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An initial foray into the ‘final frontier’ of percutaneous valve procedures—tricuspid valve replacement—suggests that a currently available pulmonary valve can feasibly be implanted in the tricuspid position, yielding few complications and good early valve function. The findings, from a small case series, were published in the July 5, 2011, issue of the Journal of the American College of Cardiology.

Researchers led by Philip A. Roberts, MB, ChB, of the Royal Prince Alfred Hospital (Sydney, Australia), analyzed procedural and clinical data from 15 patients in whom the Melody percutaneous pulmonary valve (Medtronic, Minneapolis, MN) was implanted in the tricuspid position at 1 of 8 centers worldwide. Use of the Melody valve in this position is off-label, since the device was designed and approved for pulmonary valve replacement.

All patients had severe hemodynamic compromise and were symptomatic, with 1 subject graded as New York Heart Association (NYHA) class IV, 10 as class III, and 3 as class II. Moreover, the subjects were considered to be at high surgical risk, though all had undergone prior tricuspid surgery.

The primary indication for intervention was stenosis in 10 patients (mean gradient > 5 mm Hg) and regurgitation in 5 patients (moderate to severe tricuspid regurgitation and mean gradient of ≤ 5 mm Hg), although most had a mixed pathology. In 10 procedures the Melody valve was implanted into a dysfunctional bioprosthesis located in the normal tricuspid position, while in 5 it was inserted into a dysfunctional right atrium-to-right ventricle conduit in the setting of a functional single-ventricle palliative procedure.

Two Approaches to Delivery

The valve was delivered and deployed via the femoral vein in 11 patients and the right or left internal jugular vein in 4 patients. Predilation or low-pressure balloon sizing was performed prior to valve delivery in 4 cases. Postimplantation dilation using higher-pressure valvuloplasty balloons was done in 7 patients. The average procedure time was 120 ± 64 minutes and the average screening time was 29 ± 18 minutes.

After the procedure, the median tricuspid gradient was 2 mm Hg for all patients, while for those treated primarily for stenosis it was reduced from 12.5 mm Hg to 3.5 mm Hg (P < 0.01). No patient had more than mild residual regurgitation, and 10 had none as assessed by echocardiography. However, 1 patient with multiorgan failure prior to the procedure developed early progressive regurgitation and died 20 days after the procedure.

Other complications included 1 case of third-degree heart block requiring pacemaker implantation and 1 instance of Melody valve endocarditis requiring valve removal 2 months post-implant.

At latest follow-up (median 4 months; range, 0-38 months), 14 of the 15 patients were alive and well, with 13 retaining the Melody valve. NYHA class improved acutely in all but 2 of the surviving patients.

Still Many Unknowns

In a telephone interview with TCTMD, coauthor Doff B. McElhinney, MD, of Children’s Hospital Boston (Boston, MA), said, “We don’t yet have the data to say that [the percutaneous approach to tricuspid valve replacement] is safer than surgery, but I think it’s intuitive to believe that it might be in many patients.”

At this point, percutaneous replacement is not an alternative to surgery as the initial approach to tricuspid disease. “Generally this isn’t an option until you have some sort of [surgical] prosthesis to implant within,” Dr. McElhinney noted, although in certain anatomic circumstances, an initial percutaneous procedure is feasible.

A drawback specific to the Melody bioprosthesis is that the upper limit of the recommended implantable annulus size is 22 mm, which does not accommodate larger tricuspid valves, Dr. McElhinney said. For that reason, some researchers have turned to the larger Edwards Sapien valve (Edwards Lifesciences, Irvine, CA), he reported, adding, “Between the 2 [devices], you can cover a fairly wide range of bioprosthetic valve sizes.”

Because tricuspid valve replacement in general is relatively uncommon, it is difficult to gain experience with the percutaneous approach, Dr. McElhinney pointed out, although many of the technical aspects are similar to percutaneous procedures for other valves. Still, he noted, it is important to understand the tricuspid anatomy and to determine the appropriate implant site beforehand, because the valve be oriented at different angles. Knowing where any stenosis is and using predilation to relieve it also facilitates implantation.

‘Harbinger of Things to Come’

“This report is significant because it chronicles a measured step toward a new application for transcatheter valve technology,” writes John W. Moore, MD, MPH, of the University of California-San Diego (San Diego, CA), in an accompanying editorial that refers to the technology as a ‘game changer.’

Laying out the progress in the other valves, he observes, “It is fair to say that transcatheter valve technology will continue to advance, and will become a significant alternative to traditional valve surgery.” Thus, the current poof of principle for tricuspid replacement is “a harbinger of things to come,” he concludes.

Dr. Moore acknowledges, however, that, based on this limited series, “no definitive statements about the durability of [the Melody] valve in the tricuspid position, about efficacy, or about safety can be made.”

Dr. McElhinney agreed, saying that “the jury is still out on whether the benefit will be long-lasting,” but he added that in some cases the goal of percutaneous replacement may be palliative, or to allow a patient to improve enough clinically that surgery becomes possible.

Moreover, the functional longevity of the percutaneous valve likely will depend in part on the original pathology, which may involve high right ventricular pressure, Dr. McElhinney said, adding that the good news is additional valve-in-valve procedures may be feasible. “It all depends on size,” he said. “If you’re able to put in a large enough second valve that you don’t cause stenosis, then this is a great option. But the Melody valve is not expandable, and it takes up space.”

Looking at the larger picture, “[t]he territory of tricuspid valve disease and transcatheter therapy for it has lagged behind the other 3 valves,” Dr. McElhinney noted. “But tricuspid disease is important in a lot of different populations [including those with congenital and acquired disease], and it is the valve for which we probably have the least effective surgical options.

“As more good transcatheter therapies for managing tricuspid disease are developed, I think it’s potentially going to dramatically change how we think about several conditions that are now considered just too complicated or to have too poor a risk-benefit profile to try to improve,” he concluded.

Study Details

The median patient age was 31.5 years (range, 29-64 years).

A 22-mm Ensemble delivery system (Medtronic) was used in 14 patients; in the remaining patient a 24-mm BIB balloon (Numed, Hopington, NY) was employed because of the large diameter of the previously placed surgical valve and concern about achieving adequate apposition of the Melody valve.

2. Moore JW. Transcatheter valve technology: A game changer! J Am Coll Cardiol. 2011;58:123-124.

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