background and objective: the circle of willis (cow) supports adequate blood supply to the brain. the cardiovascular system, in the current study, is modeled using an equivalent electronic system focusing on the cow. method: in our previous study we used 42 compartments to model whole car- diovascular system. in the current study, nevertheless, we extended our model by using 63 compartments to ...

The objectives of this study were to assess the time course of enlargement and gene expression of a collateral vessel that enlarges following occlusion of the femoral artery and to relate these responses to the increases in collateral-dependent blood flow to the calf muscles in vivo. We employed exercise training to stimulate collateral vessel development. Rats were exercise trained or kept sed...

OBJECTIVE To investigate the hypothesis that the time to washout of radiographic contrast medium trapped distal to an occluded collateral receiving vessel is inversely related to collateral flow, and that this provides an accurate method for characterising coronary collaterals. METHODS An intracoronary pressure derived collateral flow index was determined in 54 patients undergoing percutaneou...

The formation of coronary collateral vessels is a compensatory mechanism secondary to repetitive or chronic myocardial ischemia. During the past three decades the functional and prognostic benefit of such collateral vessels has been established. There are large interindividual differences in the number and extent of collateral vessels that may be explained by differences in the anatomic situati...

AIMS To describe different patterns of retinal collateral circulation observed in normal subjects and in patients with a variety of ocular diseases during studies with the retinal functional imager (RFI). METHODS Normal subjects and patients with various ocular diseases underwent retinal blood flow imaging using the retinal functional imager. RESULTS Twenty-eight eyes of 21 patients constit...

This study was performed to test the hypothesis that active constriction of coronary collateral vessels can worsen hypoperfusion of collateral-dependent myocardium during exercise. Studies were performed in seven adult mongrel dogs in which intermittent followed by permanent occlusion of the left circumflex coronary artery produced an area of collateral-dependent myocardium without gross eviden...

BACKGROUND The extent of coronary collateral formation is a primary determinant of the severity of myocardial damage and mortality after coronary artery occlusion. Type 2 diabetes mellitus (T2DM) represents an important risk factor for impaired collateral vessel growth. However, the mechanism of reduced coronary collateralization in type 2 diabetic patients remains unclear. METHODS With the r...

BACKGROUND Coronary collateral flow is an alternative source of myocardial perfusion in patients with totally occluded coronary arteries. Clinical evaluation of collateral flow has been limited by the need of invasive measurements. We investigated whether noninvasive coronary computed tomographic angiography can evaluate the angiographic extent of coronary collateral flow. METHODS AND RESULTS...

The functional significance of coronary collateral flow from a nonobstructed supply artery was studied in 121 patients with severe (>80%) single-vessel disease, 64 with and 57 without Q wave infarction. All patients underwent exercise thallium imaging and coronary angiography. On angiography, collateral flow was present in 85% of 74 occluded arteries compared with only 17% of 47 arteries with s...

METHODS In 50 patients with oneand two-vessel coronary artery disease (CAD) undergoing percutaneous transluminal coronary angioplasty (PTCA), collateral flow index (CFI, no unit) changes and vascular resistance index (R, cm/mm Hg) changes of the collateral (Rcoll) and the distal collateral receiving (R4) vessel in response to adenosine (140 mg/min/kg IV) were measured by intracoronary (i.c.) Do...