Search results for "Pulsatile flow"

Direct Numerical Simulation of Pulsatile Turbulent Channel Flow

2008

A combination of umbilical artery PI and normalized blood flow volume in the umbilical vein: Venous–arterial index for the prediction of fetal outcome

2008

Abstract Objective The objective was to assess the diagnostic power of the umbilical venous–arterial index (VAI) as a combination of the pulsatility index in the umbilical artery and the normalized blood flow volume in the umbilical vein for the prediction of poor fetal outcome. Study design This was a prospective clinical study in which the umbilical artery PI (UAPI), the normalized umbilical vein blood volume flow rate ( n UV; ml/min/kg estimated fetal body weight), the venous–arterial index (VAI; n UV/UAPI), and the pulsatility index (PI) in the umbilical artery (UA), uterine artery (utA), middle cerebral artery (MCA), and aorta were determined in 181 fetuses once (at between 17 and 41 w…

Relationship of choroidal thickness with pulsatile hemodynamics in essential hypertensive patients

2021

Controversy exists about the association of choroidal thickness (CTh) with blood pressure (BP) values. There is some evidence suggesting that central hemodynamics changes are associated with microvascular disease. Our study was aimed to assess the relationships between CTh and clinic and 24-h BP and between CTh and estimated 24-h aortic pulse pressure (aPP), 24-h aortic systolic BP (aSBP), and 24-h aortic augmentation index (aAIx) in a group of hypertensive patients. We enrolled 158 hypertensive subjects (mean age 48 ± 13 years) all of which underwent evaluation of the choroidal district by Swept-Source optical coherence tomography (SS-OCT) and 24-h BP monitoring, in order to measure periph…

Pulsatile and steady 24-h blood pressure components as determinants of left ventricular mass in young and middle-aged essential hypertensives

2003

In order to explore the relations between left ventricularmass (LVM) and the pulsatile (pulse pressure) andsteady (mean pressure) components of the bloodpressure (BP) curve, 304 young and middle-agedessential hypertensive patients were studied by meansof 24-h ambulatory BP monitoring and echocardio-graphy. In the overall study population, both the BPcomponents showed significant correlations with LVM.These correlations were unevenly distributed in thesubgroups of subjects younger and in those older than50 years. While in this latter subgroup, in multivariateanalysis, both 24-h mean BP (24-MBP) (b¼0.27;P¼0.008) and 24-h pulse pressure (24-h PP) (b¼0.23;P¼0.02) were associated with LVM, in th…

The Renal Dangers of an Increased Cardio-Ankle Vascular Index

2020

Although a number of longitudinal investigations assessed the ability of aortic PWV to predict the development of kidney disfunction or progression of renal disease, little is known about the association of CAVI with the risk of renal function deterioration. In the current issue of the American Journal of Hypertension is published a paper of Itano S et al, that add a new piece of evidence in this scenario. The authors analyzed data from the national health check-up system in Japan, including 24.297 participants with normal baseline kidney function. They found that those with CAVI measurements ≥8.1 had a higher risk for CKD events compared to their counterparts with CAVI measurements <8.1…

Quantitative myocardial perfusion magnetic resonance imaging: the impact of pulsatile flow on contrast agent bolus dispersion.

2011

Myocardial blood flow (MBF) can be quantified using T1-weighted first-pass magnetic resonance imaging (MRI) in combination with a tracer-kinetic model, like MMID4. This procedure requires the knowledge of an arterial input function which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest. The aim of this study was to investigate the dispersion under conditions of physiological pulsatile blood flow, and to simulate its effect on MBF quantification. The dispersion was simulated in coronary arteries using a computational fluid dynamics (CFD) approach. Simulations were accomplished on straight vessels wit…

Which is the best ultrasound parameter for the prediction of adverse perinatal outcome within 1 day of delivery?

2021

To compare the accuracies of several sonographic parameters for the prediction of adverse perinatal outcome (APO) prior to delivery.This was a prospective study of fetuses attending the day hospital unit of a tertiary referral hospital that were scanned at 34-41 weeks and gave birth within 24 h of examination. APO was defined as a composite of abnormal intrapartum fetal heart rate or intrapartum fetal scalp pH7.20 requiring urgent cesarean section, neonatal umbilical cord pH7.10, 5' Apgar score7 and postpartum admission to neonatal or pediatric intensive care units. The accuracies of the middle cerebral, vertebral and umbilical arteries pulsatility index multiples of the median (MoM), the c…

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…

Dilation of the ductus venosus by stent implantation increases placental blood perfusion in fetal sheep.

2006

The reduction of resistance to flow in the ductus venous (DV) and a decrease of blood supply to the liver serve for the survival of the fetus during hypoxia. The present study investigated the influence of the increased diameter of the DV on placental blood perfusion.In 15 ewes with twin pregnancies at gestational ages of 117 +/- 4 days, a stent (4 or 5 mm) was placed into the DV of 1 twin (DV(stent) group) under ultrasound guidance. Blood flow rates in the umbilical vein (UV) and DV of both fetuses were measured using Doppler ultrasound. Eight pairs of twin fetuses were included for the final analysis.The dilatation of the DV increased the blood flow volume rate passed through the DV from …