Hybrid tissue-engineered valves may expand options for heart valve surgery patients

S. Hamed Alavi, PhD, and Arash Kheradvar, MD, PhD, from the University of California in Irvine, developed the potentially revolutionary hybrid tissue-engineered heart valve.

Current valve replacement options are limited to those made solely from manufactured products (mechanical valves) or animal tissue (bioprosthetic valves). Mechanical heart valves tend to last longer than bioprosthetic valves, but they carry a greater long-term risk for blood clots that may lead to stroke and arterial thrombosis (clotting in the arteries), as well as bleeding from anticoagulant medications designed to prevent thrombosis.

"Bioprosthetic valve replacements, on the other hand, are prone to limited durability, which means patients may need a reoperation usually 10 to 15 years after implantation," said Dr. Alavi.

Traditionally, tissue-engineered valves are built on a scaffold that will degrade once the tissue is more mature. Once the scaffold has degraded, however, the valve leaflets often shrink, which can cause leaks and result in valve failure.

"For our research, we decided to use a non-degradable scaffold that stays within the valve to provide the support it needs without interfering with its normal function," said Prof. Kheradvar. "The valve we created uses an ultra-flexible scaffold made of an alloy of nickel and titanium (Nitinol) that is enclosed within the patient's own cultured tissue. The entire process takes about 3 to 8 weeks."

The researchers said that they expect the hybrid valve to self-regenerate inside the body, eventually incorporating itself into the patient's heart structure. By using the patient's own cells, the valve will become a "living" replacement for the diseased valve.

"We believe this new hybrid technology will significantly improve a patient's quality of life by eliminating the need for lifelong medications and without compromising the durability of the valve," said Dr. Alavi. "This is particularly beneficial for younger patients who are in need of a heart valve replacement."

The researchers have completed initial lab testing and now plan to initiate the next phase of trials. If all goes well, they anticipate the hybrid heart valve will be available for use in patients in 5 to 10 years.