© 2003 by European Society of Cardiology
Copyright © 2003, European Society of Cardiology
Intramyocardial blood volume, perfusion and transit time in response to embolization of different sized microvessels
aDepartment of Physiology and Biophysics, Alfred 2-409, Mayo Clinic and Foundation, 200 First Street SW, Rochester, MN 55905, USA
bDepartment of Anatomic Pathology, Mayo Clinic and Foundation, Rochester, MN 55905, USA
cDivision of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA
dDepartment of Diagnostic Radiology, Mayo Clinic and Foundation, Rochester, MN 55905, USA
elran{at}mayo.edu
* Corresponding author. Tel.: +1-507-255-1939; fax: +1-507-255-1935.
Objective: To study the role of the coronary microcirculation in response to different-sized microemboli, we measured changes in intramyocardial microvascular blood volume (Bv), perfusion (F) and transit time (TT) and also microvascular patterns of injury. Methods: Bv, F and TT were quantitated in 24 pigs at baseline and again 2 min after repeat injections of 10- or 100-µm microspheres at rest or during intracoronary adenosine infusion. The association of Bv and TT was assessed in the microsphere pigs and in nine control pigs. Microvascular injury was studied on gross-pathologic and histologic samples. Results: At rest, initial injection of 10-µm microspheres led to increases in Bv and F, but progressively decreased with additional injections. In contrast, even small numbers of 100-µm microspheres always led to decreases in Bv and F. Injection of microspheres during adenosine-induced vasodilation always resulted in decreases in peak Bv and F irrespective of their diameters, but microvascular TTs remained unaltered. In control pigs, however, TTs were inversely related to adenosine-induced changes in Bv. Histologically, 100-µm microspheres resulted in patchy distribution of microcirculatory plugging, while 10-µm microspheres induced contiguous hemorrhagic myocardial injury. Conclusion: Microsphere-induced changes in intramyocardial Bv and F and the associated pattern of myocardial injury are related to the size of embolized microvessels and the initial perfusion state. Microvascular functional volume reserve mechanisms appear to play a key role accompanying flow- and TT-preservation.
KEYWORDS Bv, myocardial blood volume (ml g–1); F, myocardial perfusion (ml g–1 min–1); TT, transit time (s); EBCT, electron beam computed tomography
1 Present address. Department of Cardiology, University Clinic Essen, Hufelandstrasse 55, 45122 Essen, Germany.
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