The success of transcatheter aortic valve replacement (TAVR) has inspired physicians to apply less invasive percutaneous techniques to other valvular conditions. At times, it requires thinking outside the box. Or, in the case of the tricuspid valve, outside the heart.

Right-sided valve disorders such as tricuspid regurgitation historically take a back seat to aortic and mitral valve diseases. They claim a minuscule proportion of valvular disease-related deaths—0.2 percent—and often are asymptomatic (Am Heart J 2014;167:562-567). Yet an estimated 1.6 million people in the U.S. have severe or moderate tricuspid valve regurgitation, which can lead to edema, fatigue and liver dysfunction. Due to their comorbidities, few patients with severe tricuspid regurgitation are good candidates for surgery.

“Hence, many of these patients are treated just medically,” says Brian P. O’Neill, an interventional cardiologist at Temple Heart & Vascular Center in Philadelphia.

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“It is often viewed as not life-threatening enough to require an open heart operation, so there are very few isolated tricuspid valve replacement procedures that are done,” adds William W. O’Neill, MD, medical director at Henry Ford Hospital’s Center for Structural Heart Disease in Detroit and Brian O’Neill’s father. Annually, surgeons perform only about 8,000 to 9,000 procedures in the U.S. “There is a strong need to develop something less invasive.”

This summer, the two O’Neills and Adam Greenbaum, MD, director of the catheterization laboratory at Henry Ford, performed a novel procedure to treat a patient with severe tricuspid regurgitation: They implanted an Edwards Lifesciences Sapien XT TAVR valve in the patient’s inferior vena cava (IVC) at the junction of the right atrium to replace her failing tricuspid valve.

Brian O’Neill served as proctor. Proctor and procedural champion, actually.

On the shoulders of others

The Henry Ford-Temple team was not the first to think of an off-label use of a transcatheter valve for tricuspid regurgitation. Three years ago, researchers reported that they successfully implanted Medtronic’s Melody transcatheter pulmonary valve in tricuspid tissue valves in 15 patients (J Am Coll Cardiol 2011;58:117-122). In 2013, cardiologists at Charité Universitätsmediz in Berlin described successfully implanting the Sapien valve in three patients with severe tricuspid regurgitation: one single-valve approach in the IVC and two dual-valve approaches in the superior vena cava and IVC (J Am Coll Cardiol 2013;61:1929-1934).

Inspired by the German physicians’ first-in-man experience, Brian O’Neill scoured clinical and animal studies to develop a protocol for the FDA for an Investigational Device Exemption trial. The investigator-initiated study already had been submitted to the FDA when Henry Ford’s structural heart group agreed they had a good tricuspid regurgitation candidate for compassionate treatment using a percutaneous approach.

The transfemoral procedure required them to insert a catheter and then a stent in the IVC to anchor the valve that followed. The procedure took two hours and the patient remained hospitalized for five days. As their first patient to undergo this approach, clinicians wanted to keep an eye on her, William O’Neill explains, but future patients should be discharged much sooner. “Once the procedure becomes more established, it is mainly looking at the femoral vein closure site,” he says. “I could foresee a one- or two-day stay in the hospital.”

Brian O’Neill’s protocol was approved and he is working on getting Temple’s Institutional Review Board to give a green light. The trial will enroll 30 high-risk patients with severe tricuspid regurgitation for percutaneous treatment using the Sapien XT, with 30-day, six-month, 12-month and five-year follow-up.

“We don’t really know long-term how these patients do,” Brian O’Neill says. “We’re still trying to define the right type of patient in whom this procedure really will be effective. We are hoping with this initial pilot study to have a better sense and serve as a springboard for a larger pivotal trial in the future.”

Making a case for the IVC

The tricuspid valve’s crescent shape and triple leaflet construction may make it a difficult design for manufacturers of prosthetic devices to mimic. In addition, the tricuspid annulus is large and may dilate over time. Some reports show that the Melody devices, which are round, may be prone to early valve failure after implantation in the tricuspid valve (Catheter Cardiovasc Interv 2013;82[3]:428-435).

“Putting a round valve in a crescent is quite different,” William O’Neill says. “To try to put a premanufactured valve in there is going to be tough. How that valve interacts with the right ventricle and the wall of the right ventricle is going to be tough.”

Placing a round valve in the IVC circumvents those problems because the IVC also is round. “The earliest approach is going to be in the IVC junction,” he predicts. “I think that will work a lot better and be more durable.”

Still, suitable candidates will need to have an IVC diameter of 29 mm or less to accommodate the Sapien valve. “Although we still have size constraints, the diameter of the inferior vena cava is not as big as the tricuspid valve annulus,” Brian O’Neill says. “That will allow us to use the current valve technology.”

They hope that results from the pilot study will persuade a manufacturer to develop a device specifically for tricuspid regurgitation to replace Sapien valves, which can cost an estimated $30,000. As with TAVR, the price of the valve accounted for most of the expense of the tricuspid procedure at Henry Ford, according to William O’Neill. That price tag may deter insurers.

“Reimbursement will be trouble,” he says. “This patient had a good insurance company that was willing to pay for the procedure, but every patient will be a story at a time to see if his or her insurance carrier will pay.”