Study Shows the Heart Can Build Its Own Bypass After a Heart Attack

After a heart attack, the heart does more than simply endure the damage. New research suggests that tiny capillaries try to become artery-like vessels and create a natural bypass around the blocked artery.

A heart attack occurs when a coronary artery becomes blocked, cutting off oxygen and nutrients to the heart muscle. The organ activates several emergency mechanisms, including widening existing arteries and creating new ones. Earlier research found that these responses are usually too slow or too weak to prevent serious damage or death.

Researchers from the University of the Chinese Academy of Sciences have now identified another part of this response. Their study, published in Science, used a more precise cell-tracking technique to follow endothelial cells, which line blood vessels. The researchers observed these cells in both large arteries and the much smaller capillaries connecting arteries and veins.

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These findings change the current understanding of the cellular origin and mechanism of coronary collateral blood vessel formation and highlight their role in effective heart recovery.

In mice that had suffered induced heart attacks, the smaller capillaries did most of the work involved in redirecting blood flow. They appeared to transform into vessels more similar to arteries, in a process resembling the development of the hearts of newborn mice. The researchers said the findings change existing views of the cellular origin and mechanism behind coronary collateral vessels.

The team then tested whether it could strengthen the process. Short-term treatment with carefully calibrated doses of the growth-signaling protein VEGF-A triggered chemical reactions that improved the development and function of the new bypass vessels. Treated mice showed better blood flow around the damaged area, less heart scarring and improved heart function. The researchers said moderate VEGF-A supplementation also restored microcirculation, pointing to the possibility of targeting the vessel environment in future treatment.

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This process resembles a developmental program in which capillary endothelial cells join together to form small-diameter coronary artery branches during heart development in newborns.