What physiological effect does dipyridamole have on myocardial supply?

Dipyridamole primarily acts as a vasodilator, which can lead to an increase in blood flow to certain areas of the heart. However, in the context of patients with coronary artery disease, dipyridamole-induced vasodilation can also result in a phenomenon called "coronary steal." This occurs when blood flow is redirected away from areas supplied by the already narrowed coronary arteries toward regions with less compromised circulation. Consequently, the effective myocardial supply can be reduced in these affected areas, which is particularly concerning during stress testing or in the presence of existing ischemic conditions.

This reduction in effective blood supply, especially in compromised areas of the myocardium, is a key factor in understanding how dipyridamole works during cardiovascular assessments. It helps clinicians gauge the severity of coronary artery disease, making it an important tool in the evaluation of myocardial perfusion. Therefore, while dipyridamole can induce an increase in overall myocardial blood flow, the localized effect it can have in patients with existing ischemic heart conditions leads to a decrease in effective myocardial supply in the areas that need it most.