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PubMedDate not supplied

[The value of ultrasonic flow measurement in the postoperative surveillance and observation of arteriovenous fistulae for chronic haemodialysis (author's transl)].

Measurement of instantaneous circulatory rates by Doppler effect per-operatively, at the 6th hour, the 8th day and the 2nd month was used to observe haemodynamic changes in 20 arteriovenous fistulae created for the purpose of chronic haemodialysis. Blood flow rates, initially low, increased up to the 8th day and were subsequently stable. A circulatory rate of 22 cm/s in the drainage vein 6 hours after the operation would seem to guarantee the permeability of the therapeutic arteriovenous anastomosis. To some extent, the authors have described the course of therapeutic arteriovenous fistulae during the first two months. Criteria of permeability have been determined making it possible to spare the vascular capital of these patients.

Arteriovenous Shunt, Surgical↗
PubMed1975

[Use of the Doppler signal in the determination of fetal cardiac rhythm].

The authors, after going over in brief the technical details of the physical characteristics of ultra-sounds and in particular the Doppler effect, describe a new cardiotachymeter using ultra-sounds which they have developed at the Baudelocque Maternity Hospital in Paris. In the first month in which they used this apparatus they kept 37 records on women who had not yet started labour and 36 records on women who were in labour. In 9 of the latter group they recored the fetal cardiac rhythm by the external route using ultra-sound pick-up and a recording by internal route using the fetal electrocardiogram. Tracings were comparable. It is interesting to note that even when uterine contractions are very strong indeed or the mother moves a lot the ultra-sound pick-up very rarely loses the fetal signal.

Adult↗
PubMed1981

[Reliability and value of arterial blood-flow monitoring during operation (author's transl)].

The predictive values of blood-flow monitoring using the Doppler effect during operation, to detect anatomical causes of correctable low blood flow or early thrombosis in the absence of correction, was studied in 309 cases of revascularization. When employed under precise conditions, this technique was found to be of high predictive value. Flow rates can be classified in four risk zones: very high, high, low, or nil. In practice, whenever values fall below a critical threshold of 130 ml/min at the iliofemoral level or 55 ml/min at the femoropopliteal level, arteriography should be conducted to establish the cause of the reduced flow, and to enable immediate correction of any technical fault, or improvement in distal flow. The value of this method is shown by the fact that of 44 cases with reduced flow, 22 could not be improved, and early thrombosis occurred in 70% while, in 20 cases, improvement was obtained, and early thrombosis occurred in only 10%. The use of blood-flow monitoring techniques during operation can be assumed to have reduced the incidence of early thrombosis by 27% in those cases with diminished flow, and by 4% in the overall group.

Arteries↗
PubMed1983

Measurement of microvascular blood flow in cancellous bone using laser Doppler flowmetry and 133Xe-clearance.

Blood flow in cancellous bone with varying vascular density was investigated simultaneously with Laser Doppler Flowmetry (LDF) and 133Xe-clearance. The cancellous bone subapical to 2 contralateral incisors in the mandibles of 17 young pigs was used as an experimental model. Light from a 2 mW He-Ne-laser was guided through an optical fibre to a flowmeter probe. Stainless steel probe-holders firmly inserted in the pulpal canals of the two incisors served as the probe entrance to cancellous bone for blood flow recording. Due to the Doppler effect, the light scattered by circulating blood cells undergoes a frequency shift. The back-scattered light picked up by optical fibres in the probe, was guided to a photosensitive device, where it was demodulated. After signal processing, a signal referred to as the Blood Flow Value (BFV) was recorded on a pen recorder. Rhythmical variations (vasomotion) in BFV with frequencies from 2-11 cycles/min were observed in 6% of recordings made initially after probe-holder implantation, and in 34% of the recordings made 5 weeks later. On this occasion, a marked increase in BFV was recorded. Histological examination showed increased vascularity in the bone tissue. The reproducibility error of LDF was 7.4% and temporal changes in BFV, apart from vasomotion, were 8.3%, provided no injections or manipulations of the probe were made. Spatial variations in BFV were found to be related to the vascular density. 2 successive recordings by LDF from the same bone area were highly correlated (r = 0.98). The corresponding figure for 2 logarithmic decay rates of locally injected 133Xe was 0.76. No correlation between BFV and 133Xe-clearance could be demonstrated.

Animals↗
PubMed1996

The Doppler illusion: the influence of dynamic intensity change on perceived pitch.

Four studies illustrate a new auditory illusion associated with the Doppler effect and demonstrate a new influence of dynamic intensity change on perceived pitch. Experiment 1 confirmed the existence of a popular belief that the pitch of a moving sound source rises as the source approaches. Because there is no corresponding rise in frequency, the authors refer to the perceived pitch rise as the Doppler illusion. Experiment 2 confirmed that the effect occurs perceptually, so the belief in a "naive principle" of physics has a perceptual basis. Experiment 3 confirmed the effect does not occur under matched static conditions. Experiment 4 showed that the influence of dynamic intensity change on perceived pitch occurs outside the realm of Doppler stimuli. The findings support a dynamic dimensional interaction of pitch and loudness, with marked differences in the perception of pitch and loudness under static and dynamic conditions.

Adult↗
PubMed2006

Virtual histology and color flow intravascular ultrasound in peripheral interventions.

The quality and interpretation of intravascular ultrasound (IVUS) imaging has been revolutionized in recent years by two new and major advances: virtual histology and color flow IVUS. Virtual histology intravascular ultrasound (VHIVUS) is a catheter-based technology where IVUS is generated from the transducer on the catheter tip and the reflected signals from the artery wall produce a color-coded map of the arterial disease. Different histological constituents of the plaque produce different reflected signals and these are assigned different colors (dark green, fibrous; yellow/green, fibrofatty; white, calcified; red, necrotic lipid core plaque). This color-coded map assists the interventionalist in understanding more fully how the lesion will behave at the moment of treatment, whether it will resist complete stent deployment or be liable to embolization. Originally introduced for coronary interventions, VHIVUS is now being applied to peripheral situations. Because it provides a detailed and close-proximity view of plaque, its potential to improve the safety and efficacy of carotid endoluminal repair is stimulating substantial interest. Similarly, color flow IVUS provides greater understanding for the operator of blood flow, and the interface between the vessel wall and the blood stream, lumen size, and success of treatment. Color flow IVUS does not use the Doppler effect, but creates real-time images that resemble color flow Doppler ultrasound. These two technological advances in IVUS have greatly improved the ability of the endovascular specialist to understand the arterial disease they are treating and to assess the completion of treatment.

Blood Vessel Prosthesis Implantation↗
PubMed1992

Influence of the Coanda effect on color Doppler jet area and color encoding. In vitro studies using color Doppler flow mapping.

We studied surface adherence and its effects on color Doppler jet areas and color encoding in an in vitro model with a noncompliant receiving chamber into which a steady flow jet was directed parallel to either a straight or a curved surface adjacent to and 4 mm away from the inflow orifice (1.50 mm2) with the control condition being a free jet matched for flow rates and driving pressures. Jets were imaged perpendicular to the plane of the surface, the plane in which most clinical images of jet-surface interactions are obtained. Ten different flow rates ranging from 0.13 to 0.30 l/min were used. Surface-adherent jet areas were smaller than control jets for every driving pressure-volume combination (paired t test, p less than 0.01). Computer analysis of color Doppler images showed more green and blue (reverse flow) pixels on the surface side of the adherent jets than the control jets (p less than 0.05), suggesting that viscous energy loss and flow deceleration and reversal play a role in the jet-surface interaction. Analysis of variance demonstrated that linear regression slopes of flow rate versus jet area for surface jets were lower (slopes, 11-21 cm2/l/min; r = 0.95-0.97) than those for the control (slope, 33 cm2/l/min; r = 0.97) (p less than 0.0001). Surface adherence (Coanda effect) influences jet size and color encoding, causing smaller color Doppler jet areas and greater variance and reverse velocity encoding.

Coronary Circulation↗
PubMed1990

Blood flow: insights from ultrasound.

Ultrasonic pulse-echo systems can provide range-finding, time-position and real-time two-dimensional images of soft-tissue structures within the body. The Doppler effect can be used to study motion and blood flow. Continuous wave Doppler instruments provide information about velocity and direction of flow; depth discrimination can be obtained by pulsing the ultrasound. Two-dimensional Doppler flow imaging can be achieved by manual scanning of a probe over the skin surface. The combination of real-time pulse-echo imaging with pulsed Doppler blood flow detection in the duplex scanner makes it possible to localize the anatomical position of the Doppler sample volume. Real-time Doppler colour flow imaging combines traditional ultrasonic scanning with a two-dimensional flow map. Using appropriate ultrasonic instruments, blood flow volume rates, blood flow velocity profiles, pressure gradients, orifice areas, flow disturbances, jets, characteristics of blood vessels and the circulatory system, and tissue perfusion can all be investigated. These investigations have clinical applications in the study of cardiac, cerebral and peripheral blood flow, blood flow in the female pelvis, the fetus, the abdomen, the neonate, and in malignant tumours. Contemporary ultrasonic diagnosis employs exposure levels that are apparently free from biological risk, but other factors need to be taken into account in considering the prudent use of ultrasonic methods. Promising research is being carried out into the mechanism of ultrasonic scattering by blood, Doppler speckle, time-domain processing for blood flow imaging, methods for increasing the scanning speed, Doppler flow microscopy and contrast agents. The new technology that will result from this research should lead to further substantial progress in ultrasonic blood flow studies.

Blood Circulation↗
PubMedDate not supplied

[Role of Doppler velocimetry in diagnosis of TMJ dysfunction. 2. Clinical evaluation].

In order to evaluate the efficacy of Doppler effect in the diagnosis of dysfunctional TMJ sounds, we have analysed ten Doppler tracings of normal subjects, ten of subjects with reciprocal clicking and ten with locking (complete anterior dislocation of the disc). The results show that to every dysfunctional pathology corresponds a precise type of tracing whose acknowledgment is immediate.

Humans↗
PubMed1993

Cellular effects of diagnostic Doppler ultrasound on murine spermatogenic cells monitored by flow cytometry.

A study has been carried out to investigate the possible effects caused by Doppler diagnostic ultrasound on murine spermatogenesis. The frequency of the different types of cells has been analyzed using flow cytometry. Exposure to ultrasound was carried out using a commercial device used in diagnostic conditions. Male hybrid mice were exposed to ultrasound for 30 min and observed from 7 to 35 days after treatment. Flow cytometrical analysis showed changes in the relative frequency of the elongated spermatids and this was used as an end-point. A statistically significant decrease in the frequency of this cell type was observed after 7 and 35 days with both pulsed and continuous ultrasound. With the former, a decrease was also seen in this compartment after 14 and 21 days. Our results have shown that diagnostic ultrasound used in the Doppler technique induces effects on specific cell types of murine spermatogenesis.

Animals↗
PubMed1993

Comparison of conventional and transverse Doppler sonograms.

When measuring flow velocity using the conventional ultrasonic Doppler effect, beam axis-to-flow angles approaching 90 degrees are avoided as the Doppler spectrum frequency shift is known to go to zero at this angle. In this paper, the conventional Doppler technique is compared with the transverse Doppler method, in which the Doppler spectrum bandwidth is used to estimate flow, allowing flow to be probed at 90 degrees. The comparison is made using a moving thread flow phantom capable of executing various velocity profiles. This technique may allow the probing of vessels that are inaccessible to conventional oblique probing, thus complementing the conventional Doppler technique.

Blood Flow Velocity↗
PubMed1989

[Quantitative measure of the output of the deep abdominal vessels with a new device Duplex. Preliminary results].

Deep abdominal vessels blood flow can be measured noninvasively with the relation Q = V x A, where Q = flow, V = blood velocity and A = area of the considered vessel. In most Duplex devices, V is only calculated as a mean by the Doppler effect and A estimated by an echograph. Our newly developed multi-gated pulsed Doppler provides the velocity profile across the vessel, so minimizing errors in flow determination. On fifty healthy volunteers, we found flow of 717 +/- 238 ml/min for the portal vein, 1594 +/- 293 ml/min for the upper abdominal aorta and 794 +/- 168 ml/min for the lower aorta. These results are obtained through many technical and practical problems, but are feasible, even if still subject to errors. Further investigation will determine if the technique is also suitable for patients. Better assessment of deep abdominal vessels hemodynamics may be expected.

Adult↗
PubMedDate not supplied

Prostaglandin E1 infusion for small vessel arterial ischaemia.

The effects on severe arterial ischaemia of infusions of Prostaglandin E1 (PGE1) a vasodilator and inhibitor of platelet aggregation, were studied in 49 patients (aged 17-80). Criteria for patient selection included rest pain and/or digital ulceration and gangrene secondary to predominantly small vessel disease. PGE1 was infused at a low (6 ng/kg/min), intermediate (10 ng/kg/min) or high (14 ng/kg/min) dose rate via a central venous cannula on 52 occasions without serious side effects. Doppler studies, pulse volume recordings and infra red radiometry were used to quantify the clinical effects. Improvements in digital perfusion were demonstrated by increased pulse volume amplitude (7.1 +/- 1.1 to 21.6 +/- 2.7 mm mean +/- SEM) which remained significantly raised at 6 weeks (14.2 +/- 2.9 mm; P = less than 0.001 paired t test). Infra red digital temperatures were also significantly raised 6 weeks post infusion (27.2 +/- 0.6 degrees C to 29.5 +/- 0.6 degrees C; P less than 0.001). The majority of patients reported improvement in pain, and two thirds of 12 superficial ulcers healed in 6 weeks. These results show that PGE1, improves digital perfusion for several weeks in patients with severe arterial ischaemia.

Adolescent↗
PubMed1982

[Static gamma phlebography with Tc 99-marked blood erythrocytes].

Our personal modification of the isotopic gammaphlebography technique involving red blood cells marked with (a 10 mCu dose of) Tc 99 is described. This process involves a further intravenous injection of the isotope, after a previous injection of 2 ml Cl2Sn, which allows re-injection of the radioactive bolus after its passage through the lung region, so that more accurate and complete images are obtained, without performing any other invasive examinations of the lower extremities. 80 patients are studied, and their study is completed by means of the Doppler effect and impedance rheopltethismography. The results are discussed: 87,5% and 88,6% of good correlations in Doppler are obtained for acute and chronic cases respectively. 77,75% and 92% with impedance rheoplethismography in the same cases. Six evidencing cases are shown.

Adult↗
PubMedDate not supplied

[Static scintigraphy using technetium 99 labelled red blood cells].

Our personal modification to the isotopic gammaphlebography technique involving red blood cells marked with (a 10 mCu dose of) Tc-99 is shown. This process involves further the injection of the isotope endovenously in the inner face of the elbow articulation, after having first injected 2 ml Cl2Sn, which allows re-injection of the radioactive bolus after its passage through the lung region, so that more accurate and complete images may be obtained, without having to perform any manipulations in the lower extremities. 80 patients are studied, and their study is completed by means of the Doppler Effect and impedance rheopletismography. The results are shown : 87,5% and 88,5% of good correlations in Doppler are obtained for acute and chronic cases respectively. 77,75% and 92% with impedance rheopletismography in the same cases. Six evidencing cases are shown.

Adult↗
PubMed1988

[Compared validity of the criteria of quantification of aortic insufficiency using pulsed and continuous Doppler].

In order to evaluate the severity of aortic valve regurgitation (AVR) by means of simple criteria, we compared the feasibility and reliability of two methods: (1) pulsed doppler ultrasound suprasternal recording in the aortic sinus area, with calculation of the regurgitation fraction by planimetry of the systolic and diastolic curves, and with measurement of end-diastolic velocity, or end-diastolic doppler effect (EDDE); this was done in 114 subjects (84 patients with AVR and 30 controls); (2) continuous wave doppler ultrasound apical recording of the left intraventricular jet, with measurement of the velocity decrease slope (S) and of the velocity half-decrease time (T 1/2); this was done in 46 patients with AVR. Doppler results were compared with Seller's angiographic classification of AVR in 4 grades. Planimetry could be performed in only 41% of patients in this series. This measurement seems to be feasible only when perfect recording of an increased systolic flow (peak velocity higher than 1.2 m/s) can be performed, which is usually limited to cases with major regurgitation. EDDE was easier to record (84/84 patients). When above 5 cm/s it is a good reflection of AVR severity, and when above 20 cm/s it indicates a major AVR (3/4 or 4/4 at angiography), with an 81% sensitivity and a 91% specificity. Continuous wave doppler ultrasound apical recording could be used in 80% of the cases (37/46 patients). With this method, a more than 3 m/s slope is a highly specific (8/8) but not very sensitive (8/13) sign of major AVR. A T 1/2 value lower than 650 ms is a specific (12/12) and sensitive (12/13) sign of severe AVR.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1993

Color Doppler imaging of orbital arteries for detection of carotid occlusive disease.

BACKGROUND AND PURPOSE: Distal to a hemodynamically significant stenosis, the Doppler effect becomes dampened. Thus, measuring the flow profile in the ophthalmic artery and the central retinal artery with color Doppler imaging may provide hemodynamic information about the carotid circulation. METHODS: To validate the flow profile measurement with color Doppler imaging in the ophthalmic and central retinal arteries and to determine the sensitivity and specificity of this examination in the detection of hemodynamically significant carotid stenosis, we compared color Doppler imaging examinations with ocular pneumoplethysmography and ophthalmodynamometry examinations in 66 patients with atherothrombotic ischemic cerebrovascular disease. The degree of carotid stenosis in these patients was determined by a duplex scan with color Doppler imaging, and 57 patients underwent angiography to verify the stenosis. RESULTS: The flow velocities (systolic peak velocity and end-diastolic velocity) and pulsatility indices (A/B ratio and resistance index) in the ophthalmic and central retinal arteries decreased as the degree of carotid stenosis increased. There is a statistically significant difference in the mean of systolic peak velocity and the mean of end-diastolic velocity of the ophthalmic and central retinal arteries among groups with various degrees of carotid stenosis (P < .02). Using the flow velocities of the ophthalmic and central retinal arteries to diagnose carotid stenosis (> or = 75% stenosis and occlusion), 8 cm/s for systolic peak velocity in the central retinal artery and 29 cm/s for systolic peak velocity plus flow direction reversal in the ophthalmic artery gave the maximum accuracy (sensitivities, 84% and 85.7% and specificities, 89.6% and 81.7%, respectively). The systolic peak velocity in the central retinal artery varied directly with the systolic pressure of the ophthalmic and central retinal arteries. CONCLUSIONS: The flow velocity and pulsatility in orbital arteries examined by color Doppler imaging provide further hemodynamic information; this test can be used to complement current sonographic examination of carotid disease.

Aged↗