The body has its own solution to an inadequate blood supply caused by blocked or partially blocked arteries. When an artery is severely narrowed, the body can increase the amount of blood flowing to the heart muscle by opening up small branches of nearby arteries. Known as collateral circulation, these networks of blood vessels create new routes for blood to detour around clogged arteries.
The development of a collateral circulation is particularly important in the heart muscle where it may be life saving. However, the development of collateral circulation is a gradual process, and not everyone has the same ability to develop these networks. In a three year, follow-up study, the majority of patients remained free of angina and showed persistent improvements in their thallium scans