Cardiac steal syndrome

Overview
Cardiac steal syndrome is a phenomenon caused when there is narrowing of the coronary arteries and an arteriolar vasodilator is used - "stealing" blood away from those parts of the heart. This happens as a result of the narrowed coronary arteries being always maximally dilated to compensate for the decreased upstream blood supply. Dilating the other arterioles causes blood to be shunted away from the coronary vessels.