Tiara Mitral Valve Replacement Passes Preclinical Study

A preclinical study to be published in the February issue of JACC: Cardiovascular Interventions  describes results of the implantation of Neovasc Inc.'s (Vancouver, BC, Canada) Tiara mitral valve device. Tiara is intended to be an alternative to open mitral valve repair or replacement for patients with mitral valve regurgitation who pose an unacceptable risk for surgery.

WebMD explains that mitral valve regurgitation means that the mitral valve, which lets blood flow from the upper to lower heart chamber, is letting blood leak backward into the heart. When the mitral valve is damaged it may no longer close tightly, which lets blood leak backward, or regurgitate, into the upper chamber. Small leaks are usually not a problem, but more severe cases weaken the heart and can lead to heart failure.

Tiara is a self-expanding bioprosthesis with cross-linked bovine pericardial tissue leaflets mounted inside a metal alloy frame and is designed to be implanted using the transapical approach. The study was conducted by researchers led by Shmuel Banai, MD, of the Tel Aviv Medical Center (Tel Aviv, Israel). The experimental valves were implanted in pigs, sheep, and human cadaver hearts. The sheep were followed for an average of 150 days following implantation and all remained clinically stable throughout that period.

Transcatheter mitral valve implantation "has the potential to become the preferred intervention to treat severe mitral regurgitation in patients who are at high risk for surgery, since it can theoretically reduce mitral regurgitation to an extent similar to that of surgery while preserving the mitral apparatus," the researchers reported.

Still, several challenges remain, the scientists say. "The ideal device must be stable and resistant to displacement or migration while enduring continuous cyclical movements of the mitral annulus and the base of the heart, as well as the high pressure gradients that are generated across the mitral valve," they observed, and valve materials must be "durable enough to withstand the loads generated."

Looking forward, the authors hope that "the results of the ongoing preclinical experiments of the Tiara valve will . . . lead the way to human clinical trials."