Coronary steal
Encyclopedia
Coronary steal is a phenomenon where an alteration of circulation patterns lead to a reduction in the blood directed to the coronary circulation
. It is caused when there is narrowing of the coronary arteries 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 ischaemic zones, creating more ischaemia.
. Hence, dipyridamole is a pharmacological success, but a therapeutic failure because of the coronary steal phenomenon.
Coronary steal is also the mechanism in most drug-based cardiac stress test
s; 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.
In is also associated with the administration of Isoflurane, which is an inhaled anesthetic. Hydralazine can potentially cause this condition as well, as it is a direct arteriolar vasodilator.
It has been associated with nitroprusside.
It can also be associated with new patterns of blood vessel growth.
Coronary circulation
Coronary circulation is the circulation of blood in the blood vessels of the heart muscle . The vessels that deliver oxygen-rich blood to the myocardium are known as coronary arteries...
. It is caused when there is narrowing of the coronary arteries 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 ischaemic zones, creating more ischaemia.
Causative agents
It is associated with dipyridamoleDipyridamole
Dipyridamole is a drug that inhibits thrombus formation when given chronically and causes vasodilation when given at high doses over a short time.-Mechanism and effects:...
. Hence, dipyridamole is a pharmacological success, but a therapeutic failure because of the coronary steal phenomenon.
Coronary steal is also the mechanism in most drug-based cardiac stress test
Cardiac stress test
Cardiac stress test is a test used in medicine and cardiology to measure the heart's ability to respond to external stress in a controlled clinical environment....
s; 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.
In is also associated with the administration of Isoflurane, which is an inhaled anesthetic. 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.It can also be associated with new patterns of blood vessel growth.