Determination of coronary flow reserve by parametric imaging.

Abstract

Nine mongrel dogs were instrumented with electromagnetic flow probes (EMF) to measure coronary blood flow through the left anterior descending (LAD) and left circumflex (LCx) coronary arteries at rest and after maximal coronary vasodilation (1 mg/kg/min adenosine). Relative coronary blood flow was determined by parametric imaging in the left posterior oblique projection using digital subtraction angiography (DSA). Transmural myocardial perfusion of the LAD and LCx beds was determined with tracer-labeled microspheres. Coronary flow reserve (maximal coronary blood flow divided by resting blood flow) was calculated under control conditions and after constriction of the proximal LAD or LCx by a screw occluder. Heart rate decreased significantly from 140 beats/min at rest to 122 beats/min after adenosine (p<0.001) and from 134 (rest) to 120 beats/min (adenosine; p<0.05) after coronary constriction. Peak systolic pressure was kept constant with an aortic constrictor. Left ventricular end-diastolic pressure increased significantly from 18 mm Hg at rest to 23 mm Hg (p<0.05) after coronary constriction. At baseline, coronary flow reserve was 4.2 with DSA, 3.8 with EMF, and 3.7 with microspheres; after coronary constriction,it was 2.6 (DSA), 1.9 (EMF), and 1.5 (microspheres) (all p<0.001 versus baseline). Coronary blood flow showed a good correlation between EMF and microspheres (r=0.87,p<0.001), with a standard error of estimate (SEE) of 0.78 ml/g/min.

A new angiographic method to assess coronary flow reserve—Validation in humans

“…This approach was based on measuring the mean transit time (MTT) by calculating the time difference of the contrast between two ROIs in an artery and proved to be reliable only within proximal vessel segments. Other groups computed the MTT between the two ROIs, known as timing parameters methods [8, 14–17]. All of these methods were based on a rather simple morphological analysis of the TDC and did not address the complex physiologic characteristics of the TDC [18, 19].…”

Prognostic role of aortic atherosclerosis and coronary flow reserve in patients with suspected coronary artery disease

“…Coronary flow reserve (CFR) is defined as the ratio of maximal (stimulated) to baseline (resting) coronary blood flow and is used to assess epicardial coronary stenoses and to examine the integrity of microvascular circulation [1,2]. Both vasodilator transoesophageal (TEE) and transthoracic echocardiography can be used for the evaluation of coronary flow velocity changes in the left anterior descending (LAD) coronary artery [1,3].…”