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Pulse Duplicator
A pulse duplicator is a device used to duplicate the pulsing flow of the human heart and the associated hemodynamics. It is used to research the conditions of heart disease. Pulse duplicators can be used to conduct in vitro or ex vivo testing. Common uses include testing new artificial heart valves and simulating procedures like transcatheter aortic valve replacement. Design A pulse duplicator replicates parts of the circulatory system. Many pulse duplicators model only half the heart, commonly the left atrium and ventricle, in order to test the mitral and aortic valves. A common design to model the heart uses a piston to simulate the contraction and expansion of the heart. An alternate design uses a flexible plastic heart model, or an ex vivo heart, and applies hydraulic pressure to induce contraction and expansion. The circulatory system blood vessels are typically modeled using tubing. Compliance chambers and narrow tubing can be used to model the Windkessel e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piston Pulse Duplicator
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder. __TOC__ Piston engines Internal combustion engines An internal combustion engine is acted upon by the pressure of the expanding combustion gases in the combustion chamber space at the top of the cylinder. This force then acts downwards through the connecting rod and onto the crankshaft. The connecting rod is attached t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemodynamics
Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms of autoregulation, just as hydraulic circuits are controlled by control systems. The hemodynamic response continuously monitors and adjusts to conditions in the body and its environment. Hemodynamics explains the physical laws that govern the flow of blood in the blood vessels. Blood flow ensures the transportation of nutrients, hormones, metabolic waste products, oxygen, and carbon dioxide throughout the body to maintain cell-level metabolism, the regulation of the pH, osmotic pressure and temperature of the whole body, and the protection from microbial and mechanical harm. Blood is a non-Newtonian fluid, and is most efficiently studied using rheology rather than hydrodynamics. Because blood vessels are not rigid tubes, classic hydrodynamics and fluids mechanics based on the use of classical viscometers are not capable of explaining haemodynamics. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Vitro
''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology and its subdisciplines are traditionally done in labware such as test tubes, flasks, Petri dishes, and microtiter plates. Studies conducted using components of an organism that have been isolated from their usual biological surroundings permit a more detailed or more convenient analysis than can be done with whole organisms; however, results obtained from ''in vitro'' experiments may not fully or accurately predict the effects on a whole organism. In contrast to ''in vitro'' experiments, ''in vivo'' studies are those conducted in living organisms, including humans, known as clinical trials, and whole plants. Definition ''In vitro'' (Latin language, Latin for "in glass"; often not italicized in English usage) studies are conducted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ex Vivo
refers to biological studies involving tissues, organs, or cells maintained outside their native organism under controlled laboratory conditions. By carefully managing factors such as temperature, oxygenation, nutrient delivery, and perfusing a nutrient solution through the tissue's vasculature, researchers sustain function long enough to conduct experiments that would be difficult or unethical in a living body. ''Exvivo'' models occupy a middle ground between '' in vitro'' () models, which typically use isolated cells, and '' in vivo'' () studies conducted inside living organisms, offering both experimental control and physiological relevance. ''Ex vivo'' platforms support pharmacologic screening, toxicology testing, transplant evaluation, developmental biology, and investigations of disease-mechanism research across medicine and biology, from cardiology and neuroscience to dermatology and orthopedics. Because they often use human tissues obtained from clinical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artificial Heart Valves
An artificial heart valve is a one-way valve implanted into a person's heart to replace a heart valve that is not functioning properly (valvular heart disease). Artificial heart valves can be separated into three broad classes: mechanical heart valves, bioprosthetic tissue valves and engineered tissue valves. The human heart contains four valves: tricuspid valve, pulmonary valve, mitral valve and aortic valve. Their main purpose is to keep blood flowing in the proper direction through the heart, and from the heart into the major blood vessels connected to it (the pulmonary artery and the aorta). Heart valves can malfunction for a variety of reasons, which can impede the flow of blood through the valve (stenosis) and/or let blood flow backwards through the valve ( regurgitation). Both processes put strain on the heart and may lead to serious problems, including heart failure. While some dysfunctional valves can be treated with drugs or repaired, others need to be replaced with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcatheter Aortic Valve Replacement
Transcatheter aortic valve replacement (TAVR) is the implantation of the aortic valve of the heart through the blood vessels without actual removal of the native valve (as opposed to the aortic valve replacement by open heart surgery, surgical aortic valve replacement, AVR). The first TAVI was performed on 16 April 2002 by Alain Cribier, which became a new alternative in the management of high-risk patients with severe aortic stenosis. The implantated valve is delivered via one of several access methods: transfemoral (in the upper leg), transapical (through the wall of the heart), subclavian (beneath the collar bone), direct aortic (through a minimally invasive surgical incision into the aorta), and transcaval (from a temporary hole in the aorta near the navel through a vein in the upper leg), among others. Severe symptomatic aortic stenosis carries a poor prognosis. At present, there is no treatment via medication, making the timing of aortic valve replacement the most importa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitral
The mitral valve ( ), also known as the bicuspid valve or left atrioventricular valve, is one of the four heart valves. It has two Cusps of heart valves, cusps or flaps and lies between the atrium (heart), left atrium and the ventricle (heart), left ventricle of the heart. The heart valves are all one-way valves allowing blood flow in just one direction. The mitral valve and the tricuspid valve are known as the Heart valve#Atrioventricular valves, atrioventricular valves because they lie between the atria and the ventricles. In normal conditions, blood flows through an open mitral valve during diastole with contraction of the left atrium, and the mitral valve closes during systole with contraction of the left ventricle. The valve opens and closes because of pressure differences, opening when there is greater pressure in the left atrium than ventricle and closing when there is greater pressure in the left ventricle than atrium. In abnormal conditions, blood may flow backward thro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aortic Valves
The aortic valve is a valve in the heart of humans and most other animals, located between the left ventricle and the aorta. It is one of the four valves of the heart and one of the two semilunar valves, the other being the pulmonary valve. The aortic valve normally has three cusps or leaflets, although in 1–2% of the population it is found to congenitally have two leaflets. The aortic valve is the last structure in the heart the blood travels through before stopping the flow through the systemic circulation. Structure The aortic valve normally has three cusps however there is some discrepancy in their naming. They may be called the left coronary, right coronary and non-coronary cusp. Some sources also advocate they be named as a left, right and posterior cusp. Anatomists have traditionally named them the left posterior (origin of left coronary), anterior (origin of the right coronary) and right posterior. The three cusps, when the valve is closed, contain a sinus called an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
