Damaged Veins Heal Faster with Heparin Treatment

A commonly used medication that prevents blood clots from forming may also prevent existing clots from damaging delicate vein walls — and may accelerate healing in a clot-damaged area of vein wall, according to new research from the University of Michigan Cardiovascular Center.

The findings, made in laboratory mice, add more evidence to support the aggressive anti-clot efforts now under way at American hospitals and nursing homes. Those efforts are aimed at preventing many of the 300,000 deaths that occur each year when clots break free of vein walls and travel to the lungs.

The new study, published in the March issue of the Journal of Vascular Surgery, looked at the impact of low-molecular weight heparin, or LMWH, a form of anti-clotting medication that is often given to hospitalized patients. It’s different from the unfractionated form of heparin that has recently been the subject of safety concerns.

Researchers from the U-M Section of Vascular Surgery created venous clots in laboratory mice, and studied how the size of the clot, the damage inflicted on the vein wall, and the natural repair process in the cells of the vein wall changed over time. Some of the mice received LMWH before the clot was formed, while others received it afterward. Another group of mice received no heparin.

“Mice that received LMWH before their clot formed went on to experience a much faster and more complete healing process, compared with those that received LMWH only after the clot was formed and those that didn’t receive the drug,” says senior author Peter Henke, M.D., an associate professor of vascular surgery. “And among those that received LMWH only after the clot was formed, the mice that got treated the soonest after clot formation healed the fastest and the most completely.”

The experiments, performed in U-M’s Conrad Jobst Vascular Surgery Research Laboratory, simulated a human condition called deep-vein thrombosis, or DVT. That’s the term for blood clots that form in the veins of the lower limbs, clinging to and damaging the vein wall. When such clots break free and travel to the lungs, they’re called pulmonary embolisms or PEs.

A million Americans each year suffer DVTs, many of them during a hospital stay – and many of them without symptoms. About half go on to develop a PE, which causes sudden symptoms and must be treated immediately. Still, more than half of PE patients will die – making the condition one of the most preventable causes of death among hospitalized patients.

LMWH is increasingly prescribed to hospitalized patients who might be at risk of developing DVTs and PEs, especially older people, surgical patients, and people with a personal or family history of clotting problems. DVTs are especially likely to form in legs that are immobile for long periods of time, that have been injured, or that have poor circulation. Cancer patients, pregnant women, and overweight people are also at higher risk of developing one.