Relationship between regional myocardial blood flow and thallium-201 distribution in the presence of coronary artery stenosis and dipyridamole-induced vasodilation
This study assesses the relationship between the distribution of thallium-201 and myocardial blood flow during coronary vasodilation induced by intravenous dipyridamole in canine models of partial and complete coronary artery stenosis. 10 dogs were chronically instrumented with catheters in the left atrium and aorta and with a balloon occluder and electromagnetic flow probe on the proximal left circumflex coronary artery. Regional myocardial blood flow was measured during control conditions with radioisotope-labeled microspheres, and the phasic reactive hyperemic response to a 20-s transient occlusion was then recorded. Dipyridamole was then infused intravenously until phasic coronary blood flow increased to match peak hyperemic values. The left circumflex coronary artery was either partially occluded to reduce phasic blood flow to control values (group 1) or it was completely occluded (group 2), and thallium-201 and a second microsphere label were injected. 5 min later, the animals were sacrificed, the left ventricle was sectioned into 1-2-g samples, and thallium-201 activity and regional myocardial blood flow were measured. Curvilinear regression analyses between thallium-201 localization and myocardial blood flow during dipyridamole infusion demonstrated a slightly better fit to a second- as compared with a first-order model, indicating a slight roll-off of thallium activity as myocardial blood flow increases. During the dipyridamole infusion, the increases in phasic blood flow, the distributions of regional myocardial blood flow, and the relationships between thallium-201 localization and regional blood flow were comparable to values previously observed in exercising dogs with similar occlusions. These data provide basic validation that supports the use of intravenous dipyridamole and thallium-201 as an alternative to exercise stress and thallium-201 for evaluating the effects of coronary occlusive lesions on the distribution of regional myocardial blood flow.
- Research Organization:
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
- OSTI ID:
- 6748808
- Journal Information:
- J. Clin. Invest.; (United States), Vol. 73:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CORONARIES
BLOOD FLOW
DOGS
DRUGS
MICROSPHERES
MYOCARDIUM
THALLIUM 201
TISSUE DISTRIBUTION
VASODILATION
ANIMALS
ARTERIES
BETA DECAY RADIOISOTOPES
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
DAYS LIVING RADIOISOTOPES
DISTRIBUTION
ELECTRON CAPTURE RADIOISOTOPES
HEART
HEAVY NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MAMMALS
MUSCLES
NUCLEI
ODD-EVEN NUCLEI
ORGANS
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
THALLIUM ISOTOPES
VERTEBRATES
550901* - Pathology- Tracer Techniques