Search results for "Hemodynamics"
showing 10 items of 511 documents
Transmission of arterial oxygen partial pressure oscillations to the cerebral microcirculation in a porcine model of acute lung injury caused by cycl…
2013
Cyclic recruitment and derecruitment (R/D) play a key role in the pathomechanism of acute lung injury (ALI) leading to respiration-dependent oscillations of arterial partial pressure of oxygen (Pa(O(2))). These Pa(O(2)) oscillations could also be forwarded to the cerebral microcirculation.In 12 pigs, partial pressure of oxygen was measured in the thoracic aorta (Pa(O(2))) and subcortical cerebral tissue (Pbr(O(2))). Cerebral cortical haemoglobin oxygen saturation (Sbr(O(2))), cerebral blood flow (CBF), and peripheral haemoglobin saturation (Sp(O(2))) were assessed by spectroscopy and laser Doppler flowmetry. Measurements at different fractions of inspired oxygen (F(I(O(2)))) were performed …
Umbilical artery blood flow velocity waveforms during variable decelerations of the fetal heart rate
1991
Blood flow velocities of the umbilical arteries were measured by Doppler ultrasonography during variable decelerations of the fetal heart rate. The flow velocity waveforms, being normal between uterine contractions, showed either an unchanged flow velocity waveform with an exclusive fetal heart rate effect on end-diastolic velocities or a rapid change to absent and reverse diastolic flow during the decelerations, indicating an abrupt increase in placental resistance with a halt in placental perfusion. Computer-aided reconstruction of the fetal heart rate curve revealed the exact temporal relationship between the reduction of umbilical artery perfusion and deceleration of fetal heart rate. W…
Low-frequency ultrasound induces nonenzymatic thrombolysis in vitro.
2002
To evaluate whether ultrasound, applied over a distance of several centimeters and in the absence of thrombolytic agents, may have a thrombolytic effect on blood clots.Low-frequency (20 kHz) continuous wave ultrasound at different intensity levels (0.15-1.2 W/cm2) and exposure times (5, 10, and 20 minutes) was assessed for its potential to induce thrombolysis of fresh human blood clots. The ultrasound effect was also studied in combination with recombinant tissue-type plasminogen activator-mediated thrombolysis. Experiments were carried out in a flow model in degassed sodium phosphate buffer at 37 degrees C at a distance of 3 cm from the ultrasonic probe to the blood clots. Regardless of ul…
Systemic pulsatile pressure in type II endoleaks after stent grafting of experimental abdominal aortic aneurysms.
2003
Purpose: To investigate pressure and maximum rate of rise of systolic pressure (peak dP/dt) in completely excluded aneurysms and endoleaks to determine the hemodynamic impact of endoleaks. Methods: In mongrel dogs (n = 36) experimental aneurysms were created by insertion of a patch (portion of rectus abdominis muscle sheath) into the infrarenal aorta. In group I (n = 18), all aortic branches of the aneurysm were ligated and all aneurysms were completely excluded by stent grafts. Group II (n = 18) consisted of aneurysms with patent aortic side branches that represented sources of endoleaks. One week (n = 12), six weeks (n = 12), and six months (n = 12) after stent grafting, hemodynamic measu…
Normal Doppler Reference Values of the Pericallosal Artery
2015
Purpose: To provide the normal reference values of the Doppler flow of the pericallosal artery in relation to gestational age from 18 to 41 weeks of gestation. Materials and Methods: The pericallosal artery (PCA) was studied in 466 normal pregnancies. The pulsed Doppler evaluation of the pericallosal artery was done in A3 and A4 segments, and records from PI, RI and Vmax were studied. Results: The resistance index of the pericallosal artery in A3 / A4 segments exhibits a plateau from 18 to 31 weeks of gestation. After 31 weeks, a marked decrease becomes apparent. The pulsatility index of the pericallosal artery in A3 / A4 segments shows a plateau until 36 weeks of gestation. During the fina…
Effects of Methoxamine on Spontaneous Uterine Activity and Blood Flow of the Rat Uterus ‘in vivo’
1992
The vascular (blood pressure, heart rate and peripheral blood flow) and uterine (spontaneous motility) responses to intravenous methoxamine were studied in anaesthetized rats pre-treated with diethylstilboestrol. Methoxamine produced an increase (0.5-2 mg/kg) or did not modify (0.01 and 3 mg/kg) spontaneous uterine motility. The alpha 1-agonist also induced a hypertensive effect (0.1-3 mg/kg) accompanied by bradycardia at the highest doses, and a decrease in blood flow significantly greater in intestinal than uterine tissues. These effects were abolished by prazosin. The uterine action of methoxamine in vivo appears to result from the balance between myometrial alpha 1-excitatory effect and…
Defining right ventricular dysfunction by the use of echocardiography in normotensive patients with pulmonary embolism
2020
Although the prognostic value of various echocardiographic parameters of right ventricular dysfunction (RVD) was reported in normotensive patients with acute pulmonary embolism (PE), there is no generally accepted definition of RVD.The aim of the study was to compare echocardiographic parameters for the prediction of an adverse 30‑day outcome and create an optimal definition of RVD. Patients and methods: Echocardiographic parameters including the right ventricular to left ventricular diameter ratio (RV to LV ratio) and tricuspid annular plane systolic excursion (TAPSE) to predict PE‑related mortality, hemodynamic collapse, or rescue thrombolysis within th…
Past and present work practices of European interventional cardiologists in the context of radiation protection of the eye lens—results of the EURALO…
2018
International audience; This paper investigates over five decades of work practices in interventional cardiology, with an emphasis on radiation protection. The analysis is based on data from more than 400 cardiologists from various European countries recruited for a EURALOC study and collected in the period from 2014 to 2016. Information on the types of procedures performed and their annual mean number, fluoroscopy time, access site choice, x-ray units and radiation protection means used was collected using an occupational questionnaire. Based on the specific European data, changes in each parameter have been analysed over decades, while country-specific data analysis has allowed us to dete…
Renal resistive index: Beyond the hemodynamics
2020
We read with great interest the original article entitled “Prognostic significance of the renal resistive index in the primary prevention of type II diabetes” by Delsart et al1 In this issue of The Journal, the authors interestingly underlined the prognostic value of renal resistive index (RRI) in diabetic subjects and its role as an independent predictor of a first cardiovascular or renal event. Similar conclusions were previously obtained by others in different subsets of patients (hypertension, chronic kidney disease, or heart failure), in which intrarenal hemodynamic alterations showed to be independent predictors of cardiovascular events. It is likely that the mechanisms underlying ren…
Pulmonary Hypertension and Thromboembolic Disease
2008
Pulmonary hypertension (PH) is a disease group that includes a wide variety of entities leading to an increased pulmonary arterial pressure. This chapter describes the basic mechanisms that lead to PH and the possibilities of MRI in diagnosing different aspects. A MR imaging protocol is provided making MRI a comprehensive modality for the classification of the underlying disease and assessment of hemodynamics.