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Noninvasive assessment of coronary collaterals in man by PET perfusion imaging
L L Demer1, K L Gould, R A Goldstein
1Division of Cardiology, University of Texas Medical School, Houston.
Insights
Positron emission tomography (PET) can non-invasively identify coronary collateralization in patients with coronary artery disease (CAD). This method detects "coronary steal," a fall in blood flow during vasodilation, which is linked to developed collaterals.
Area of Science:
- Cardiology
- Medical Imaging
- Physiology
Background:
- Coronary collateralization is crucial for myocardial perfusion in coronary artery disease (CAD) but cannot be assessed non-invasively.
- In animal models, coronary collaterals are linked to coronary steal, a phenomenon where vasodilation reduces regional blood flow.
Purpose of the Study:
- To investigate the effect of pharmacologic coronary vasodilation on collateral bed perfusion in humans.
- To determine if positron emission tomography (PET) can non-invasively identify coronary collateralization in patients with CAD.
Main Methods:
- Myocardial perfusion imaging using PET with 82Rb or 13N ammonia was performed.
- Patients underwent imaging at rest and during pharmacologic vasodilation (dipyridamole/handgrip stress).
- 28 patients with angiographic collaterals and 25 control patients with similar CAD severity were studied.
Main Results:
- A decrease in regional myocardial activity (indicating coronary steal) was observed in 25 of 28 patients with collaterals.
- Only 4 of 25 control patients without collaterals showed this effect.
- Developed collaterals were significantly associated with myocardial steal.
Conclusions:
- Developed coronary collaterals are associated with myocardial steal in patients with CAD.
- PET imaging during vasodilation can potentially identify coronary collateralization non-invasively.
- This technique may offer a new diagnostic tool for assessing collateral function in CAD.
Abstract:
At present, coronary collateralization cannot be identified or assessed noninvasively in patients. In animal studies, coronary collaterals are associated with coronary steal, defined as a regional fall in perfusion during coronary arteriolar vasodilation. To determine the effect of coronary arteriolar vasodilation on collateral bed perfusion in man, myocardial perfusion imaging was performed before and after pharmacologic coronary vasodilation in patients with coronary artery disease (CAD). Regional myocardial activity of 82Rb or 13N ammonia was measured by positron emission tomography (PET) at rest and with intravenous dipyridamole/handgrip stress in 28 patients with angiographic collaterals and in 25 control patients with similar CAD severity by quantitative arteriography. Regional myocardial activity decreased after dipyridamole, indicating coronary steal, in 25 of 28 patients with angiographic collaterals and in only 4 of 25 control patients without angiographic collaterals. These findings suggest that developed collaterals are associated with myocardial steal in patients with CAD, allowing potential use of PET for non-invasive identification of coronary collateralization.