Regents’ Professor in mechanical engineering at Georgia Technology David Ku squeezes the prosthetic vein valve to the open position. The valve is intended to replace damaged or nonfunctioning valves. (Georgia Tech Photo: Gary Meek)

Engineers at the Georgia Institute of Technology have developed a prosthetic vein valve to help those suffering from chronic venous insufficiency, a condition in which valves in a person’s veins no longer ensures a flow of blood back to the heart. “Gravity lets blood flow to the toes, but the body uses vein valves to pump blood back to the heart,” says David Ku, the Lawrence P. Huang Endowed Chair in Engineering and Entrepreneurship at Georgia Tech.

“Vein valves occasionally dissolve after a blood clot,” says Ku. “The loss of valve leaflets lets blood flow the wrong way, causing swelling in the legs and ankles.” The condition affects more than seven million people in the U.S.

“Previous studies show that even implanting a donor valve can cause significant trauma to the patient’s leg,” adds Ku. “Other prosthetic valves have been designed to avoid these complications, but most demonstrate little clinical potential for humans.”

Ku and his collaborators believe the valve they have developed will overcome previous difficulties. The one-way flap is made of poly (vinyl alcohol) cryogel, a material patented by Georgia Tech in 1999. The biocompatible material can adjust its mechanical strength, has flexibility comparable to natural-body tissue, and it’s made of an organic polymer rather than silicone.

Preclinical animal trials have begun on sheep because their cardiovascular geometry and physiology are similar to humans. The animal trials follow several years of improving the valve design and testing it in the laboratory.

Initial lab tests show that the valve withstands pressures of more than 500 mm of mercury, yet opens with a pressure gradient of only 2.6 mm of mercury, which matches physiologic vein-valve function.