Search results for "HEMODYNAMICS"
showing 10 items of 511 documents
Reliability of Hemodynamic Parameters Measured by a Novel Photoplethysmography Device
2011
Three channel photoplethysmography (PPG) signal pulse wave studies of the leg’s conduit arteries during rest conditions were performed. The obtained data of each channel showed similar values, proving arterial PPG as a reliable and repeatable method to assess arterial waveform parameters. A validation experiment was carried out by acquiring signals from three identical IR PPG sensors, which were placed on different sites over the leg’s conduit arteries during rest conditions. Coefficients of variation (CV) were calculated at a 95% confidence interval by comparing results of each subject during multiple attempts. This data processing leads us to certain criteria of improvements in our method…
Regional variation of wall shear stress in ascending thoracic aortic aneurysms.
2014
The development of an ascending thoracic aortic aneurysm is likely caused by excessive hemodynamic loads exerted on the aneurysmal wall. Computational fluid-dynamic analyses were performed on patient-specific ascending thoracic aortic aneurysms obtained from patients with either bicuspid aortic valve or tricuspid aortic valve to evaluate hemodynamic and wall shear parameters, imparting aneurysm enlargement. Results showed an accelerated flow along the outer aortic wall with helical flow in the aneurysm center for bicuspid aortic valve ascending thoracic aortic aneurysms. In a different way, tricuspid aortic valve ascending thoracic aortic aneurysms exhibited normal systolic flow without su…
Intraluminal Doppler-Sonography: Analysis and “in Vitro Test” of a New Device
1992
In treating patients with coronary heart disease it’ s necessary first to determine what influence the stenose has on the coronary blood flow. This is a prerequisite for any invasive treatment method. Coronary angiography explosures are only partially useful in attaining a functional evaluation of the haemodynamic stenoses.
Anti-Hypotensive Treatment and Endothelin Blockade Synergistically Antagonize Exercise Fatigue in Rats under Simulated High Altitude
2013
Rapid ascent to high altitude causes illness and fatigue, and there is a demand for effective acute treatments to alleviate such effects. We hypothesized that increased oxygen delivery to the tissue using a combination of a hypertensive agent and an endothelin receptor A antagonist drugs would limit exercise-induced fatigue at simulated high altitude. Our data showed that the combination of 0.1 mg/kg ambrisentan with either 20 mg/kg ephedrine or 10 mg/kg methylphenidate significantly improved exercise duration in rats at simulated altitude of 4,267 m, whereas the individual compounds did not. In normoxic, anesthetized rats, ephedrine alone and in combination with ambrisentan increased heart…
Relative incidence and mortality of congenital heart defects diagnosed by angiohemodynamic methods: a 17-year study.
1992
Over a 17-year period (January 1971 to January 1988), 2322 children, aged 0-14 years, were diagnosed as having congenital heart disease (CHD) by cardiac catheterization and angiography. Excluding those with highly complex or undiagnosed defects, there were 2156 children with CHD, 72.4% of whom were treated surgically, with a total surgical mortality rate of 24.1%. After a mean follow-up of 9 years the overall mortality of the cohort was 29.9%, 29.1% occurring in the first month of life, 39.6% between 1 month and 1 year, and 31.2% between 1 and 14 years. The incidence, mortality, and age at death of each cardiac defect are presented and compared with the results of other studies. The overall…
Role of computational modeling in thoracic aortic pathology: A review
2014
Thoracic aortic diseases are life-threatening conditions causing significant mortality and morbidity despite advances in diagnostic and surgical treatments. Computational methods combined with imaging techniques provide quantitative information of disease progression, which may improve clinical treatments and therapeutic strategies for clinical practice. Since hemodynamic and wall mechanics play important roles in the natural history and progression of aortic diseases, we reviewed the potential application of computational modeling of the thoracic aorta. We placed emphasis on the clinical relevance of these techniques for the assessment of aortic dissection, thoracic aortic aneurysm, and ao…
Management of high-risk pulmonary embolism in an "unstable medical environment": Not only a matter of hemodynamic.
2020
On the existence of weak solution to the coupled fluid-structure interaction problem for non-Newtonian shear-dependent fluid
2016
We study the existence of weak solution for unsteady fluid-structure interaction problem for shear-thickening flow. The time dependent domain has at one part a flexible elastic wall. The evolution of fluid domain is governed by the generalized string equation with action of the fluid forces. The power-law viscosity model is applied to describe shear-dependent non-Newtonian fluids.
Effects of Nifedipine on Blood Pressure, Arterial Compliance and Left Ventricular Mass in Elderly Patients with Isolated Systolic Hypertension
1989
The aim of this study was to evaluate the effects of acute and chronic administration of slow-release nifedipine (SRN) on blood pressure (BP), aortic index (AI), average wall stress (AWS), left ventricular mass (LVM), and other hemodynamic parameters in elderly patients with isolated systolic hypertension (ISH) (systolic blood pressure [SBP] > 175 mmHg). We studied 10 patients (mean age 73.7 ± 5.6 years) in which after a washout period, in basal conditions, 3 h after the administration of SRN (20 mg), and 180 days after chronic therapy (40 mg daily), we evaluated the changes of BP, HR, AI, AWS, LVM, and other parameters obtained by means of echocardiography. After SRN we observed a signific…