Affiliation:
1. Cardiovascular Research Institute, the Department of Pediatrics, and the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, Department of Surgery, University of California, Los Angeles, California 90014
Abstract
The accuracy of regional myocardial blood flow measurements made with microspheres of different sizes is uncertain. Therefore, we simultaneously injected radioactive microspheres of different sizes into the left atria of dogs and sheep; the microsphere diameters were 25µ, 15µ, 9µ, 1-l0µ, and filtered 1-10µ (most > 7µ). Antipyrine was sometimes simultaneously infused for 15-60 seconds. Myocardial blood flow was altered by hemorrhage, tachycardia, supravalvar aortic constriction, or infusion of methoxamine or adenosine triphosphate; left coronary artery branches were occluded on two occasions. Sometimes the percent of untrapped microspheres was estimated. All sizes of microspheres measured similar total myocardial blood flows when the percent of untrapped microspheres was known. All indicators were distributed identically to the right and left ventricular free walls and septum; ischemic areas had a 1% excess of antipyrine. With any pair of microspheres, the larger had a subendocardial excess except for 25µ microspheres, which were in excess compared with 15µ microspheres in the higher flow layer whether it was subendocardial or subepicardial. The greatest difference for any pair of microspheres was 10.53% of flow in a layer. Antipyrine did not define which size of microspheres measured true regional blood flow, since many previously unemphasized limitations were discovered. Nevertheless, we believe that microspheres 9µ in diameter are probably the best for measuring regional myocardial blood flow.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine,Physiology
Cited by
282 articles.
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