TY - JOUR
T1 - The role of capillaries in determining coronary blood flow reserve
T2 - Implications for stress-induced reversible perfusion defects
AU - Kaul, Sanjiv
N1 - Funding Information:
From the Cardiovascular Imaging Center, Cardiovascular Division, University of Virginia School of Medicine, Charlottesville, Va. Supported in part by grants (3R01-HL48890, RO1-HL65704, and RO1-HL66034) from the National Institutes of Health, Bethesda, Md. Reprint requests: Sanjiv Kaul, MD, Cardiovascular Division, Box 158, Medical Center, University of Virginia, Charlottesville, VA 22908; sk@virginia.edu. J Nucl Cardiol 2001;8:694-700. Copyright © 2001 by the American Society of Nuclear Cardiology. 1071-3581/2001/$35.00 + 0 43/1/119690 doi:10.1067/mnc.2001.119690
PY - 2001
Y1 - 2001
N2 - In summary, unlike tracers such as radiolabeled microspheres that are trapped in the microcirculation (and therefore have a 100% extraction fraction), the uptake of diffusible tracers is determined by the status of myocardial capillaries. When the coronary arterioles and venules are fully dilated, the ceiling of hyperemia CBF (or CBF reserve) is determined by the capillaries in the absence of coronary stenosis. When a coronary stenosis is present, its resistance is only partially responsible for the attenuation of the hyperemic response. During hyperemia, the capillaries derecruit distal to a stenosis in order to maintain a constant hydrostatic pressure, which is the main reason for the reduced CBF reserve seen in the presence of coronary stenosis. This derecruitment results in a decrease in capillary surface area, which causes reduced extraction of the isotope and the consequent perfusion defect. The degree of capillary derecruitment distal to the stenosis during hyperemia is proportional to stenosis severity. It is for this reason that the presence, extent, and magnitude of reversible perfusion defects have such strong prognostic value.
AB - In summary, unlike tracers such as radiolabeled microspheres that are trapped in the microcirculation (and therefore have a 100% extraction fraction), the uptake of diffusible tracers is determined by the status of myocardial capillaries. When the coronary arterioles and venules are fully dilated, the ceiling of hyperemia CBF (or CBF reserve) is determined by the capillaries in the absence of coronary stenosis. When a coronary stenosis is present, its resistance is only partially responsible for the attenuation of the hyperemic response. During hyperemia, the capillaries derecruit distal to a stenosis in order to maintain a constant hydrostatic pressure, which is the main reason for the reduced CBF reserve seen in the presence of coronary stenosis. This derecruitment results in a decrease in capillary surface area, which causes reduced extraction of the isotope and the consequent perfusion defect. The degree of capillary derecruitment distal to the stenosis during hyperemia is proportional to stenosis severity. It is for this reason that the presence, extent, and magnitude of reversible perfusion defects have such strong prognostic value.
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U2 - 10.1067/mnc.2001.119690
DO - 10.1067/mnc.2001.119690
M3 - Article
C2 - 11725266
AN - SCOPUS:0035215838
SN - 1071-3581
VL - 8
SP - 694
EP - 700
JO - Journal of Nuclear Cardiology
JF - Journal of Nuclear Cardiology
IS - 6
ER -