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Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
For suspected subarachnoid haemorrhage CT should be performed ideally within 6 hours of onset of symptoms [24], during which period the sensitivity for detection approaches 100%, although it remains high for 2–3 days. After that sensitivity decreases progressively and post 5–7 days lumbar puncture will often be required for diagnosis (by demonstrating xanthochromia in the CSF). MRI is able to detect subarachnoid haemorrhage but in the acute phase CT is usually easier to perform; it may have a role if imaging is delayed [25], and thus reduce the need for the unpleasant lumbar puncture. CT angiography may also be used to detect the underlying aneurysm if present.
Elements of Continuum Mechanics
Published in Clement Kleinstreuer, Biofluid Dynamics, 2016
Causes of aneurysms are still speculative, but they may include arteriosclerosis, atheroma, congenital defects, hypertension, smoking, hereditary conditions, obesity, abnormal blood flow, etc. (see Salsac et al., 2004). Clearly, hemodynamics, biomechanical factors, and biochemical processes play key roles in the genesis of an aneurysm.
Mathematical investigation of drug dispersion in the blood flow through Stenotic-Aneurysm tapered blood vessel
Published in International Journal of Modelling and Simulation, 2023
J V Ramana Reddy, Hojin Ha, S Sundar
Blood vessels play a crucial function in the circulatory system. They are passages that carry blood from the heart to all areas of the body and back, as well as from the heart to the lungs and back. Arteries vary greatly in diameter across different types, with their size range typically spanning from approximately less than to [4]. An artery is a blood vessel that transports oxidized blood away from the heart, whereas a vein is a blood channel that transports blood toward the heart. The lumen of the arteries is nearly spherical, but the lumen of the veins is uneven and frequently collapses. Blood flow simulation for a patient-specific type-B aortic dissection investigates the effects of anti-hypertensive drugs on hemodynamic metrics [5]. In contrast to arteries, veins are thin-walled vessels with a wide and irregular lumen. Diseases of the arteries, veins, and lymph vessels indicate blood flow abnormalities that influence circulation, causing organ function to be disrupted. An aneurysm is a pathological condition that weakens the wall of a blood artery due to the bulging region, resulting in an abnormal widening or ballooning of more than 50% of the standard diameter [6]. Arteries are more vulnerable to aneurysms than veins among the many blood vessels.
Prediction of the Probability and Risk Factors of Early Abdominal Aortic Aneurysm Using the Gradient Boosted Decision Trees Model
Published in Applied Artificial Intelligence, 2022
Abdominal aortic aneurysms (AAA) are the most common aortic aneurysms, which often present as aneurysmal dilatation of the infrarenal abdominal aorta. It is defined as blood vessel expansion larger than 3 cm diameter or more than 1.5-times of the normal aortic diameter(Li et al. 2019). The prevalence of abdominal aortic aneurysms (AAAs) in the Western population has been well reported and ranges from 4% to 7.2%(Ashton et al. 2002; Chan et al. 2021; Lindholt et al. 2005; Norman et al. 2004; Scott et al. 1995). The overall AAA prevalence was 1.3% in the Asian population(Chan et al. 2021). Although the prevalence of AAA is low, the mortality of AAA is very high. Most AAA patients have no obvious symptoms; however, with increasing aneurysm diameter, the risk of rupture increases significantly. The mortality of patients with a ruptured aneurysm is extremely high, most patients died before they arrived at the hospital, and the mortality is over 80%(Mik et al. 2019). Therefore, early diagnosis, regular follow-up and timely treatment is very important for AAA.
The evolution of stent grafts for endovascular repair of abdominal aortic aneurysms: how design changes affect clinical outcomes
Published in Expert Review of Medical Devices, 2019
Blake R. Bewley, Andrew B. Servais, Payam Salehi
An Abdominal Aortic Aneurysm (AAA) is a life-threatening condition that results from the weakening and ballooning of the aortic wall above the Common iliac arteries. A total of 200,000 people are diagnosed with this condition every year in the United States alone and it is the 15th leading cause of death in the US. This affliction is particularly prevalent in men over 65 with a history of smoking [1]. As the aortic aneurysm expands, the risk of rupture and fatal hemorrhage increase. Thus, once an aneurysm has reached a certain diameter (5.5 cm in men, 5 cm in women) intervention is warranted to avoid rupture. The standard treatment for all AAA prior to the advent of specialized endografts was open surgical repair, which carries the cost of longer hospital stay, increased blood loss during the procedure, greater postoperative recovery time, and a higher risk for short-term mortality and morbidity. In his landmark study, Parodi demonstrated the feasibility of utilizing stent grafts to bypass the bloated aorta, paving the way for the development of a new treatment approach that was significantly less invasive as well as being potentially less expensive [2]. While Parodi designed custom grafts for the patients in his initial study, the market is now flooded with multiple endografts from various manufacturers who are constantly attempting to improve clinical outcomes, increase accuracy and versatility of the delivery and implantation system, and overcome hostile patient anatomy. This paper will look at the way in which stent grafts designed for abdominal aortic Endovascular Aneurysm Repair (EVAR) have improved over time and the design changes that have facilitated more favorable clinical outcomes.