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At least 1,009 records · Page 56Linked to original sources
PubMed2000

Relationship of vascular maturation in breast cancer blood vessels to vascular density and metastasis, assessed by expression of a novel basement membrane component, LH39.

Angiogenesis, the formation of new vessels, has been demonstrated to be an indicator of prognosis in breast cancer patients. The extent of differentiation of the tumour vessels may affect access of peripheral white cells and egress or invasion of tumour cells. This has not been assessed in relation to tumour microvessel density or other variables and may be a marker of vascular remodelling. LH39 is a monoclonal antibody recognizing an epitope located at the lamina lucida of mature small veins and capillaries but not in newly formed vessels. To study vascular differentiation in breast tumours, we examined the vascular maturation index (VMI) in 12 normal and 50 breast carcinomas and this was correlated with different clinicopathological variables including angiogenesis. Mature vessels were defined by staining with antibodies to both LH39 and to CD31, using double immunohistochemistry, whereas immature vessels stained only for CD31. VMI was defined as the % fraction of mature vessels (LH39-positive) / total number of vessels (CD31-positive). The VMI was significantly higher in normal (54-68.5%; median 66.5%) than in tumours (0-47%; median 8.8%) (P = 0.0005). There was a significant inverse correlation between the tumour VMI and nodal status (Fisher's exact test, P = 0.01) and between high VMI and low thymidine phosphorylase (TP) expression (Mann-Whitney U-test, P= 0.01). No significant association between VMI and tumour size, oestrogen receptor, epidermal growth factor receptor, grade, angiogenesis, patient age, or E-selectin was seen. There was a significant reduction in relapse-free survival (P = 0.01) with high angiogenesis. These findings show that the VMI gives new information on the mechanism of tumour angiogenesis independently from microvessel quantitation, there is a wide variation in the differentiation of tumour vasculature but the degree of capillary differentiation is not associated with quantitative angiogenesis. The VMI identifies a subset of patients who have a high chance of regional node involvement.

Adult↗
PubMed2002

[Fasciocutaneous radial artery perforator vessels - an anatomic study].

PURPOSE/BACKGROUND: Distal and proximal pedicled forearm flaps that are nourished by radial perforator vessels have been described. These flaps spare the radial artery during flap harvest. The question is, whether it is possible to raise individual free fasciocutaneous radial perforator flaps. METHOD AND MATERIAL: The number, external vessel diameter, and distribution of fasciocutaneous radial perforator vessels were investigated on 20 fresh cadaver arms. All specimen were then treated with the Spalteholz technique to demonstrate the arborizing of the perforator vessels. RESULTS: There was an average of 12 (range 9 to 16) fasciocutaneous perforator vessels per radial artery. The most proximal perforator vessel had an external diameter of 0.8 (range 0.5 to 1.0) mm, the others were measured smaller then 0.5 mm. There was a rich network of anastomoses at the level of the fascia up to the level of the subdermal plexus. CONCLUSIONS: The anatomic basis of the proximally and distally based radial perforator flaps was confirmed. Free flaps based exclusively on fasciocutaneous radial perforators would require supra-microsurgical skills due to the small vessel diameter. For practical reason it seems to be advisable to include parts of the radial artery into such a flap design.

Humans↗
PubMed1991

Safety of vessel ligation in laparoscopic surgery.

Laparoscopic ligaturing entails the use of the Roeder knot which is fashioned outside the abdomen, slipped along the ligature to the intended site and locked in place. The safety of the one-way Roeder slip knot in securing blood vessels and the tension a vessel ligature has to withstand were investigated ex vivo. Ligature tension was measured using perfused blood vessels in a test rig. From these data the ligature tension exerted by vessels up to 3 mm diameter at 150 mm Hg pressure was observed to be less than 5 grams. The relationship between ligature tension (T) and intravascular pressure (p), radius of the vessel (r) and radius of the vessel at the point of ligature (delta) is expressed by the formula: T = 3/2 pr delta. A good correlation between values for ligature tension derived from this formula and those observed in the test rig confirmed the validity of this equation for the calculation of approximate ligature tension. Catgut sutures tied with Roeder knots were subjected to strain gauge distraction under different conditions. The tension required to induce reverse slipping of the Roeder knot fashioned from 0/chromic catgut had a median value of 1125 (225-2700) grams weight. Thus in laparoscopic surgery the Roeder knot with dry chromic catgut has a substantial safety factor ratio of 55:1 in ligation of vessels up to 3 mm diameter.

Blood Pressure↗
PubMed1994

[Fine structure of conjunctival lymphatic vessel valves].

BACKGROUND: Lymphatic valves are due to ensure a zentripetal flow of lymph. The majority of the authors regard these valves as bicuspid structures with joint insertion points of the downstream localized free valvular edges. Because of that valvular structure a retrograde flow of lymph is impossible. Observations of our own however demonstrated retrograde flow of fluid under physiological conditions. In the following paper the structure of conjunctival lymphatic valves should be investigated or rather those structures, which were regarded as valves hitherto. Are there segmental connections, which allow retrograde flow of lymph? Is a regulation of lymph flow possible without self-acting valves? MATERIALS AND METHODS: In the conjunctiva of bovine post-mortem eyes (n = 100) segmental connections of lymphatic vessels with a diameter of less than 1 mm were opened specifically under control of slit lamp microscope after having undertaken an interstitial double contrast lymphography (solution of Berliner Blue/air). Some of these preparations (n = 20) could be investigated further on with the scanning electron microscope. That procedure allowed to make the patterns of flow and vessels structures in the beginnings of the lymphatic system observed with the slit lamp microscope congruent with those structures shown by the scanning electron microscope. RESULTS: The following segmental connections could be demonstrated: 1. Lymphatic vessels, which flow like a pipe into the wall of another segment. 2. Laterally arranged oval connections with valve resembling an aperture. 3. Segments of lymphatic vessels arranged in a line, which flow into one another between two hump-shaped protrusions with bicuspid valvular structures. Also the existence of different connecting structures ("valves") in one segment ("gear segment") were observed. In bulbus-like segmental connections arranged one behind the other with two valvular leaflets it could be demonstrated by scanning electron microscopy, that the two leaflets were attached apart at the vessel wall. That divergence to the previous models of lymphatic valves means, that these valvular leaflets cannot work as self-acting valves and prevent retrograde flow. CONCLUSIONS: However according to the valveless model of Libau a directed regulation of flow is possible. Perhaps the valvular structures described above play an important part by the interaction between the endothelium of lymphatic vessels and the substances transported in the lymph. The variety of segmental connections, the network of vessels with different diameters, which seem to be connected by feed-back, demand a new way of looking at the initial lymph flow.

Animals↗
PubMed2000

Mosaic blood vessels in tumors: frequency of cancer cells in contact with flowing blood.

The presence of "mosaic" vessels in which both endothelial cells and tumor cells form the luminal surface has profound implications for metastasis, drug delivery, and antivascular therapy. Yet little is known of the frequency, and thus importance, of mosaic vessels in tumors. Using CD31 and CD105 to identify endothelial cells and endogenous green fluorescent protein labeling of tumor cells, we show that approximately 15% of perfused vessels of a colon carcinoma xenografted at two different sites in mice were mosaic vessels having focal regions where no CD31/CD105 immunoreactivity was detected and tumor cells appeared to contact the vessel lumen. These regions occupied approximately 25% of the perimeter of the mosaic vessels, or approximately 4% of the total vascular surface area in these colon carcinomas. In addition, we found similar numbers of mosaic vessels in human colon carcinoma biopsies. Our results are consistent with the observation that approximately 10(6) cells are shed daily per g of tumor. More importantly, our data offer a possible explanation for the antivascular effects of cytotoxic agents and suggest potential strategies for targeting the tumor vasculature.

Animals↗
PubMed1999

Effect of craniopharyngioma fluid on femoral vessels of rat.

Craniopharyngioma fluid spillage during surgery is reported to cause aseptic meningitis, but effects of the spillage on vessels have not yet been studied. Therefore we experimentally studied the effect of external contact on femoral vessels of the rat to assess its possible role in the cerebral vascular complications. The major direct effect of the craniopharyngioma fluid on the femoral vessels was vasospasm, appearing on the fourth day after instillation. The vasospasm was observed in 83% of femoral vessels studied between 4-15 days and one of the vessels showed intra-luminal thrombus. The difference in the vessel diameter after instillation (4-15 days) was compared with the controls and was statistically significant (p < 0.01). These findings correspond well with the observed deterioration on post-operative days 5-7, due to vascular complications. No histopathologic (light-microscopic) changes of inflammation or necrosis were found in the femoral vessels. Our study shows that contact of craniopharyngioma fluid to arteries leads to vasospasm, and spillage during surgical excision may contribute to vascular complications encountered in the post-operative period. Prevention of spillage of this fluid and the routine use of cerebral vasodilators to prevent ischemic complications after craniopharyngioma surgery needs further evaluation.

Animals↗
PubMed2004

Evaluation of ST-segment changes during and after maximal exercise tests in one-, two- and three-vessel coronary artery disease.

OBJECTIVE: To relate ECG and heart rate (HR) variables during and after exercise testing with the presence of one-, two- or three-vessel disease defined by angiography. DESIGN: Seventy-three male patients with stable angina pectoris and angiographically verified coronary artery disease underwent a maximal exercise test. From 12-lead ECG recordings and computer averaging ST-amplitude and HR data were measured in consecutive 10-s intervals. RESULTS: In univariate analysis, patients with three-vessel disease had lower maximal exercise capacity, a shorter time to >1 mm ST-depression, more often a clockwise ST/HR recovery loop, more frequently a post-exercise downward ST-segment slope, and a greater ST-deficit at 3.5 min after exercise than patients with one-vessel disease. In multivariate analysis, time to >1 mm ST-depression discriminated between patients with three- and one-vessel disease. In patients with an intermediate time to >1 mm ST-depression a clockwise ST/HR recovery loop and/or a downsloping ST-segment in the post-exercise period were significantly more prevalent in severe vessel disease. CONCLUSION: Patients with three-vessel disease had a significantly shorter time to >1 mm ST-depression during exercise and more often an abnormal post-exercise ST/HR reaction than those with one-vessel disease.

Adult↗
PubMed2004

A prototype vessel compressor helps efficient laser treatment of small leg veins.

The eradication of small leg veins with lasers continue to present problems. Visible light lasers (488 nm approximately 595 nm) are well absorbed in haemoglobin but melanin is also a target, necessitating aggressive skin cooling to prevent damage to the epidermis and adding to the expense of these laser systems. A new generation of much less expensive semiconductor-based lasers operating in the near infrared offers a different approach, with protein as the main target rather than pigment. For visible light lasers, compression of the target vessels is a contraindication, since the target pigment is removed. For near IR diode lasers, however, compression of the vessels is a benefit, as the cooling effect of the blood flow is removed and the highly proteinous vessel walls are coapted which encourages efficient coagulative vessel closure. The prototype of a simple vessel compressor is presented, which first compresses vessels and coapts the walls, and then presents the coapted vessels as a target for a laser of an appropriate wavelength.

Humans↗
PubMed2001

Mathematical modelling of responses of cerebral blood vessels to changing intraluminal pressure.

The authors have designed a mathematical model to investigate the influences of the physical and chemical properties of the cerebral blood vessel resistance on vessel diameter. The model is based on the way the total tension within the blood vessel walls varies due to specific ions interacting and affecting the vascular smooth muscle cells and the vascular walls. In particular, we shall model a series of calcium sites and derive a generalized equation of the diameter as a function of pressure. The model includes the action of the vascular smooth muscle cells and the elasticity of the vascular walls, the pressure exerted on the walls by the blood and the effect of alterations to their properties within the blood vessel. They are formulated in terms of three parameters: the diameter at zero pressure, the myogenic response as the pressure tends to zero and a term associated with the myogenic tone. All three parameters may be reliably extracted from diameter-pressure measurements. The model was successfully used in quantifying diameter oscillations and dynamic myogenic responses that are frequently observed both in vivo and in vitro. Finally, we tested the model on experimental data obtained from the resistance of cerebral vessels that have been isolated from rats. In particular, we have first shown that the blood vessel characteristics are such that the diameter change due to calcium ion variations is at a maximum value. Second, we have shown that blood flow affects the myogenic response and third, we can explain the affect of ATP on the vessel diameter.

Adenosine Triphosphate↗
PubMed2002

The effect of surgery and severe injury on blood vessels.

This paper evolves from our previous work that developed a blood vessel model based on the way in which the total tension within the blood vessel wall varies with pressure due to the interaction of specific ions. We use the previous outcomes to examine the diameter of rat middle cerebral arteries (MCAs) as a function of pressure. The MCAs were isolated at 2 h, 1 and 5 days following sham injury and severe traumatic brain injury (TBI). First, we are able to quantify the diameter versus pressure curve in a way that yields three parameters. One of these parameters is the diameter at zero pressure that incorporates properties of the blood vessel walls and the vascular smooth muscle cells. The other two parameters are associated with the myogenic response and the myogenic tone. These parameters enable us to characterize, from the MCAs as a function of pressure in a calcium buffer, each blood vessel into one of three distinct distributions. One of these distributions reflects the optimum conditions. From our data with our blood vessel model, we demonstrate the effect of sham injury on the way in which blood vessels respond to pressure change that appears to recover over time with a half-life of about 40 h. In contrast, severe TBI greatly affects the blood vessel with no indication of recovery over the five-day monitoring period.

Animals↗
PubMed1996

Vessels around the ureteropelvic junction: significance and imaging by conventional radiology.

We studied the influence of vessels crossing the ureteropelvic junction and of the grade of hydronephrosis in 86 patients who underwent endoureteropyelotomy. With a follow-up ranging from 1 to 12 years, the presence of crossing vessels had a significant negative influence on the outcome and recurrence rate of the procedure. The success rate was 82% when no vessels were present but only 33% when crossing vessels were documented. In 13 of 15 failures (87%), a crossing vessel was found at open pyeloplasty. The degree of hydronephrosis was a less potent detrimental factor, with an 81% success rate in low-grade and 54% in high-grade hydronephrosis. The best results (90% success) were obtained in patients with no crossing vessels and low-grade hydronephrosis and the worst (30% success) in those with high-grade hydronephrosis in the presence of crossing vessels. Selection of patients according to those prognostic factors is recommended. Conventional intravenous urographic imaging techniques proved insufficient, and only angiography provided diagnostic accuracy; less-invasive methods are desirable.

Angiography↗
PubMed1999

Lymphatic vessel hypoplasia in fetuses with Turner syndrome.

Turner syndrome is associated with subcutaneous accumulation of fluid in the neck region that can be visualized sonographically from 10-14 weeks of gestation as massively increased nuchal translucency thickness. Possible mechanisms for this increased translucency include dilatation of the jugular lymphatic sacs because of developmental delay in the connection with the venous system, or a primary abnormal dilatation or proliferation of the lymphatic channels interfering with a normal flow between the lymphatic and venous systems. The aim of this study was to investigate the distribution of lymphatic vessels in nuchal skin tissue from fetuses with Turner syndrome compared with fetuses carrying trisomies 21, 18 and 13 and chromosomally normal controls. The distribution of vessels was examined by immunohistochemistry using a monoclonal antibody, PTN63, against 5' nucleotidase and an anti-laminin antibody. In normal control fetuses (n = 6) and those with trisomies 21 (n = 3), 18 (n = 2) and 13 (n = 2), PTN63-positive and laminin-positive vessels were evenly distributed throughout the dermis and subcutis. In Turner syndrome (n = 3), there was a chain of large vessels that stained with both PTN63 and laminin at the border between dermis and subcutis, but there was scarcity of vessels in the upper dermis and the subcutis. Using PTN63 alone, there were no positive vessels in the upper dermis. We conclude that in Turner syndrome lymphatic vessels in the upper dermis are hypoplastic.

Chromosomes, Human, Pair 13↗
PubMed2003

Vessel contents of leaves after excision: a test of the Scholander assumption.

When petioles of transpiring leaves are cut in the air, according to the 'Scholander assumption', the vessels cut open should fill with air as the water is drained away by tissue rehydration and/or continued transpiration. The distribution of air-filled vessels versus distance from the cut surface should match the distribution of lengths of 'open vessels', i.e. vessels cut open when the leaf is excised. A paint perfusion method was used to estimate the length distribution of open vessels and this was compared with the observed distribution of embolisms by the cryo-SEM method. In the cryo-SEM method, petioles are frozen in liquid nitrogen soon after the petiole is cut. The petioles are then cut at different distances from the original cut surface while frozen and examined in a cryo-SEM facility, where it is easy to distinguish vessels filled with air from those filled with ice. The Scholander assumption was also confirmed by a hydraulic method, which avoided possible freezing artefacts. In petioles of sunflower (Helianthus annuus L) the distribution of embolized vessels agrees with expectations. This is in contrast to a previous study on sunflower where cryo-SEM results did not agree with expectations. The reasons for this disagreement are suggested, but further study is required for a full elucidation.

Freezing↗
PubMed2004

Inhibitory effects of the anesthetics propofol and sevoflurane on spontaneous lymphatic vessel activity in rats.

BACKGROUND: The effects of propofol and sevoflurane on lymphatic vessel activity are unknown. This study aimed to clarify the effects of these anesthetics on lymphatic vessel activity in rats by the use of a technique for mechanical removal of the endothelium. METHODS: The authors first examined the effects of propofol (8 mg/kg) and sevoflurane (2.0%) on in vivo lymphatic flow by injection of dye into the femoral regions of rats. In the in vitro study, the ends of the vessel segments of rat thoracic duct were connected to a syringe and stopcock, respectively. Spontaneous changes in diameter of each segment were monitored, and the extraluminal side of each segment was exposed to propofol (1 x 10(-6) approximately 3 x 10(-5) M) or sevoflurane (0.5 approximately 2.0%). Endothelial function was eliminated by perfusion of air into the lumen. RESULTS: In the dye uptake study, 80% of iliac lymphatic nodes were positively stained in a control group, whereas only 10% and 20% were positively stained in propofol and sevoflurane groups, respectively. In the in vitro study, both of the anesthetics significantly decreased the amplitude of spontaneous activity of lymphatic vessels with or without endothelial function. Sevoflurane inhibited the frequency of lymphatic vessel activity but propofol had no effect on it. When the endothelial function was eliminated, both anesthetics decreased the frequency of spontaneous activity of lymphatic vessels. CONCLUSIONS: Propofol and sevoflurane seem to have some different effects on endothelial function, which regulates the pacemaking of spontaneous contraction of lymphatic vessels.

Acetylcholine↗
PubMed1993

Collateral perfusion through overlapping vessels reduces canine right ventricular ischemic injury from positive end-expiratory pressure.

OBJECTIVE: To test, in a canine model of right ventricular ischemia with 15 cm H2O positive end-expiratory pressure, whether collateral perfusion through overlapping vessels from the left ventricle to the right ventricular free wall can reduce infarct size. DESIGN: Randomized, prospective, controlled, experimental study in dogs. SETTING: Anesthesia research laboratory of an academic medical center. SUBJECTS: Twenty microfilaria-free mongrel dogs. INTERVENTIONS: Anesthetized, closed-chest dogs were managed with the application of 15 cm H2O positive end-expiratory pressure. The right coronary artery was ligated (90 mins) with occlusion (n = 10) and without occlusion (n = 10) of overlapping vessels. MEASUREMENTS AND MAIN RESULTS: Myocardial blood flow (using radioactive microspheres) was measured in the area at risk (gentian violet) and in the area of necrosis (triphenyltetrazolium chloride). With right coronary and overlapping vessel occlusion, blood flow in the area at risk decreased from 80.1 +/- 14.0 to 9.0 +/- 1.7 mL/min/100 g after 5 mins of ischemia (p = .0001) and remained depressed at 8.7 +/- 1.8 mL/min/100 g after 75 mins of ischemia. With right coronary occlusion alone, blood flow decreased after 5 mins of ischemia from 64.8 +/- 5.4 to 14.3 +/- 1.9 mL/min/100 g (p = .0001 compared with baseline), which was 60% greater than the group with occluded collateral vessels (p = .0055). Moreover, after 75 mins of ischemia, blood flow in the area at risk increased further to 28.9 +/- 5.4 mL/min/100 g with patent overlapping vessels (p = .0001 compared with 5-min value). The patency of overlapping vessels during right ventricular free wall ischemia reduced the area at risk from 68.5 +/- 2.4% to 38.6 +/- 5.1% (p = .0001) and the area of necrosis/area at risk from 58.1 +/- 8.4% to 16.9 +/- 3.6% (p = .0007). CONCLUSIONS: Despite 15 cm H2O positive end-expiratory pressure, perfusion through overlapping vessels improved peri-ischemic blood flow in the area at risk, thereby reducing the size of the risk area and the amount of right ventricular free wall necrosis.

Animals↗
PubMed1994

Variability of response to atrial natriuretic peptide and sodium nitroprusside in cultured vascular smooth muscle cells from three blood vessels.

OBJECTIVES: Vascular beds vary in their responses to atrial natriuretic peptide and sodium nitroprusside. Both of these agents dilate blood vessels by increasing intracellular guanosine 3',5'-cyclic monophosphate (cyclic-GMP) but activate different enzymes in the vascular smooth muscle cell. We aimed to determine if the response of intracellular cyclic-GMP to atrial natriuretic peptide and sodium nitroprusside varies in smooth muscle cells cultured from different vascular beds. DESIGN: Prospective, repeated measures analysis of concentration-response curves. SETTING: Anesthesia research laboratory of an academic medical center. SUBJECTS: Guinea pigs: Cultured guinea pig smooth muscle cells were obtained from three different blood vessels. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Intracellular cyclic-GMP was measured by radioimmunoassay and concentration-response curves of cyclic-GMP to atrial natriuretic peptide and sodium nitroprusside were determined. Cells from the thoracic aorta were the most responsive to atrial natriuretic peptide. Atrial natriuretic peptide (1 microM) increased cyclic-GMP concentrations to 72 +/- 5 pmol/mg (20-fold increase) with a 50% effective concentration of 3 nM. The concentration-response curve in epicardial coronary smooth muscle cells was to the right with an 50% effective concentration for atrial natriuretic peptide of 20 nM and a maximum response of a ten-fold increase in cyclic-GMP. Coronary resistance vessel cells were unresponsive to atrial natriuretic peptide. In response to sodium nitroprusside, the concentration-response curve in coronary resistance vessel cells was significantly to the left of either thoracic aorta cells or the epicardial coronary cells. The 50% effective concentration for sodium nitroprusside in coronary resistance vessel smooth muscle cells was approximately 1 microM, while in both thoracic aortic cells and epicardial coronary cells, the 50% effective concentration was ten times higher. Coronary resistance cells were the most responsive with a 62-fold increase in cyclic-GMP in response to 1 mM of sodium nitroprusside. The maximum response in thoracic aorta cells and epicardial cells was 20- and 30-fold, respectively. CONCLUSIONS: Smooth muscle cells respond differently to vasodilators. The response of these cultured cells mimics the response of the intact vascular bed from which they were obtained. These findings suggest that phenotypic properties of smooth muscle cells within a blood vessel contribute to the responsiveness of the vessel.

Analysis of Variance↗
PubMed1990

Automated tracking and computer reproduction of vessels in DSA images.

We are developing an automated vessel-tracking method based on the double-square-box region-of-search technique, for efficient tracking of the connected vascular tree in a digital subtraction angiography (DSA) image. Tracking points and branch vessels are located by searching of the perimeter of boxes, which are centered on previously determined tracking points. The most accurate results (90% true-positive rate with six false-positives per image) are obtained by tracking using the double-square-box method. In relatively straight regions of vessels, a large box is employed for efficient tracking; in curved regions of vessels, a small box is employed to ensure accurate tracking. When tracking is completed, accurate vessel information, ie, the vessel position, size, and contrast determined at each tracking point, is available for further quantitative analysis. Computer reproductions of tracked vessel trees appear to correspond well to those in DSA images.

Angiography, Digital Subtraction↗
PubMed1994

Color Doppler ultrasound of changes in small vessel diameter and cerebral blood flow during acute anemia in the newborn lamb.

RATIONALE AND BACKGROUND: The relationship between changes in small vessel diameter as determined by arteriography and those estimated by color Doppler ultrasound were tested. These techniques were used to examine the effects of acute isovolemic anemia on cerebral blood flow and small vessel diameter in the newborn lamb. MATERIALS AND METHODS: Validation of Doppler measurements was obtained in two lambs. Color Doppler diameter estimates of the anterior tibial artery (1-2 mm) were compared with simultaneous arteriographic measurements during vasodilatation and vasoconstriction effected by intra-arterial infusions of papaverine and norepinephrine, respectively. Acute anemia was produced in five newborn lambs by serial isovolemic exchange transfusions with adult sheep plasma. Doppler estimates of intracranial vessel diameter and mean blood flow velocity were correlated with simultaneous cerebral blood flow (CBF) determinations corrected for cerebral oxygen consumption (CBF/CMRO2). RESULTS: In the anterior tibial artery, color Doppler measurements of vessel diameter correlated well with arteriographic measurements (r2 = .77, P = .001), but overestimated the absolute vessel diameter by 10% to 27%. Hemodilution resulted in significant increases in CBF/CMRO2 (r2 = .61, P = .001), and estimated diameter of small cerebral arteries (r2 = .93, P = .001). Percent change in mean blood flow velocity correlated well with changes in CBF/CMRO2, but underestimated true changes in blood flow by approximately 40% (r2 = .93, P = .0001). Conversely, changes in Doppler volume flow overestimated true change in flow by approximately 50% (r2 = .84, P = .0001). CONCLUSIONS: Under certain physiological conditions, small cerebral arteries may make an important contribution to the overall regulation of CBF. Doppler estimates of relative flow and vessel diameter correlate well with true changes in CBF and small vessel diameter.

Acute Disease↗