Coronary steal

Coronary steal, whose symptoms are called coronary steal syndrome or cardiac steal syndrome, is a phenomenon in which a change in blood circulation patterns reduces the blood flow reaching part of the coronary circulation. It occurs when a coronary artery is narrowed and a vasodilator medication is given, since the vessels downstream of the narrowed artery are already maximally dilated to compensate for reduced blood supply, so further dilation of resistance vessels elsewhere in the coronary circulation diverts blood away from the already oxygen starved area and worsens its condition.