[Diagnostic role of biopsy of the superficial temporal artery in Horton's temporal arteritis].
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Perfusion of the juxtapapillary retina and the neuroretinal rim area in primary open angle glaucoma.
PURPOSE: The objective of this study is to evaluate capillary blood flow of the juxtapapillary retina and neuroretinal rim area in primary open angle glaucoma (POAG) by a new noninvasive method performing a high-definition topography of perfused vessels of the retina and the optic nerve head with simultaneous evaluation of blood flow. METHODS: Juxtapapillary retinal and neuroretinal rim area blood flow were measured by scanning laser Doppler flowmetry (SLDF). This new technique is a combination of a laser Doppler flowmeter with a scanning laser system by which the retinal perfusion is simultaneously quantified in 16,000 sites of a retinal area of 2.7 x 0.7 mm. In study I, retinal and optic nerve head blood flow were evaluated by SLDF in 43 patients with POAG and 43 healthy individuals. The mean age of the POAG group was 56 +/- 12 years and of the control group 42 +/- 15 years. In study II, age-matched normals (n = 21) were compared with glaucoma eyes with topical therapy (n = 30) and with glaucoma eyes without topical therapy (n = 16). RESULTS: In study I, the eyes with POAG had an average cup/disc ratio (C/D) of 0.75 +/- 0.20, with an average mean defect of the visual field of 5.3 +/- 5.4 dB. The actual intraocular pressure was 17.8 +/- 4.18 mm Hg in the POAG group and 15.45 +/- 1.82 mm Hg in the control group. For statistical analysis, two age-matched groups of 28 normal eyes of 28 persons with 27 glaucomatous eyes of 27 patients were compared. In normals the blood flow of the neuroretinal rim area was significantly higher than that of the juxtapapillary retinal area (+7.73%, p < 0.01). In POAG both juxtapapillary retinal blood flow and neuroretinal rim area blood flow were significantly decreased compared to an age-matched control group: neuroretinal rim area flow -71% and juxtapapillary retina flow -49%. The decrease of neuroretinal rim area blood flow did significantly correlate with C/D. We found no correlation between reduction of juxtapapillary retinal blood flow and C/D or mean defect. Both glaucoma eyes with and glaucoma eyes without topical therapy showed significant decreased juxtapapillary blood flow compared to normals. We found no significant difference in the juxtapapillary blood flow between glaucoma eyes with and without topical therapy. CONCLUSIONS: In POAG, optic nerve head blood flow and juxtapapillary blood flow were significantly decreased.
Adult↗
Principle, validity, and reliability of scanning laser Doppler flowmetry.
PURPOSE: The objective of this study is to present the reliability and validity of scanning laser Doppler flowmetry (SLDF) performing a high-definition topography of perfused vessels of the retina and the optic nerve head with simultaneous evaluation of blood flow. METHODS: The examination of blood flow by SLDF is based on the optical Doppler effect. The data acquisition and evaluation system is a modified laser scanning device; the wavelength of the laser source is 670 mm, with a power of 100 microW (Heidelberg Engineering, HRF). The reliability of SLDF was estimated by performing five separate measurements in 10 eyes on 5 days. The validity of the method was tested by two experiments. First, in an experimental set-up, the capability of SLDF to measure the velocity of a moving plane in absolute units was estimated. Second, comparative measurements were performed of retinal blood flow in normal eyes and in 33 glaucomatous eyes with SLDF and a commercially available single-point laser Doppler flowmeter (Oculix). RESULTS: We found SLDF to produce a high reliability. The reliability coefficients r1 of flow, volume, and velocity were 0.82, 0.81, and 0.83, respectively. Comparative measurements of the retinal blood flow by SLDF and a single-point laser Doppler flowmeter of corresponding retinal points showed a linear and significant relationship between flow (r = 0.83, p < 0.0001), volume (r = 0.51, p < 0.0001), and velocity (r = 0.59, p < 0.0001). In the experimental set-up, SLDF was able to quantitatively measure velocity in absolute units. CONCLUSIONS: SLDF enables the visualization of perfused vessels of the juxtapapillary retina and the optic nerve head in high resolution by two-dimensional mapping of the optical Doppler shift and a reproducible evaluation of capillary blood flow.
Evaluation Studies as Topic↗
Optic nerve head circulation after topical calcium channel blocker.
PURPOSE: Our purpose was to investigate the effects of the calcium channel blocker verapamil on intraocular pressure and blood circulation in the human optic nerve head. METHODS: The effects of three different concentrations of topical verapamil (0.063%, 0.125%, and 0.25%) on intraocular pressure and optic nerve head capillary blood speed were measured in 12 healthy normal subjects. In a randomized, double-masked design, each subject received one drop of either verapamil or placebo in one eye and the opposite treatment in the fellow eye. Anterior optic nerve circulation was assessed at baseline and 90 min after instillation of the drops using the laser Doppler technique. RESULTS: The intraocular pressure was significantly reduced compared with baseline in both verapamil- and placebo-treated eyes at each concentration. The reductions of intraocular pressure were greater in verapamil-treated eyes (12-17%) than in placebo-treated eyes (9-12%). No systemic effect on heart rate or blood pressure was detected after administration of topical verapamil. The capillary blood speed in the optic nerve head was increased in both verapamil- and placebo-treated eyes at each concentration, although the only statistically significant increases were with the 0.25% concentration. The mean +/- SEM increase compared with baseline at the 0.25% concentration was 10.4 +/- 3.6% in verapamil-treated eyes (p = 0.017), and 11.6 +/- 4.4% in placebo-treated eyes (p = 0.026). CONCLUSIONS: These results indicate that topical administration of verapamil lowers the intraocular pressure and increases the capillary blood speed in the optic nerve head in normal subjects. Changes measured in verapamil-treated eyes were also observed in placebo-treated eyes, indicating a crossover effect.
Administration, Topical↗
Estimating mechanical blood trauma in a centrifugal blood pump: laser Doppler anemometer measurements of the mean velocity field.
A laser Doppler anemometer (LDA) was used to obtain the mean velocity and the Reynolds stress fields in the inner channels of a well-known centrifugal vaneless pump (Bio-pump). Effects of the excessive flow resistance against which an occlusive pump operates in some surgical situations, such as cardiopulmonary bypass, are illustrated. The velocity vector field obtained from LDA measurements reveals that the constraint-forced vortex provides pumping action in a restricted area in the core of the pump. In such situations, recirculating zones dominate the flow and consequently increase the damage to blood cells and raise the risk of thrombus formation in the device. Reynolds normal and shear stress fields were obtained in the entry flow for the channel formed by two rotating cones to illustrate the effects of flow disturbances on the potential for blood cell damage.
Blood Flow Velocity↗
Coronary microcirculation during left heart bypass with a centrifugal pump.
To estimate coronary microcirculation during left heart bypass (LHB), we performed an experimental comparison study of LHB and intraaortic balloon pumping (IABP). LHB was performed with a BioMedicus BP-80 pump supporting half of the flow of cardiac output whereas the IABP was pumped in a 1:1 mode for cardiogenic shock in a swine model. Coronary circulations were analyzed by electromagnetic flowmeter, pulsed Doppler velocimeter, and laser Doppler flowmeter. Left ventricular end-diastolic pressure (LVEDP) was reduced significantly by LHB. Although there was no significant difference in epicardial flow between the LHB and IABP groups, endo cardial flow was increased significantly by LHB. In the LHB group, the systolic reverse wave of the coronary velocity called a myocardial invalid circulation was reduced remarkably. There was a significant inverse correlation between endocardial flow and LVEDP. These results suggested that LHB was more effective for myocardial microcirculation than was IABP.
Animals↗
Relationship of thallium-201 clearance on exercise stress myocardial scintigraphy to coronary flow reserve in patients with coronary artery disease.
OBJECTIVE: We evaluated thallium-201 (201Th) clearance measurement during exercise myocardial scintigraphy in patients with coronary artery disease, for the assessment of coronary circulatory function and diagnosis. DESIGN: The clearance rate of 201Th was compared with the coronary flow reserve measured by Doppler coronary flow velocimetry. METHODS: We selected 20 patients who had chronic stable angina with single-vessel coronary artery disease of the left anterior descending artery (LAD) and underwent percutaneous transluminal coronary angioplasty (PTCA). Ten control patients had atypical chest pain but no detectable heart disease. Regional net clearance of 201Th was measured from the early and delayed bull's-eye images of 201Th exercise stress single photon emission tomography (SPECT). Using a Doppler catheter, we also measured coronary flow reserve of the LAD, which was obtained by the intracoronary administration of papaverine. RESULTS: The net 201Th clearance in the anterior wall myocardium in the patients with coronary artery disease before PTCA was significantly less than that in the controls. At follow-up angiography after successful PTCA, it increased. The coronary flow reserve before PTCA was also lower than that in the controls. It was increased immediately after PTCA, and was more markedly increased at the follow-up angiography. Before PTCA, regional net clearance in the anterior myocardium was correlated with the coronary flow reserve of the LAD. The ratio for the net clearance of the anterior myocardium at follow-up angiography to that before PTCA was also correlated with the ratio for coronary flow reserve. CONCLUSIONS: In patients with coronary artery disease, the regional 201Th clearance in the ischaemic area measured by exercise 201Th SPECT is correlated with the coronary flow reserve of the affected artery. Moreover, the increase in the clearance rate after PTCA is also correlated with that in the coronary flow reserve. Thus the measurement of regional 201Th clearance might be a useful non-invasive method of estimating of the coronary flow reserve.
Analysis of Variance↗
Role of adenosine in blood flow in the rat intestine.
We examined the relation between adenosine production and increased blood flow. For this purpose, we used a sensor holding system with a laser Doppler blood flowmeter. The elevation of blood flow was observed by administration of adenosine. Therefore, when AMP was administered to the rats, the elevation of blood flow rate was observed. These results suggest that AMP is rapidly transported to the adenosine active site by ecto-5'-nucleotidase.
5'-Nucleotidase↗
Comparison of magnetic resonance imaging and Laser Doppler Anemometry velocity measurements downstream of replacement heart valves: implications for in vivo assessment of prosthetic valve function.
BACKGROUND AND AIM OF THE STUDY: The non-invasive, in-vivo assessment of prosthetic valve function is compromised by the lack of accurate measurements of the transvalvular flow fields or hemodynamics by current techniques. Short echo time magnetic resonance imaging (MRI) may provide a method for the non-invasive, in vivo assessment of prosthetic valve function by accurately measuring changes in the transvalvular flow fields associated with normal and dysfunctional prosthetic valves. The objectives of these in vitro experiments were to investigate the potential for using MRI as a tool to measure the complex flow fields distal to replacement heart valves, and to assess the accuracy of MRI velocity measurements by comparison with Laser Doppler Anemometry (LDA), a gold standard. METHODS: The velocity fields downstream of tilting disc, bileaflet, ball and cage, and pericardial tissue valves were measured using both three-component LDA and MRI phase velocity encoding under a steady flow rate of 22.8 l/min, simulating peak systolic flow. The valves were tested under normal and stenotic conditions to assess the MRI capabilities under a wide range of local flow conditions, velocities and turbulence levels. A new short echo time MRI technique (FAcE), which allowed velocity measurements in stenotic jets with high turbulence, was tested. RESULTS: Good overall agreement was obtained between the MRI velocity measurements and the LDA data. The MRI velocity measurements adequately reproduced the spatial structure of the flow fields. In most cases peak velocities were accurately measured to within 15%. CONCLUSIONS: The results indicate that the FAcE MRI method has the potential to be used as a diagnostic tool to assess prosthetic valve function.
Aortic Valve↗
The use of enzyme activated milk for in vitro simulation of prosthetic valve thrombosis.
BACKGROUND AND AIM OF THE STUDY: Thrombosis remains a serious risk for patients with artificial heart valves and may be attributed in part to adverse blood flow patterns. Although the final assessment of a valve must follow years of clinical experience, in vitro flow analyses give valuable information prior to implantation. Laser Doppler velocimetry and computational fluid dynamics enable quantitative flow analyses to be made in vitro. Whilst these techniques highlight features such as areas of stasis, turbulence and high shear which may predispose to thrombus formation, the complex and time varying nature of the flow through valves makes it difficult to predict accurately potential sites of thrombus deposition and accumulation. METHODS: A technique is described which uses enzyme activated milk as a coagulable blood analogue to indicate flow related clotting. Milk flowing past a test valve or object was activated to clot downstream of the test piece after a certain time period. Milk clot was deposited clot at sites determined by the local flow disturbances. Milk clotting patterns produced on and around standard objects were compared with the transient flow patterns predicted around identical configurations to test the validity of computational flow analyses for predicting flow disturbances leading to clotting. Milk clots on valves were compared with examples of thrombus found on explanted valves of the same design. RESULTS: The sites of deposition were consistent with the predicted flow patterns around the two configurations of flow obstruction studied. Milk clotting patterns on valves corresponded with the early stages of thrombus on explanted valves of the same design. CONCLUSIONS: Whilst a coagulable milk mixture may be used to evaluate the risk of flow induced clot adherence, care must be taken when extrapolating to the clinical situation as other factors such as material properties, blood chemistry and concomitant disease must also be considered.
Animals↗
Prostaglandin E1 ameliorates decreased tracheal blood flow after esophagectomy and aggressive upper mediastinal lymphadenectomy for esophageal carcinoma.
BACKGROUND: Aggressive upper mediastinal lymphadenectomy contributes to a better survival rate after esophageal resection to treat esophageal carcinoma, but it also increases postoperative respiratory complications. Devascularization of the airways because of mediastinal dissection is considered to be a cause of respiratory dysfunction. The present study attempts to clarify whether or not tracheal blood flow (TBF) deteriorates after esophagectomy and, if so, whether or not intravenous prostaglandin E1 (PGE1) attenuates the deterioration. STUDY DESIGN: Patients undergoing esophagectomy and aggressive upper mediastinal lymphadenectomy for the treatment of esophageal carcinoma (EC group, n = 12) or abdominal surgery (control group, n = 6) were enrolled in this study. Measurement of TBF was performed using a laser Doppler flowmeter. Changes in TBF induced by surgery and postoperative intravenous PGE1 were studied in both groups. RESULTS: The TBF deteriorated significantly in the EC group (21.78 +/- 9.60 to 11.24 +/- 4.45 mL/minute/10(-1) kg, p = 0.002) but did not change in the control group (26.13 +/- 6.84 to 26.61 +/- 4.69 mL/minute/10(-1) kg, p = 0.7371). Postoperative intravenous PGE1 partially, but significantly, reversed the deterioration in TBF in the EC group (11.53 +/- 4.58 to 14.87 +/- 6.30 mL/minute/10(-1) kg, p = 0.0207) but did not effect the control group (29.41 +/- 7.89 to 29.41 +/- 8.79 mL/minute/10(-1) kg, p = 0.9989). CONCLUSIONS: Esophagectomy and aggressive upper mediastinal lymphadenectomy cause a deterioration in TBF that is partially attenuated by PGE1.
Alprostadil↗
[Skin circulation--measurements with laser-doppler].
The change in the skin blood flow (SkBF) due to vasoconstriction or vasodilation of the cutaneous vessels is a thermoregulative response during cold or heat stress, respectively. SkBF is estimated in different ways, for instance by measuring body and skin temperature, by venous occlusion plethysmography or by radioactive xenon 133 clearance. The application of laser light based on Doppler shift is a relatively new method for SkBF measurement. At present, several companies operating throughout the world produce laser-Doppler flowmeters. The laser-Doppler method is designed particularly for cutaneous tissues and it facilitates monitoring of the blood flow, however, the measurement results are relative. Depending on the wavelength, the laser light penetrates into the tissue at different depths (from 0.6 to 1.5 mm). The laser light with the wavelength of 632.8 nm enables the measurement of thermoregulative and nutritional blood flow in the skin. The range of the measurement and application of the device provide an opportunity for developing a universal standard. The European Community has published a guide for laboratory quality assurance aimed at improving the standard of measurement records.
Body Temperature Regulation↗
Urinary bladder blood flow changes during the micturition cycle in a conscious pig model.
PURPOSE: To develop a method using laser Doppler flowmetry in conscious pigs, which allows the accurate simultaneous measurement of cystometric and cardiovascular parameters together with changes in vesical blood flow. The animal model was then used to investigate the changes in blood flow in the urinary bladder which occur during the micturition cycle. MATERIALS AND METHODS: Seven large white female pigs were subjected to chronically implanted vascular access and urodynamic catheters as well as an intramural vesical laser Doppler probe. The animals underwent repeated conscious urodynamics with simultaneous measurement of cardiovascular, urodynamic and vesical blood flow parameters. RESULTS: The model shows both compliant and low-compliance behavior and allows greater investigation of the effects of intravesical pressure on blood flow. Blood flow is not altered, during compliant filling and voiding transiently decreases flow to 38% of resting levels, with a rapid return to normal. Low-compliance filling results in a progressive fall in blood flow to a minimum of 45% of normal. At all times an inverse relationship between intravesical pressure and blood flow is maintained. CONCLUSIONS: The pig model proved to be well suited to the experimental conditions and provided reproducible results. The principal determinant of blood flow within the wall of the bladder is the pressure within its lumen. During normal filling the blood supply of the bladder is able to adapt to the large increase in surface area which occurs, maintaining blood flow until the pressure increases.
Animals↗
Effect of a short course of indomethacin on gastric mucosal blood flow using endoscopic laser-Doppler velocimetry.
OBJECTIVE: To assess the effect of a short course of indomethacin on gastric mucosal blood flow (GMBF). METHODS: Patients with musculo-skeletal pain of recent origin and were prescribed a short course of therapy with indomethacin (25 mg tid for 7 days) were studied Baseline measurements of GMBF were carried out using endoscopic laser-Doppler velocimetry prior to starting indomethacin. At sites on the antrum, incisura, lesser and greater curvatures, and fundus. GMBF measurements were repeated after indomethacin therapy, as above and also on sites of erosions, it any. RESULTS: Baseline GMBF at sites on the antrum, incisura, greater and lesser curvatures, and fundus were (mean) 8.6, 7.9, 8.8, 8.5 and 8.7 volts, respectively. Post-therapy values did not differ from the corresponding baseline values (8.7, 8.5, 8.6, 8.6 and 8.3 volts, respectively). However, ten of the 16 patients developed gastric mucosal erosions and the mean GMBF on these sites of erosion was significantly reduced (6.6 +/- 1.3 volts, p < 0.05). CONCLUSIONS: A short course of indomethacin therapy produces a patchy decrease in blood flow in the gastric mucosa and erosions were seen in these areas.
Adult↗
Influence of endotoxemia on hepatic energy metabolism in rats with obstructive jaundice.
BACKGROUND/AIMS: A secondary insult in patients with obstructive jaundice can lead to multiple system organ failure. We evaluated the influence of endotoxin on hepatic energy metabolism and hepatic tissue blood flow in obstructive jaundiced rats. MATERIAL AND METHODS: Male Sprague-Dawley rats were divided into a control group, an endotoxin administration group, an obstructive jaundice group, and an obstructive jaundice with endotoxin administration group. To evaluate hepatic energy metabolism, we have measured arterial blood ketone body ratio, and arterial blood total ketone body concentration. Hepatic tissue blood flow was determined by laser Doppler velocimetry. RESULTS: In the endotoxin administration group, no change was observed in hepatic energy metabolism. However, the obstructive jaundice group was associated with decreased hepatic tissue blood flow shortly after the outset of jaundice, while no change was observed in hepatic energy metabolism until 3 weeks later. In the obstructive jaundice with endotoxin administration, a significant decrease in hepatic tissue blood flow and an increase in hepatic energy metabolism were measured. CONCLUSION: Endotoxin administration alone had no influence on hepatic energy metabolism, while endotoxin administration in the presence of obstructive jaundice results in a rapid decrease in hepatic energy metabolism. This occurred as a result of the secondary insult of endotoxin in the setting of decreased hepatic tissue blood flow caused by obstructive jaundice.
Animals↗
[Microcirculatory changes in mitral prolapse as an expression of a systemic change in the connective tissue].
Many authors hypothesize that mitral valve prolapse (MVP) can be, in most cases, only a clinical sign of a primitive and systemic disorder of the connective tissue, like in Marfan Syndrome (MS). In our previous works we supported the presence of morphological and functional alterations of the microcirculation in patients affected by MS. In order to characterize a possible common denominator between these pathologies we have studied the cutaneous microcirculation in a group of patients affected by MVP, divided into 2 groups: anatomic MVP (MVP) and MVP syndrome (MVPS). The morphologic parameters have been investigated by nailfold capillaroscopy while digital laser-Doppler was used to study skin flowmetry. The results have been compared with a control group. Capillaroscopic remarkers showed an architecturally disorganized microvasculature with aspects related to a reduced compactness of the microvasculature unit with a significatively higher score compared with controls (7.3 +/- 2.9 vs 3.6 +/- 1 p less than 0.0005). Laser-Doppler flowmetry showed a significatively reduced rest flow; ischemic test showed: spike time 48.9 +/- 36.9 vs 15.3 +/- 7.7 s (p less than 0.0005), hyperemic acme 6.6 +/- 2.7 vs 12.5 +/- 8.4 UP (p less than 0.002); % increase 32.1 +/- 20.2 vs 51.5 +/- 15.4 (p less than 0.002). Thermic test showed a significatively higher thermic acme 8.7 +/- 4.2 vs 12.6 +/- 9.11 UP (p less than 0.05). These results appeared to be correlated with stage pathology as it was observed a severe microvasculature disorders in MVPS. Therefore we suppose that a phenotypic continuum may exist between MS and MVP.
Adult↗
Effects of neural blockade and general anesthesia on the laser-Doppler skin blood flow waves recorded from the finger or toe.
Effects of neural blockade and general anesthesia on the basic wave (BW) and the reflex wave (RW) among the laser-Doppler (L-D) skin blood flow waves recorded on the finger or toe were studied in 2 volunteers and 42 patients. The BW was continuous, rhythmic and independent of respiratory movements. The RW, which was induced by a deep inspiration or a snapping sound, was a transient marked reduction in blood flow. The BW was almost flattened and the RW was no longer induced at the finger under complete wrist block (n = 2), or under cervical or upper thoracic epidural anesthesia extended caudally over T7 (n = 2). On the other hand, the BW was still detected with reducing frequency and the RW could be provoked with one exception at the finger on the side with a sympathetic ganglion block at the C6 vertebral level (n = 14). The BW and RW at the toe were retained under lumbar subdural anesthesia (n = 6) as well. However, under the combination of lumbar subdural anesthesia and lower thoracic epidural anesthesia extending rostrally over T4 (n = 6), both the BW and the RW disappeared at the toe. In the course of deepening nitrous oxide/enflurane anesthesia (n = 10), the BW gradually reduced in frequency until it was almost flattened, and it became difficult to provoke the RW. L-D flowmetry of the finger or toe could be a useful clinical measure for detecting the presence or absence of sympathetic function controlling cutaneous vasomotion.
Adult↗
Current status of noninvasive tests in the diagnosis of peripheral arterial disease.
In this review of the current status of the vascular laboratory, the major emphasis has been upon those tests that have become well-established and documented, including resting pressure, pulse volume measurements, velocity studies, and three stress measurements--exercise ankle pressure, postocclusive reactive hyperemia, and the toe pulse reappearance time. Additional technology that may have application to peripheral arterial disease includes photoplethysmography, transcutaneous oxygen tension, laser-Doppler velocimetry, fluorescein angiography, infrared thermography, and transcutaneous electromagnetic flowmetry. These techniques, which are currently in development and experimental trial, were not discussed but are likely to provide significant additional information. The future role of the vascular diagnostic laboratory in the area of peripheral arterial occlusive disease appears clear. It has already become a standard resource of the community hospital and tertiary referral center. Its functions will become more and more generally accepted with time as newly graduating physicians who have been exposed to this technology enter the practice of medicine. It should permit obtaining an evaluation of all patients at the expert level, aid in the education of all physicians concerned with peripheral arterial disease, and play an important part in guaranteeing a higher level of patient care than has heretofore been available.
Arterial Occlusive Diseases↗