are not known as this does not fix the problem of TR. This device may also increase thrombotic episodes, but the use of anticoagulation is not known, as further studies need to be performed. 

Bicaval Valve System

• This is another valve concept very similar to the previously mentioned valve systems. The valve is placed percutaneously with placement into the bicaval position. The valve consists of a bicuspid valve covered stent with each end being in the superior vena cava and inferior vena cava. There is also a lateral bicuspid element made of porcine pericardium that has a low closing pressure. The bicaval valve aims to reduce retrograde flow. The device can be fully repositioned and retrieved before fully releasing the valve.[8] The native tricuspid valve is not touched during this procedure. Other percutaneous procedures are able to be performed through this device as well. 

Transcatheter Treatment of Tricuspid Stenosis

• Percutaneous transcatheter repair of the TV with stenosis can be performed using double-balloon valvotomy or valvuloplasty. 
• Intervention can be performed on native TV stenosis or on the stenosis of a bioprosthetic valve. 
• There are multiple options for the intervention for TS. Double balloon valvotomy is a common treatment for TS, and single balloon valvuloplasty is another option. 
• Severe TS treatment should have valve replacement as a first-line option. If the patient is too high risk for open surgical repair, then the percutaneous repair should be performed. 

Double Balloon Valvotomy

• When performing a double-balloon valvotomy, access should be gained in each groin percutaneously. The area of insertion should be injected with an anesthetic. After proper anesthesia, the femoral veins should be accessed via ultrasound-guided placement of the needle and sheath. The wires are then passed into the right atrium. The angiocatheter is passed over the wire into the right ventricle. The valve gradient should be checked across the TV, and a right ventricular angiogram can be performed for pre and post balloon dilation findings. The curved end of the wires should be passed through the TV and placed into the proximal right ventricle. A 9 Fr balloon is then passed over the wires and placed through the TV under fluoroscopic guidance. Once the balloons are in the correct position, a right atrial angiogram under fluoroscopy with a slight inflation of the balloons can be performed for definitive placement.[9] The balloons can then be insufflated at the same time until adequate dilation of the valve occurs. When dilating the TV, careful insufflation of the balloons should be done to avoid causing a large jet of tricuspid regurgitation. If the valve gradient does not change, the balloon diameter can be increased in size, and then dilation can be re-attempted. Once adequate reduction in the TV gradient and an increase in the total surface area of the TV are achieved, the wires and balloons can be removed. A post-procedure echo should be performed. 

Balloon Valvuloplasty

• Preoperative imaging is obtained with a measurement of the gradient across the tricuspid valve. The valve annulus diameter should be measured along with the size of the right atrium. Balloon valvuloplasty is performed by gaining right groin access via ultrasound guidance with anesthesia injected into the site. Proceed to perform a right heart cath. A 7 Fr sheath is used with the advancement of the wire into the right atrium. The balloon should be passed over the wire and stopped at the tricuspid valve to measure the diameter of the balloon on the TV annulus. The balloon size should be 80% to 110% of the valve annulus size. Once adequate measuring takes place, the wire is then advanced into the right or left pulmonary artery in order to achieve proper position. The balloon is then passed over the wire through the TV. The balloon is inflated and drawn back until the balloon is in the orifice of the TV. The balloon is held in place with small progressive dilations performed. This is done until the pressure gradient drops across the TV. Careful attention must be performed to avoid creating regurgitation across the valve. Once the desired mean drop in the gradient is achieved, the balloon and wire can be withdrawn with completion of the procedure. Post-procedure echocardiography should be performed.

Complications

The complications associated with tricuspid valve repair are very similar, whether intervention is performed via open repair or transcatheter repair. Mortality of tricuspid valve replacement is 3 to 4 times higher when compared to another single valve open or percutaneous procedures. Surgical intervention for tricuspid disorders can be associated with a high risk of morbidity and mortality, with perioperative mortality reaching up to 10% in selected cases.[10]

• Catheter-related complications to access site -hematoma, arteriotomy, dissection, arteriovenous fistula
• Myocardial infarction due to damage or irritation to the right coronary artery
• Arrhythmias and heart blocks
• Prosthetic valve malfunction
• Heart failure
• Perioperative bleeding and resulting blood products transfusion-related complications
• Drug reactions
• Surgical site infections and/or the valve prosthesis
• Sepsis
• Pulmonary complications - pneumothorax, pneumonia, embolisms
• Renal failure - due to concomitant use of contrast dye
• Stroke

Clinical Significance

Catheter-based treatment of the tricuspid valve is a recently new approach to treating tricuspid pathology. Endovascular repair of the valve avoids sternotomy and cardiopulmonary bypass. Tricuspid valve disorders have long been neglected based on beliefs that their rarity in prevalence does not readily determine patient prognosis. Untreated tricuspid valve disorders along with other cardiac diseases cause the patient higher morbidity and mortality.[11] Any significant tricuspid valve disorder should be addressed.

Enhancing Healthcare Team Outcomes

Tricuspid valve disorders are rare findings; and, if discovered, should be treated as long as the patient is symptomatic or has severe findings. As we become more advanced with replacement or repair of tricuspid valve disorders using endovascular techniques, we should have more involvement and interprofessional care from multidisciplinary teams. An interprofessional team should include an anesthesia team, cardiologists, cardio-thoracic surgeons, and cardiac intensivists. Preoperative echocardiographic evaluation of the tricuspid valve requires coordination between the ultrasound sonographer and the cardiology team. The intraoperative repair of the valve requires closed-loop communication between the cardiac surgeon, anesthesiologist, cardiologist, circulating nurse, and cath lab techs.

Close communication is vital for successful endovascular tricuspid valve repair. Postoperative care requires skilled intensivists and intensive care nurses. The untreated severe or symptomatic disease leads to poor outcomes with the patient’s overall health. Percutaneous techniques for tricuspid repair/replacement are likely to increase in the future due to improvement in technology and new studies showing improved long term outcomes in the treatment of tricuspid valve disease.

Nursing, Allied Health, and Interprofessional Team Interventions

Interventions regarding endovascular repair of the tricuspid valve come from many of the teams involved. The medical and surgical team must work as one to provide excellent care to the patient. Interventions for this procedure are provided from multiple teams of specialists which overall provides better outcomes for the patient.

Nursing, Allied Health, and Interprofessional Team Monitoring

The monitoring of the patient requires excellent interprofessional communication between nurses, techs, and physicians of multiple specialties. The pre-operative, intra-operative, and post-operative management of the patient requires a skilled team.