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At least 757 records · Page 42Linked to original sources
PubMed1994

[Experimental research on choroidal circulation. 2. Choroidal blood flow increase elicited by electrical stimulation of parasympathetic nerve behind the eyeball in the cat].

The present studies were performed to examine whether the nerves behind the eye ball contain parasympathetic fibers which dilate the choroidal blood vessels. Choroidal blood flow in the cat (20 animals) was measured trans-sclerally with a laser Doppler flowmeter. Cats were anesthetized with pentobarbital sodium (30 mg/kg, i.v.) and artificially respirated after injection of pancuronium bromide (0.2 mg/kg/hr, i.v.). Electrical stimulation of the short ciliary nerve as well as of the nerve between the ciliary ganglion and accessory ciliary ganglion, where the sensory nerve is absent, elicited an increase choroidal blood flow in an intensity-dependent manner. Application of capsaicin, which is known to desensitize the polymodal nociceptive C-fibers, to these nerves did not abolish the increase in blood flow in response to electrical stimulation of the short ciliary nerve. Atropine, a muscarinic receptor antagonist, and phentolamine, an alpha-adrenoceptor blocking agent, had no effect on these responses. The results suggest that the blood flow increase elicited by stimulation of these nerves is mediated via activation of the atropine-resistant parasympathetic vasodilator fibers supplying the choroid in the cat.

Animals↗
PubMed1994

Effects of antihypertensive drugs on flow disturbances: nifedipine, captopril, and metoprolol evaluated by quantitative spectral analysis of Doppler flow patterns in patients with carotid stenosis.

Hemodynamic theories of atherogenesis suggest that flow disturbances (departures from laminar flow including high and low shear) and increases in heart rate may be important in the initiation, progression, and complications of atherosclerosis such as dissection and embolism. It is therefore desirable to evaluate the effects of antihypertensive drugs on the occurrence of such flow disturbances. Effects of metoprolol, nifedipine, and captopril were studied, by quantitative spectral analysis, in 20 patients with carotid stenosis to evaluate 3 indices of disturbed flow: peak velocity, spectral broadening index and window index (WI). Heart rate (HR), and the product of WI by HR, were improved (reduced) significantly by metoprolol (p < 0.05), and worsened by nifedipine (p < 0.05), but most of the effect was due to effects on heart rate. These findings suggest that most of the benefit of antihypertensive drugs on flow disturbances can be identified by counting heart rate. Further developments will require improved methods for quantitation of flow disturbances.

Aged↗
PubMed1994

[Use of the "color doppler" technique in diagnosing ovulation].

Graafian follicle growth and development and Doppler flow analysis of blood vessels in the wall of the follicle, was analyzed. Twelve patients with primary infertility were observed between days 12 to 15 of the cycle. Analysis of resistance index (RI) and pulsatility index (PI) of the wall vessels was performed. Statistically significant difference in RI and PI indices in preovulatory and post-ovulatory period was observed.

Female↗
PubMed1994

Hepatic microcirculatory perfusion failure is a determinant of liver dysfunction in warm ischemia-reperfusion.

Hepatic ischemia-reperfusion (I/R) is characterized by circulatory and metabolic derangements, liver dysfunction, and tissue damage. However, little is known about the causative role of I/R-induced microcirculatory disturbance on the manifestation of postischemic reperfusion injury. Therefore, the intention of the study was to assess changes of hepatic microvascular perfusion (intravital fluorescence microscopy) as related to hepatic morphology (light/electron microscopy), hepatocellular integrity (serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities), and excretory function (bile flow). Sprague-Dawley rats were subjected to 20 minutes (group B, n = 9) and 60 minutes (group C, n = 9) of left hepatic lobar ischemia followed by 60 minutes of reperfusion. Sham-operated animals without ischemia served as controls (group A, n = 10). Lobar ischemia for 20 minutes followed by reperfusion resulted in a significant reduction of sinusoidal perfusion rate (93.9 +/- 1.4%; P < 0.05) and a decrease in erythrocyte flux (90.0 +/- 5.6%) when compared with controls (99.4 +/- 0.2 and 97.9 +/- 2.7%). This was accompanied by a significant increase of serum AST and ALT activities (P < 0.05) and a reduction of bile flow (P < 0.05). Prolongation of lobar ischemia (group C, 60 minutes) aggravated postischemic reperfusion injury (sinusoidal perfusion rate: 87.4 +/- 2.9%; erythrocyte flux: 62.1 +/- 8.4%) and was paralleled by severed hepatocellular damage. Electron microscopy of postischemic tissue demonstrated alteration of nonparenchymal cells (swelling of sinusoidal lining cells and widening of Disse's space) and substantial parenchymal cell damage (swelling of mitochondria, disarrangement of rough endoplasmatic reticulum, vacuolization, complete cytoplasmic degeneration). Initial postischemic increase in serum AST and ALT activities and reduction of bile flow directly correlated with the extent of microcirculatory failure (P < 0.01), ie, impairment of sinusoidal perfusion and decrease of erythrocyte flux, indicating the decisive role of microvascular perfusion failure for the manifestation of hepatic tissue damage and liver dysfunction.

Alanine Transaminase↗
PubMed1994

In vitro fluid dynamic evaluation of the Carbomedics bileaflet heart valve prosthesis in the aortic and mitral positions.

Since the introduction of bileaflet heart valve prostheses their clinical use has continued to escalate. The first of this valve type was the Standard St. Jude Medical (SSJM) prosthetic heart valve in 1977. The Carbomedics prosthetic heart valve (CPHV), introduced in the late 1980s, was intended to improve on the design of the SSJM bileaflet valve. The design changes in the CPHV valve, relative to the SSJM valve, may have the potential to affect its flow fields. This study, using flow visualization laser Doppler velocity measurements and color Doppler flow mapping, was intended to evaluate how these changes affect the flow fields in the near vicinity of the CPHV valve. The study was conducted in an in vitro pulse duplicator system. In the flow visualization study, the flow fields observed with the CPHV valve were quantitatively similar to those seen with the SSJM valve. Centralized jet-like flows with flow separation/stagnation were observed in the illuminated planes. The jet-like flows from the two lateral orifices were broader than that observed from the central orifice for both the CPHV and the SSJM valves. This fact implied that the major part of the volumetric flow was through the two lateral orifices, rather than the central orifice. In the laser Doppler velocity measurements, it was found that the flow field downstream of the SSJM valve was slightly more evenly distributed than that with the CPHV valve. In addition, the extent of the flow separation regions with the CPHV valve were slightly larger than with the SSJM valve. The slight differences in velocity profiles between the SSJM and the CPHV valves were due to the differences in leaflet opening angle. However, the levels of flow turbulence with the CPHV and the SSJM valves were found to be of the same order of magnitude. The results of the flow visualization and LDA velocity and turbulence measurements obtained in the study indicate that the differences in flow fields in the immediate vicinity of the CPHV valve relative to the SSJM valve are insignificant.

Aortic Valve↗
PubMed1994

Low frequency oscillations of skin blood flux in peripheral arterial occlusive disease.

Using the laser Doppler technique patterns of spontaneous oscillations of skin blood flux within the low frequency band (< 10 min-1; LF waves) were analysed in 12 healthy controls and 24 patients with different degrees of peripheral arterial occlusive disease (PAOD). Measurements were performed at 5 different sites at the dorsum of the foot in healthy controls and patients with severe claudication or rest pain and/or gangrene due to PAOD. Patterns were classified as "periodic", "aperiodic" or "no flux motion". The aperiodic pattern was characteristic for skin blood flux of controls. In severe claudication prevalence of periodic LF oscillations significantly increased (p < 0.05) whereas it decreased again in patients with severe ischemia. In the latter group, LF waves often were completely absent. Periodic LF waves mainly occurred between an ankle/arm pressure ratio of 0.4 to 0.8. We suggest that periodic LF waves most likely ar the result of a synchronized vasomotor activity of different arterioles within the sample volume, whereas the aperiodic pattern may resemble the net effect of simultaneous activities of different control mechanisms on skin blood flow. Based on animal experiments it is hypothesized that decreased postocclusive driving pressure and flow in patients with advanced PAOD may be the stimulus for synchronized arteriolar vasomotion.

Adult↗
PubMed1994

[Study of cutaneous microcirculation using the laser-Doppler method in syndrome X].

Aim of the study was to verify the relationship between syndrome X and generalized microangiopathy. Three groups of patients were selected: Group A, 11 patients with typical syndrome X; Group B, 8 patients with atypical chest pain; Group C, 12 control normal subjects. Microvascular circulation was investigated with a laser Doppler Periflux PF3 at rest (15 min); during ischemia (3 min); during post-ischemic hyperemia on the plantar side of the big toe (where arterovenous anastomoses are particularly abundant) and on the dorsum of the foot (where these anastomoses are very scanty). During each recording we calculated: the mean flux value (FV); the mean concentration of moving blood cells (CMBC); the FV/CMBC ratio (which is related to the flow velocity); the mean percent increase of the three parameters during hyperemia. Patients with syndrome X as compared to the other subjects showed: 1) a significantly higher FV/CMBC ratio at rest and during hyperemia both on the plantar side of the big toe (respectively p = 0.01 and 0.015) and on the dorsum of the foot (respectively p = 0.011 and 0.006). These findings suggest a higher flow velocity in microvascular circulation; significantly lower percent increase of FV and CMBC during hyperemia in the plantar side of the big toe (respectively p = 0.04 and 0.014) but not on the dorsum. The increase of flow velocity at rest and low vasodilatatory reserve after ischemia in an area which is rich of arterovenous anastomoses in patients with syndrome X might be explained by the presence of a basal arterovenous hyperstomia.

Adult↗
PubMed1994

Retinal blood flow changes during pregnancy in women with diabetes.

PURPOSE: To study retinal blood flow (RBF) during pregnancy in subjects with and without diabetes and to relate the changes to progression in diabetic retinopathy. METHODS: RBF in a major temporal retinal vein was measured, where possible, during all three trimesters (T1 to T3) and the postpartum period (PP) using laser Doppler velocimetry (measuring velocity [V]) and monochromatic fundus photographs (measuring diameter [D]). RESULTS: In the subjects without diabetes (n = 19), no significant change in RBF was demonstrated. V was significantly greater in T3 than in PP (P = 0.01). D was significantly smaller in T1 to T3 than in PP (P < or = 0.01). RBF in the subjects with diabetes was significantly higher in T2 and T3 than in PP (P < 0.05). V increased from T1 to T2 (P = 0.04) and decreased from T2 to PP (P = 0.001) and from T3 to PP (P = 0.002). The only significant change in D was a smaller value in T1 than in PP (P = 0.003). However, it was only those subjects whose DR progressed (n = 11) who had a significant increase in RBF during pregnancy (P = 0.0001). CONCLUSIONS: These data suggest that the hyperdynamic circulation present in pregnancy led to compensatory retinal vessel constriction (autoregulation) in the group without diabetes; this was largely absent in the patients with diabetes, with resultant increase in retinal blood flow associated with worsening retinopathy. This finding lends further support to the hypothesis that increased retinal blood flow is a pathogenic mechanism for diabetic retinopathy.

Adult↗
PubMed1994

[Comparison of different monitoring techniques for vascular access in chronic hemodialysis].

Aim of the study was to compare different techniques of monitoring for vascular accesses in our chronic hemodialysis patients. Twenty seven patients (14 men, 13 women) were investigated. The accesses studied consisted of 19 arteriovenous fistulas and 8 vascular protheses. Twenty-four were trouble free, venous pressure was high in two, one was difficult to puncture. Three measurements of recirculation percentage were made for each patient, as well as a color Doppler flow imaging, and a digital angiography of the access. Recirculation measurements were normal for all patients including those with functional abnormalities. A stenosis was found 9 times with the Doppler and 10 times by angiography, there being disagreement between the two techniques in one case. The location of the stenosis was the same in the 9 concordant cases. There was a very strong correlation between the degree of stenosis found using the two techniques (p < 0.0001). In conclusion, measurement of recirculation appears to us to be of no interest for verifying a vascular access. On the other hand, the color Doppler seems to be an excellent choice for detecting an abnormality. An arteriographic confirmation seems necessary before correction.

Adolescent↗
PubMed1993

[Evaluation of neonatal prognosis using Doppler velocimeter in cases of a high risk fetus].

The authors describe the main characteristics of the Doppler method in the early diagnosis of chronic fetal distress, and report their personal results in the study of 51 high risk pregnancies. In their study the fetal doppler ultrasound findings were correlated with birth weight related to gestational age, and neonatal morbidity. The parameters established from the doppler ultrasound assessment were the placenta resistance (calculated from the formula of Pourcelot: R = S-D/S applied to the umbilical artery) and the cerebro-placental index, Rp/Rc, Rc being the index of cerebral arterial resistance. The diagnosis performance of the method appeared very good: the Rp index was found to be highly specific for hypotrophy (85,7%) and for neonatal morbidity (90%), the RCP index adding its own good sensitivity (85% for hypotrophy and 83,3% for neonatal morbidity). The authors conclude upon the interest to study simultaneously the fetal umbilical and cerebral arterial circulations. The pathological significance of the two indexes appears different so that they are to be complementary in the evaluation of fetal distress.

Female↗
PubMed1994

The hyperperfusion of the psoriatic plaque correlates histologically with dilatation of vessels.

We examined psoriatic lesions on the upper legs in 20 patients, using a two-dimensional Laser-Doppler-Scanner (Laser Doppler Perfusion Imager LDI, Lisca Development, Linköping/Sweden). The plaques were evaluated weekly during therapy with dithranol. Five plaques were reconstructed three-dimensionally before and after therapy (reconstruction program ANAT 3D, SIS, Münster, Germany). The psoriatic plaque was represented in the Laser Doppler Perfusion image as a sharply demarcated, hyperperfused area. The perfusion of the plaques dropped during therapy with dithranol to just slightly increased values, compared with normal skin (2.04 arbitrary units AU, healthy skin 1.1 AU). Using three-dimensional reconstruction, we investigated the volume of dermal vessels and the density of papillae. When compared, the volume of papillary vessels was twice as large in psoriatic as in healthy skin. The number of the papillae per square millimetre, detected by three-dimensional reconstruction, was not reduced significantly during therapy. We think that the increased perfusion of the psoriatic plaque is due to the combination of morphological (dilatation of vessels), dynamic (increased blood flow) and optical effects (reduced scattering and increased sampling depth of the laser-beam in acanthotic tissue).

Anthralin↗
PubMed1992

[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↗
PubMed1994

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↗
PubMed1982

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↗
PubMed1988

Partitional measurement of capillary and arteriovenous anastomotic blood flow in the human finger by laser-Doppler-flowmeter.

This study was made to see whether changes in blood flow through the capillaries and arteriovenous anastomoses (AVA's) of the human finger can be measured by noninvasive flowmetry. Total finger blood flow (FBF) was measured by venous occlusion plethysmography; blood flow was measured by a laser-Doppler flowmeter (ADVANCE, ALF-2100, Tokyo, Japan) using probes with optic fiber separations of 0.3 mm (LDF-0.3) and 0.7 mm (LDF-0.7). The maximum sensitivities for LDF-0.3 and LDF-0.7 were at depths of 0.8 and 1.2 mm from the tissue surface respectively. Two series of experiments were performed on separate days. In the first series the test hand was immersed in a water bath whose temperature (Tw) was 25 degrees C at an ambient temperature (Ta) of 25 degrees C. Tw was raised to 35 degrees C (local hand warming), which was then followed by an increase in Ta to 35 degrees C (whole body warming). FBF, LDF-0.3, and LDF-0.7 increased during these thermal stimulations. However, the relationship of FBF to LDF-0.3 showed two different regression lines. In contrast, the relationship of FBF to LDF-0.7 showed a single regression line. In the second series, with Ta at 35 degrees C, the test hand was immersed in a water bath at Tw 35 degrees C. Tw was then raised every 10 min by 2 degrees C steps from 35 to 41 degrees C. At Tw 39-41 degrees C, FBF and LDF-0.7 in the test hand were significantly decreased compared with those at Tw 35 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗