Coronary steal (with its

symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showi ...

s termed coronary steal syndrome or cardiac steal syndrome) is a phenomenon where an alteration of

circulation Circulation may refer to: Science and technology * Atmospheric circulation, the large-scale movement of air * Circulation (physics), the path integral of the fluid velocity around a closed curve in a fluid flow field * Circulatory system, a bio ...

patterns leads to a reduction in the blood flow directed to the

coronary circulation Coronary circulation is the circulation of blood in the blood vessels that supply the heart muscle (myocardium). Coronary arteries supply oxygenated blood to the heart muscle. Cardiac veins then drain away the blood after it has been deoxygenat ...

. It is caused when there is narrowing of the

coronary arteries The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ of ...

and a coronary 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. Thus, dilating the resistance vessels in the coronary circulation causes blood to be shunted away from the coronary vessels supplying the ischemic zones, creating more

ischemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems ...

Signs and symptoms

Mild coronary steal might not have any symptoms, but as the syndrome progresses, chest pain could usually be the first obvious symptom. In worse cases symptoms can include dizziness, flushing, headaches, nausea and shortness of breath

Cause

It is associated with

dipyridamole Dipyridamole (trademarked as Persantine and others) is a nucleoside transport inhibitor and a PDE3 inhibitor medication that inhibits blood clot formation when given chronically and causes blood vessel dilation when given at high doses over a ...

. Hence, dipyridamole is a pharmacological success diagnostically, but a therapeutic failure because of the coronary steal phenomenon. Coronary steal is also the mechanism in most drug-based cardiac stress tests; When a patient is incapable of doing physical activity they are given a vasodilator that produces a "cardiac steal syndrome" as a diagnostic procedure. The test result is positive if the patient's symptoms reappear or if ECG alterations are seen. Hydralazine can potentially cause this condition as well, as it is a direct arteriolar vasodilator. It has been associated with nitroprusside.

Other causes

Coronary arteriovenous fistula between coronary artery and another cardiac chamber, like, the coronary sinus, right atrium, or right ventricle may cause steal syndrome under conditions like myocardial infarction and possible angina or ventricular arrhythmias, if the shunt is large in magnitude.''Harrisson's Principles of Internal Medicine, 17th Edition'' It can also be associated with new patterns of blood vessel growth.

Diagnosis

Coronary steal syndrome can be diagnosed by: Electrocardiogram. Computed tomography angiogram. Coronary angiography. Stress testing with myocardial perfusion imaging

Treatment

It is sometimes treated by surgery.

References