Search results for "Artery"

Non-invasive determination of cardiac output by transesophageal Doppler ultrasound-clinical application and validation

2003

The authors describe the development and validation of a device using transesophageal (TE) Doppler ultrasound to provide continuous and noninvasive monitoring of cardiac output (CO) and related parameters. In intubated and artificially ventilated patients who underwent pulmonary artery catherization for hemodynamic monitoring, CO was determined by the esophageal Doppler ultrasound probe and compared to the results obtained simultaneously by means of thermodilution. A very close correlation was found between the results (r=0.99), with a standard estimate of error less than 5% as well as good reproducibility (r=0.96 and r=0.98). >

Microaneurysm detection with radon transform-based classification on retina images.

2012

The creation of an automatic diabetic retinopathy screening system using retina cameras is currently receiving considerable interest in the medical imaging community. The detection of microaneurysms is a key element in this effort. In this work, we propose a new microaneurysms segmentation technique based on a novel application of the radon transform, which is able to identify these lesions without any previous knowledge of the retina morphological features and with minimal image preprocessing. The algorithm has been evaluated on the Retinopathy Online Challenge public dataset, and its performance compares with the best current techniques. The performance is particularly good at low false p…

Short-Time Ocular Ischemia Induces Vascular Endothelial Dysfunction and Ganglion Cell Loss in the Pig Retina

2019

Visual impairment and blindness are often caused by retinal ischemia-reperfusion (I/R) injury. We aimed to characterize a new model of I/R in pigs, in which the intraocular pathways were not manipulated by invasive methods on the ocular system. After 12 min of ischemia followed by 20 h of reperfusion, reactivity of retinal arterioles was measured in vitro by video microscopy. Dihydroethidium (DHE) staining, qPCR, immunohistochemistry, quantification of neurons in the retinal ganglion cell layer, and histological examination was performed. Retinal arterioles of I/R-treated pigs displayed marked attenuation in response to the endothelium-dependent vasodilator, bradykinin, compared to sham-tre…

Role of nitric oxide synthase isoforms for ophthalmic artery reactivity in mice.

2014

Abstract Nitric oxide synthases (NOS) are involved in regulation of ocular vascular tone and blood flow. While endothelial NOS (eNOS) has recently been shown to mediate endothelium-dependent vasodilation in mouse retinal arterioles, the contribution of individual NOS isoforms to vascular responses is unknown in the retrobulbar vasculature. Moreover, it is unknown whether the lack of a single NOS isoform affects neuron survival in the retina. Thus, the goal of the present study was to examine the hypothesis that the lack of individual nitric oxide synthase (NOS) isoforms affects the reactivity of mouse ophthalmic arteries and neuron density in the retinal ganglion cell (RGC) layer. Mice defi…

2017

Background Patients with retinal vascular occlusion disease have an increased risk for ischemic stroke and share some risk factors with cerebrovascular disease. The purpose of this study was to analyze the prevalence of atrial fibrillation (AF) in subjects with retinal vascular occlusive disease and anterior ischemic optic neuropathy and to compare these data to an ischemic stroke group. Methods Prospective, observational single-center trial. Subjects with retinal artery occlusion (RAO), retinal vein occlusion (RVO) and anterior ischemic optic neuropathy (AION) were included. Patients with ischemic stroke (IS) from a previous observational trial were used as control. Investigation included …

Therapeutic modulation of lipoprotein-associated phospholipase A2 (Lp-PLA2)

2011

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a calcium-independent phospholipase A2 that circulates in plasma in association with lipoprotein particles, whereas in atherosclerotic plaques it is co-localized with macrophages. Lp-PLA2 generates two proinflammatory mediators, lysophosphatidylcholine and oxidized nonesterified fatty acids, which play a role in the development of atherosclerotic lesions and formation of a necrotic core, leading to more vulnerable plaques. Epidemiologic studies demonstrate that increased circulating levels of Lp-PLA2 predict an increased risk of myocardial infarction, stroke and cardiovascular mortality. Furthermore, histologic examination of diseased hum…

Comparison of the strain field of abdominal aortic aneurysm measured by magnetic resonance imaging and stereovision: a feasibility study for predicti…

2015

International audience; The prediction of the risk of rupture of abdominal aortic aneurysm (AAA) is a complex problem. Currently the criteria to predict rupture of abdominal aortic aneurysms are aneurysm diameter and growth rates. It is generally believed that study of the wall strain distribution could be helpful to find a better decision criterion for surgery of aortic aneurysms before their rupture. The wall strain distribution depends on many biological and biomechanical factors such as elastic properties of the aorta, turbulent blood flow, anatomy of the aorta, presence of thrombus or not and so on. Recently, numerical simulations to estimate rupture-potential have received many attent…

Severity of Asymptomatic Carotid Stenosis and Risk of Ipsilateral Hemispheric Ischaemic Events: Results from the ACSRS Study

2005

Objectives. This study determines the risk of ipsilateral ischaemic neurological events in relation to the degree of asymptomatic carotid stenosis and other risk factors. Methods. Patients (n = 1115) with asymptomatic internal carotid artery (ICA) stenosis greater than 50% in relation to the bulb diameter were followed up for a period of 6-84 (mean 37.1) months. Stenosis was graded using duplex, and clinical and biochemical risk factors were recorded. Results. The relationship between ICA stenosis and event rate is linear when stenosis is expressed by the ECST method, but S-shaped if expressed by the NASCET method. In addition to the ECST grade of stenosis (RR 1.6; 95% CI 1.21-2.15), histor…

Management of Complex Cerebral Aneurysms

2022

BACKGROUND: Complex intracranial aneurysms (CIAs) are challenging pathologies to treat. Characteristics making an aneurysm complex include dimension, history of previous treatment, location, absence of collateral circulation, intraluminal thrombosis, and calcification of the wall. The goal of the therapeutic process is to exclude the malformation from the cerebral circulation and both endovascular and surgical treatments are valid procedures.METHODS: Between 1990 and 2020, 170 CIAs were treated at our institution (33 ruptured, 137 unruptured). They were 3 prepetrous segment of the internal carotid artery (ICA), 14 purely intracavernous sinus, 27 intracavernous with subarachnoid extension, 6…

Does velocity of dilatation influence the result of dilatation? A postmortem study.

1988

We evaluated the influence of velocity of dilatation on the success of and the vascular damage produced by dilatation. Nonatheroslerotic segments of distal superficial femoral arteries were dilated "fast" (n = 69) or "slow" (n = 45) under standard conditions with balloon catheters. The arterial wall was overstretched between 1% and more than 60%. The success of dilatation rose continuously with increasing overstretching during dilatation. The damage to the arterial wall by dilatation increased discontinuously with increasing overstretching. Dilatation success and damage patterns did not differ in the "slow" and "fast" groups.