Coronary steal

Coronary steal (with its symptoms termed cardiac steal syndrome) is a phenomenon where an alteration of circulation patterns lead to a reduction in the blood directed to the coronary circulation.^[1] It is caused when there is narrowing of the coronary arteries and a coronary vasodilator^[2] 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 dipyridamole. Hence, dipyridamole is a pharmacological success, but a therapeutic failure because of the coronary steal phenomenon.^[3]

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.

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.^[4]

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.^[5]

It can also be associated with new patterns of blood vessel growth.^[6]

Treatment

It is sometimes treated by surgery.^[7]

See also

• Subclavian steal syndrome
• Vascular resistance

References

1. ^ Gould KL (August 1989). "Coronary steal. Is it clinically important?". Chest 96 (2): 227–8. doi:10.1378/chest.96.2.227. PMID 2787728. http://www.chestjournal.org/cgi/pmidlookup?view=long&pmid=2787728. 
2. ^ Werner GS, Figulla HR (July 2002). "Direct assessment of coronary steal and associated changes of collateral hemodynamics in chronic total coronary occlusions". Circulation 106 (4): 435–40. doi:10.1161/01.CIR.0000022848.92729.33. PMID 12135942. http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=12135942. 
3. ^ Essentials of Medical Pharmacology, 5th Edition
4. ^ David L. Hoyt; Wilson, William J.; Grande, Christopher M. (2007). Trauma. Informa Healthcare. pp. 304. ISBN 0-8247-2920-X. 
5. ^ Harrisson's Principles of Internal Medicine, 17th Edition
6. ^ Aziz S, Stables RH (July 2005). "Coronary steal induced by angiogenesis following bypass surgery". Heart 91 (7): 863. doi:10.1136/hrt.2004.043471. PMC 1768979. PMID 15958345. http://heart.bmj.com/cgi/pmidlookup?view=long&pmid=15958345. 
7. ^ Kern MJ (1996). "Coronary steal through anomalous internal mammary artery graft treated by ligation without sternotomy". Tex Heart Inst J 23 (4): 316–7. PMC 325384. PMID 8969040. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=325384.