Search results for "hemodynamic"
showing 10 items of 526 documents
The "Renocentric Theory" of Renal Resistive Index: Is It Time for a Copernican Revolution?
2020
Ultrasound (US) with duplex Doppler scanning has spread to the capillary level, becoming an irreplaceable tool in daily clinical practice thanks to its characteristics: low cost, repeatability, and noninvasiveness. Moreover, US has become over time more sensitive and accurate; it can be considered an extension of the clinician’s hand. For this reason, it currently represents the ideal tool for first-level diagnostic use in several fields, and is the simplest and most flexible instrument for obtaining morphological and functional information on different organs, including the kidneys. In this issue of The Journal , Gigante, et al 1 propose to assess renal involvement in patients with systemi…
An Exploratory Look at Bicuspid Aortic Valve (Bav) Aortopathy: Focus on Molecular and Cellular Mechanisms
2019
Bicuspid aortic valve (BAV) is the most common congenital heart malformation. BAV patients are at increased risk for aortic valve disease (stenosis/regurgitation), infective endocarditis, thrombi formation and, in particular, aortic dilatation, aneurysm and dissection. This review aims at exploring the possible interplay among genetics, extracellular matrix remodeling, abnormal signaling pathways, oxidative stress and inflammation in contributing to BAV-associated aortopathy (BAV-A-A). Novel circulating biomarkers have been proposed as diagnostic tools able to improve risk stratification in BAV-A-A. However, to date, the precise molecular and cellular mechanisms that lead to BAV-A-A remain …
Hemodynamic Monitoring in Patients With Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis
2020
Aneurysmal subarachnoid hemorrhage (aSAH) often causes cardiopulmonary dysfunction. Therapeutic strategies can be guided by standard (invasive arterial/central venous pressure measurements, fluid balance assessment), and/or advanced (pulse index continuous cardiac output, pulse dye densitometry, pulmonary artery catheterization) hemodynamic monitoring. We conducted a systematic review and meta-analysis of the literature to determine whether standard compared with advanced hemodynamic monitoring can improve patient management and clinical outcomes after aSAH. A literature search was performed for articles published between January 1, 2000 and January 1, 2019. Studies involving aSAH patients …
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…