Search results for "Dynamics"

Quantitative contrast-enhanced myocardial perfusion magnetic resonance imaging: Simulation of bolus dispersion in constricted vessels

2009

Quantification of myocardial blood flow (MBF) by means of T 1 -weighted first-pass magnetic resonance imaging(MRI) requires knowledge of the arterial input function (AIF), 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, which leads to systematic underestimation of the MBF. The aim of this study was to simulate the dispersion along a simplified coronary artery with different stenoses. To analyze the dispersion in vessels with typical dimensions of coronary arteries, simulations were performed using the computational fluid dynamics approach. Simulations were accomplished on straight vessels wi…

Hemodynamic effects of dobutamine in children with cardiovascular failure.

1982

The effect of dobutamine, a synthetic catecholamine, was studied in 12 patients aged one day to 14 years with low cardiac output syndromes. After initial stabilization of the patients dobutamine was administered by continuous infusion in a dosage of 7.5 or 10 μg/kg/min. Heart rate, cardiac output (using thermodilution technique and/or pulse contour method), mean systemic and mean pulmonary artery pressures were determined before and after the dobutamine infusion. Systemic and pulmonary vascular resistances, cardiac index and stroke volume index were calculated. Cardiac output and cardiac index increased significantly in every patient, whereas the heart rate changed only slightly, suggesting…

Effect of chest compressions only during experimental basic life support on alveolar collapse and recruitment

2007

Summary Aim The importance of ventilatory support during cardiac arrest and basic life support is controversial. This experimental study used dynamic computed tomography (CT) to assess the effects of chest compressions only during cardiopulmonary resuscitation (CCO-CPR) on alveolar recruitment and haemodynamic parameters in porcine model of ventricular fibrillation. Materials and methods Twelve anaesthetized pigs (26±1kg) were randomly assigned to one of the following groups: (1) intermittent positive pressure ventilation (IPPV) both during basic life support and advanced cardiac life support, or (2) CCO during basic life support and IPPV during advanced cardiac life support. Measurements w…

Evaluation of nitroglycerin effect on remote photoplethysmogram waveform acquired at green and near infra-red illumination

2017

Assessment of skin microcirculation provides diagnostically valuable information during the early stages of pathologies. The simple, cost-effective and intrusive alternative to existing circulation assessment methods is remote photoplethysmography (rPPG). The objective of the present pilot study was to reveal an effect on sublingual administration of 1 mg nitroglycerin on systemic hemodynamic parameters and rPPG waveforms, at 810 nm and 530nm illumination. The protocol comprised 3 minutes of baseline recording, 15 minutes recording of NTG effect, 2 minutes of arterial occlusion and the following 3 min reactive hyperemia. Two PPG signals were acquired from glabrous skin of the middle finger …

2018

Background The aim of our study was to evaluate the feasibility of exercise cardiac magnetic resonance (CMR) in patients with repaired tetralogy of Fallot (RTOF) and to assess right and left ventricular adaptation and aortic wall response to exercise in comparison with volunteers. Methods 11 RTOF and 11 volunteers underwent prospective CMR at rest and during exercise. A supine bicycle ergometer was employed to reach twice the resting heart rate during continuous exercise, blood pressure and heart rate were recorded. Bi-ventricular parameters and aortic stiffness were assessed using accelerated cine sequences and flow-encoding CMR. A t-test was used to compare values between groups. A Mann W…

A peek inside the neurosecretory brain throughOrthopedialenses

2008

The wealth of expression and functional data presented in this overview discloses the homeogene Orthopedia (Otp) as critical for the development of the hypothalamic neuroendocrine system of vertebrates. Specifically, the results depict the up-to-date portrait of the regulation and functions of Otp. The development of neuroendocrine nuclei relies on Otp from fish to mammals, as demonstrated for several peptide and hormone releasing neurons. Additionally, the activity of Otp is essential for the induction of the dopaminergic phenotype in the hypothalamus of vertebrates. Recent insights into the pathways required for Otp regulation have revealed the implication of the main extracellular signal…

Smokeless tobacco, sport and the heart

2014

SummarySmokeless tobacco (snuff) is a finely ground or shredded tobacco that is sniffed through the nose or placed between the cheek and gum. Chewing tobacco is used by putting a wad of tobacco inside the cheek. Smokeless tobacco is widely used by young athletes to enhance performance because nicotine improves some aspects of physiology. However, smokeless tobacco has harmful health effects, including cardiovascular disorders, linked to nicotine physiological effects, mainly through catecholamine release. Nicotine decreases heart rate variability and the ventricular fibrillation threshold, and promotes the occurrence of various arrhythmias; it also impairs endothelial-dependent vasodilation…

Diagnostische Arbeit mit dem Befundbogen der Konfliktachse der OPD-KJ: Empirische Ergebnisse an stationären und ambulanten Patient_innen

2021

Zusammenfassung. In der Kinder- und Jugendlichenpsychiatrie und -psychotherapie findet die Operationalisierte Psychodynamische Diagnostik (OPD-KJ) in den letzten Jahren zunehmend Anwendung. Dieser Beitrag stellt die Konfliktachse der OPD-KJ vor, die eine Operationalisierung von sieben psychodynamischen Konflikten und den jeweils zugeordneten Verarbeitungsmodi enthält. Er beschreibt empirische Ergebnisse zum Vergleich der Konfliktachsenratings und des Strukturratings in einer ambulanten und einer stationären Gruppe von Kindern und Jugendlichen (gesamt N = 186, 12.7 Jahre, 54 % weiblich). Die Befunde zeigen an der Gesamtgruppe, dass die diagnosespezifischen Geschlechtsunterschiede verschwind…

Endothelial function testing and cardiovascular disease: focus on peripheral arterial tonometry

2014

During recent decades, a number of methods have been developed to assess endothelial function, contributing to a better understanding of the pathophysiology of cardiovascular disease. Recently, the advent of noninvasive, reproducible techniques for assessment of endothelial function has opened novel possibilities of application in the clinical setting. Peripheral arterial tonometry is a relatively novel, user-friendly technique measuring finger pulse volume amplitude changes induced by reactive hyperemia following 5 minutes of ischemia in the upper limb. Current evidence indicates that this technique has the potential to significantly impact the field of cardiovascular research and preventi…

Hepatic Sinusoidal Dilatation: A Review of Causes With Imaging-Pathologic Correlation.

2016

Hepatic sinusoids are vascular conduits connecting the portal triad with the central vein. Multiple conditions can lead to sinusoidal dilatation and congestion with resultant stasis of blood within the lumen. The altered hemodynamics associated with hepatic sinusoidal dilatation generally result in heterogeneous enhancement of the hepatic parenchyma on contrast-enhanced computed tomography and magnetic resonance imaging, a pattern often described as “mosaic” enhancement. In this article, we review the causes of hepatic sinusoidal dilatation and the imaging manifestations on contrast-enhanced computed tomography and magnetic resonance.