Search results for "doppler"
showing 10 items of 637 documents
Cardiomyopathic lentiginosis: an echo-Doppler report
1995
We report a case of a 64-year-old woman with cardiomyopathic lentiginosis. All the echocardiographic features of a hypertrophic obstructive cardiomyopathy were detected, with an accurate noninvasive measure of the left ventricle outflow gradient.
Experimental signature of optical wave thermalization through supercontinuum generation in photonic crystal fiber
2009
International audience; We report an experimental, numerical and theoretical study of the incoherent regime of supercontinuum generation in a two zero dispersion wavelengths fiber. By using a simple experimental setup, we show that the phenomenon of spectral broadening inherent to supercontinuum generation can be described as a thermalization process, which is characterized by an irreversible evolution of the optical field towards a thermal equilibrium state. In particular, the thermodynamic equilibrium spectrum predicted by the kinetic wave theory is characterized by a double peak structure, which has been found in quantitative agreement with the numerical simulations without adjustable pa…
Numerical and experimental study of liquid metal stirring by rotating permanent magnets
2018
In this work, we study liquid gallium stirring by rotating permanent magnets. We demonstrate possibility of easily creating different flow patterns by rotating permanent magnets, which can be industrially important for controlling heat and mass transfer processes in the system. Unlike the typical approach of simulating magnet rotation as a transient problem and time-averaging the Lorentz forces, we solve the magnet rotation as a harmonic (frequency domain) problem, which leads to forces equal to time-averaged ones and decreases the simulation time considerably. Numerical results are validated using qualitative flow structure results from the neutron radiography visualization of tracer parti…
Hemodynamic changes in splanchnic circulation after orthotopic liver transplantation in patients with liver cirrhosis
2002
Background: Liver cirrhosis increases portal vein pressure and alters the splanchnic circulation. With Doppler sonography, we investigated the hemodynamic changes in the portal vein, superior mesenteric artery, hepatic and splenic arteries and spleen size in a group of patients with end-stage liver disease before and after orthotopic liver transplantation (OLT). Methods: Ten patients (seven male, three female; mean age = 48.8 ± 7.6 years) who underwent OLT for liver cirrhosis mainly associated with hepatitis C virus infection completed the study. The control group consisted of 10 patients matched by sex and age who had no gastroenterologic or vascular diseases. All patients underwent duplex…
Color Doppler Ultrasound in Portal Hypertension
2020
Portal hypertension is one of the most important causes of morbidity and mortality in cirrhotic patients. A color Doppler evaluation of the left gastric vein (LGV) has proven utility in the prediction of esophageal varices and variceal bleeding in patients with portal hypertension. The purpose of this review is to discuss the ultrasound evaluation, imaging findings, and clinical application of Doppler ultrasound in the assessment of the LGV. Knowledge of the color Doppler technique and imaging findings of the LGV may help clinicians improve the monitoring of portal hypertension and predict patients with a high risk of esophageal varices.
Cardiac involvement in patients with cirrhosis: a focus on clinical features and diagnosis
2016
Cirrhotic heart has been traditionally considered protected from cardiovascular disease, even if a large amount of literature has recently shown that patients affected by chronic liver disease are exposed to cardiovascular events, as well. Since the first recognition of cardiac involvement in cirrhosis, all published studies explain that decompensated cirrhotic patients suffer from haemodynamic changes, currently known as hyperdynamic syndrome, which finally lead to cirrhotic cardiomyopathy. This is defined by the presence of a subclinical systolic dysfunction unmasked under stress conditions, impaired diastolic function and electrophysiological abnormalities, in the absence of any known ca…
ADV measurements of velocity distributions in a gravel-bed flume
2003
Velocity measurements carried out by an acoustic doppler velocimeter (ADV) in a rectangular laboratory flume having a gravel bed are presented. The velocity profiles are measured in six verticals of the channel cross-section having an increasing distance (from 4 to 38.5 cm) from the flume wall. The experimental runs are carried out for five different bed arrangements, characterized by different concentrations of coarser elements, and for the two conditions of small- and large-scale roughness. For both hydraulic conditions, the velocity measurements are first used to test the applicability of the Dean profile and of the logarithmic profile corrected by a divergence function proposed in this …
PROTOCOLLO ECOGRAFICO DEL PAZIENTE CON SCOMPENSO CARDIACO: RISULTATI AGGIORNATI DELLO STUDIO MULTICENTRICO SIUMB ABCDE 2018-2022
2019
Lo scompenso cardiaco è una sindrome clinica caratterizzata da specifici segni e sintomi causati da anomalie cardiache di tipo strutturale e/o funzionale. La prevalenza dello scompenso cardiaco è di circa 1-2% nella popolazione adulta dei paesi industrializzati, aumenta fin oltre il 10% oltre i 70 anni ed è la maggiore causa di ospedalizzazione oltre che di disabilità. L’approccio ecografico al paziente con scompenso cardiaco è ad oggi pratica comune, sia per la valutazione della funzionalità cardiaca, sia per il monitoraggio dello stato di volemia che per la quantificazione del liquido interstiziale. Dal 2018 è in corso uno studio multicentrico italiano (“ABCDE”) patrocinato dalla SIUMB ch…
Influence of PEEP on cerebral blood flow and cerebrovascular autoregulation in patients with acute respiratory distress syndrome.
2013
High levels of positive end-expiratory pressure (PEEP), as part of the treatment in patients with acute respiratory distress syndrome (ARDS), may prevent alveolar collapse and maintain oxygenation. PEEP potentially reduces cerebral venous return, increases intracranial blood volume, and may, therefore, affect cerebral blood flow (CBF) and cerebrovascular autoregulation (AR). This study investigates the effect of PEEP on CBF and AR in patients with respiratory failure.CBF velocity was measured using transcranial doppler and correlated with the invasive arterial blood pressure curve to calculate the index of AR Mx (Mx0.3 indicates impaired AR). Mx was measured at lower PEEP levels and after i…
Therapeutic Application of 20-kHz Transcranial Ultrasound in an Embolic Middle Cerebral Artery Occlusion Model in Rats
2007
Background and Purpose— Therapeutic application of diagnostic ultrasound has been shown to improve recanalization rates in patients with acute cerebral vessel occlusion. There is experimental evidence that low-frequency ultrasound may be superior. This study was designed to evaluate the therapeutic efficacy and safety of low-frequency ultrasound in an embolic middle cerebral artery occlusion model in rats. A parameter setting was used that had not previously shown any side effects and interactions with healthy rat brain tissue. Methods— Male Wistar rats were submitted to middle cerebral artery clot embolism and transcranial treatment with 20-kHz continuous-wave ultrasound (0.2 W/cm 2 ), ei…