Search results for "Hemodynamic"

Evidence of unbalanced regulatory mechanism of heart rate and systolic pressure after acute myocardial infarction

2002

The interactions between systolic arterial pressure (SAP) and R-R interval (RR) fluctuations after acute myocardial infarction (AMI) were investigated by measures of synchronization separating the feedback from the feedforward control and capturing both linear and nonlinear contributions. The causal synchronization, evaluating the ability of RR to predict SAP (χs/t) or vice versa (χt/s), and the global synchronization (χ) were estimated at rest and after head-up tilt in 35 post-AMI patients, 20 young and 12 old. Significance and nonlinearity of the coupling were assessed by surrogate data analysis. Tilting increased the number of young subjects in which RR-SAP link was significant (from 17…

Chimney and periscope grafts to facilitate endovascular treatment of aortic transection in a patient with aberrant right subclavian artery

2014

Purpose: To report the use of parallel grafts to extend the proximal landing zone for stentgraft repair of aortic transection involving an aberrant right subclavian artery (ARSA). Case Report: A 28-year-old patient was referred for treatment of traumatic aortic transection with contained rupture at the level of an ARSA. Immediate thoracic endovascular aortic repair (TEVAR) was planned because of hemodynamic instability. To achieve rapid sealing and maintain perfusion to both subclavian arteries, a chimney stent to the left subclavian artery (LSA) and a periscope stent-graft to the ARSA were deployed successfully. After surgical repair of all fractures, the patient was discharged 1 month aft…

Impact of Thoracic Endografting on the Hemodynamics of the Native Aorta: Pre- and Postoperative Assessments of Wall Shear Stress and Vorticity Using …

2021

Purpose To quantify the hemodynamic consequences of thoracic endovascular aortic repair (TEVAR) by comparing the preoperative and postoperative wall shear stress (WSS) and vorticity profiles on computational fluid dynamics (CFD) simulations. Materials and Methods The pre- and postoperative computed tomography (CT) scans from 20 consecutive patients (median age 69 years, range 20–87) treated for different thoracic aortic pathologies (11 aneurysms, 5 false aneurysms, 3 penetrating ulcers, and 1 traumatic aortic rupture) were segmented to construct patient-specific CFD models using a meshless code. The simulations were run over the cardiac cycle, and the WSS and vorticity values measured at th…

Microalbuminuria fractional clearance and early renal permselectivity changes in essential hypertension.

1992

In order to verify if, in essential hypertension (EH), the microalbuminuria (AER) increase could be due to hemodynamic modifications or to glomerular structural changes, in 15 essential hypertensives (EHs) with 24-hour AER16 micrograms/min and in 15 EHs with 24-hour AERor = 16 micrograms/min, the day- and nighttime behavior of creatinine clearance (Ccr), as well as AER clearance (AER-C) and fractional clearance (AER-FC), and behavior of blood pressure (BP) was evaluated. Patients with 24-hour AER16 micrograms/min showed significantly higher values of 24-hour and daytime Ccr than the other group of EHs, while during the night period, there were no significant differences between the two grou…

2020

Motor control is associated with suppression of oscillatory activity in alpha (8–12 Hz) and beta (12–30 Hz) ranges and elevation of oxygenated hemoglobin levels in motor-cortical areas. Aging leads to changes in oscillatory and hemodynamic brain activity and impairments in motor control. However, the relationship between age-related changes in motor control and brain activity is not yet fully understood. Therefore, this study aimed to investigate age-related and task-complexity-related changes in grip force control and the underlying oscillatory and hemodynamic activity. Sixteen younger [age (mean ± SD) = 25.4 ± 1.9, 20–30 years] and 16 older (age = 56.7 ± 4.7, 50–70 years) healthy men were…

Application of C1-Esterase Inhibitor During Reperfusion of Ischemic Myocardium

2001

Background—Complement activation during reperfusion of ischemic myocardium augments myocardial injury, and complement inhibition with C1-esterase inhibitor (C1-INH) at the time of reperfusion exerts marked cardioprotective effects in experimental studies. Application of C1-INH in newborns, however, was recently reported to have dangerous and even lethal side effects. This study addresses the essential role of dosage in studies using C1-INH.Methods and Results—Cardioprotection by C1-INH was examined in a pig model with 60 minutes of coronary occlusion followed by 120 minutes of reperfusion. C1-INH was administered intravenously 5 to 10 minutes before coronary reperfusion without heparin at a…

Influence of dopexamine on hemodynamics, intramucosal pH, and regulators of the macrocirculation and microcirculation in patients undergoing abdomina…

2000

Abstract Objective: To investigate whether dopexamine hydrochloride beneficially influences splanchnic perfusion and regulators of the macrocirculation and microcirculation in patients undergoing surgery of the abdominal aorta. Design: Prospective, blinded, and randomized study. Setting: University-affiliated hospital. Participants: Twenty patients undergoing elective abdominal aortic surgery. Interventions: The patients were randomized to one of two groups. In the dopexamine group (DOP, n = 10), dopexamine, 1 μg/kg/min, was started before surgery and continued for 24 hours. In the control group (COG, n = 10), patients received saline solution as placebo. Extensive hemodynamic monitoring wa…

Aortic stiffness in patients with early sepsis

2014

Acute and chronic systemic inflammatory conditions are associated with aortic stiffening. Carotid-femoral pulse wave velocity (PWV), a marker of aortic stiffness, increases in patients with inflammatory diseases and independently correlates to levels of C-reactive protein (CRP). The effects of massive inflammatory response in early sepsis on mechanical properties of the aorta have not been investigated. The objective of the current study was to prospectively assess aortic stiffness in patients with early severe sepsis and septic shock and relate it to inflammatory and haemodynamic variables and outcome.

Computer Modeling for the Prediction of Thoracic Aortic Stent Graft Collapse

2011

OBJECTIVE: To assess the biomechanical implications of excessive stent protrusion into the aortic arch in relation to thoracic aortic stent graft (TASG) collapse by simulating the structural load and quantifying the fluid dynamics on the TASG wall protrusion extended into a model arch. METHODS: One-way coupled fluid-solid interaction analyses were performed to investigate the flow-induced hemodynamic and structural loads exerted on the proximal protrusion of the TASG and aortic wall reconstructed from a patient who underwent traumatic thoracic aortic injury repair. Mechanical properties of a Gore TAG thoracic endoprosthesis (W. L. Gore and Assoc, Flagstaff, Ariz) were assessed via experimen…

An In Vitro Phantom Study on the Role of the Bird-Beak Configuration in Endograft Infolding in the Aortic Arch.

2015

Purpose: To assess endograft infolding for excessive bird-beak configurations in the aortic arch in relation to hemodynamic variables by quantifying device displacement and rotation of oversized stent-grafts deployed in a phantom model. Methods: A patient-specific, compliant, phantom pulsatile flow model was reconstructed from a patient who presented with collapse of a Gore TAG thoracic endoprosthesis. Device infolding was measured under different flow and pressure conditions for 3 protrusion extensions (13, 19, and 24 mm) of the bird-beak configuration resulting from 2 TAG endografts with oversizing of 11% and 45%, respectively. Results: The bird-beak configuration with the greatest protr…