An experimental "mini heart" could help people with a medical condition that causes blood to pool in their veins by pumping their blood through the vessels and back to the heart, researchers say.

The mini hearts are tiny pumps, consisting of a cuff of heart muscle cells. Once implanted to surround a vein, they could contract rhythmically, squeezing blood through the vessel. A patient's own stem cells could be used to make the mini heart, decreasing the chances of tissue rejection, researchers say.

"We can create a simple version of the heart, outside a person's own heart," and by placing it in the lower extremities, significantly improve blood flow through a person's veins, said Narine Sarvazyan, a pharmacologist and physiologist at George Washington University in Washington, D.C., who led the research published in the February 4 issue of the Journal of Cardiovascular Pharmacology and Therapeutics. [See Video of Mini Heart At Work]

In healthy veins, valves keep blood flowing in one direction, preventing blood from pooling and forming blood clots. But in people with vein disease, these valves stop functioning. About 25 percent of adults have varicose veins — twisted or swollen veins near the skin's surface — and 6 percent have a more serious version of the disease, according to studies.

Vein disease can lead to inflammation, ulcers, leg amputation and even death.

Although some treatments exist for diseased veins near the skin's surface, there are no effective treatments for problems with deep veins, Sarvazyan told Live Science.

Other researchers have sought to repair damaged hearts by growing beating heart tissue in the lab, and implanting it into the heart itself. In contrast, Sarvazyan's team took pieces of heart tissue and wrapped the pieces around veins.

To prevent the risk that the transplanted tissue will be rejected by the body, the team plans to grow the mini hearts using adult stem cells, which have the potential to transform into any type of tissue, from the patients themselves.

So far, the idea is only in the early testing phases in the lab, and has not been studied in living animals. First, the researchers plan to figure out the best designs for these mini hearts, and then they will try implanting them in rats and other animals, Sarvazyan said.

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