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Cardiac Resynchronization Therapy
Cardiac resynchronisation therapy (CRT or CRT-P) is the insertion of electrodes in the left and right ventricles of the heart, as well as on occasion the right atrium, to treat heart failure by coordinating the function of the left and right ventricles via a pacemaker, a small device inserted into the anterior chest wall. CRT is indicated in patients with a low ejection fraction (typically 120 ms. The insertion of electrodes into the ventricles is done under local anesthetic, with access to the ventricles most commonly via the subclavian vein, although access may be conferred from the axillary or cephalic veins. Right ventricular access is direct, while left ventricular access is conferred via the coronary sinus (CS). CRT defibrillators (CRT-D) also incorporate the additional function of an implantable cardioverter-defibrillator (ICD), to quickly terminate an abnormally fast, life-threatening heart rhythm. CRT and CRT-D have become increasingly important therapeutic optio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or a gas). In electrochemical cells, electrodes are essential parts that can consist of a variety of materials (chemicals) depending on the type of cell. An electrode may be called either a cathode or anode according to the direction of the electric current, unrelated to the potential difference between electrodes. Michael Faraday coined the term "" in 1833; the word recalls the Greek ἤλεκτρον (, "amber") and ὁδός (, "path, way"). The electrophore, invented by Johan Wilcke in 1762, was an early version of an electrode used to study static electricity. Anode and cathode in electrochemical cells Electrodes are an essential part of any battery. The first electrochemical battery was devised by Alessandro Volta and was aptly named the Voltaic cell. This battery consisted of a stack of copper and zinc electrodes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Institute For Health And Care Excellence
The National Institute for Health and Care Excellence (NICE) is an executive non-departmental public body of the Department of Health and Social Care (United Kingdom), Department of Health and Social Care. As the national health technology assessment body of England, it is responsible for judging the cost-effectiveness of medicines and making them available on the NHS through reimbursement, with its judgements informing decisions in Wales and Northern Ireland. It also provides a range of clinical guidance to the NHS in England and Wales, which are considered by Northern Ireland. History Organisational history It was set up as the National Institute for Clinical Excellence in 1999, and on 1 April 2005 joined with the Health Development Agency to become the new National Institute for Health and Clinical Excellence (still abbreviated as NICE). Following the Health and Social Care Act 2012, NICE was renamed the National Institute for Health and Care Excellence on 1 April ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pericardial Effusion
A pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity. The pericardium is a two-part membrane surrounding the heart: the outer fibrous Connective tissue, connective membrane and an inner two-layered serous membrane. The two layers of the serous membrane enclose the pericardial cavity (the potential space) between them. This pericardial space contains a small amount of pericardial fluid, normally 15-50 mL in volume. The pericardium, specifically the pericardial fluid provides lubrication, maintains the anatomic position of the heart in the chest (levocardia), and also serves as a barrier to protect the heart from infection and inflammation in adjacent tissues and organs. By definition, a pericardial effusion occurs when the volume of fluid in the cavity exceeds the normal limit. If large enough, it can compress the heart, causing cardiac tamponade and obstructive shock. Some of the presenting symptoms are shortness of breath, chest pain, chest pressu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vo2 Max
V̇O2 max (also maximal oxygen consumption, maximal oxygen uptake or maximal aerobic capacity) is the maximum rate of respiration (physiology), oxygen consumption attainable during physical exertion. The name is derived from three abbreviations: "V̇" for volume (the dot over the V indicates "per unit of time" in Newton's notation), "O2" for oxygen, and "max" for maximum and usually normalized per kilogram of body mass. A similar measure is V̇O2 peak (peak oxygen consumption), which is the measurable value from a session of physical exercise, be it incremental or otherwise. It could match or underestimate the actual V̇O2 max. Confusion between the values in older and popular fitness literature is common. The capacity of the lung to exchange oxygen and carbon dioxide is constrained by the rate of blood#Oxygen transport, blood oxygen transport to active tissue. The measurement of V̇O2 max in the laboratory provides a quantitative value of endurance fitness for comparison of i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventricular Remodeling
In cardiology, ventricular remodeling (or cardiac remodeling) refers to changes in the size, shape, structure, and function of the heart. This can happen as a result of exercise (physiological remodeling) or after injury to the heart muscle (pathological remodeling). The injury is typically due to acute myocardial infarction (usually transmural or ST segment elevation infarction), but may be from a number of causes that result in increased pressure or volume, causing pressure overload or volume overload (forms of strain) on the heart. Chronic hypertension, congenital heart disease with intracardiac shunting, and valvular heart disease may also lead to remodeling. After the insult occurs, a series of histopathological and structural changes occur in the left ventricular myocardium that lead to progressive decline in left ventricular performance. Ultimately, ventricular remodeling may result in diminished contractile ( systolic) function and reduced stroke volume. Physiologica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artificial Cardiac Pacemaker
A pacemaker, also known as an artificial cardiac pacemaker, is an implanted medical device that generates electrical pulses delivered by electrodes to one or more of the chambers of the heart. Each pulse causes the targeted chamber(s) to contract and pump blood, thus regulating the function of the electrical conduction system of the heart. The primary purpose of a pacemaker is to maintain an even heart rate Heart rate is the frequency of the cardiac cycle, heartbeat measured by the number of contractions of the heart per minute (''beats per minute'', or bpm). The heart rate varies according to the body's Human body, physical needs, including the nee ..., either because the heart's natural cardiac pacemaker provides an inadequate or irregular heartbeat, or because there is a heart block, block in the heart's electrical conduction system. Modern pacemakers are externally programmable and allow a cardiologist to select the optimal pacing modes for individual patients. Most p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronary Circulation
Coronary circulation is the Circulatory system#Coronary vessels, circulation of blood in the arteries and veins that supply the cardiac muscle, heart muscle (myocardium). Coronary arteries supply oxygen saturation (medicine), oxygenated blood to the heart muscle. #Cardiac veins, Cardiac veins then drain away the blood after it has been deoxygenated. Because the rest of the body, and most especially the brain, needs a steady supply of oxygenated blood that is free of all but the slightest interruptions, the heart is required to function continuously. Therefore its circulation is of major importance not only to its own tissues but to the entire body and even the level of consciousness of the brain from moment to moment. Interruptions of coronary circulation quickly cause heart attacks (myocardial infarctions), in which the heart muscle is damaged by hypoxia (medical), oxygen starvation. Such interruptions are usually caused by coronary ischemia linked to coronary artery disease, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venography
Venography (also called phlebography or ascending phlebography) is a procedure in which an X-ray of the veins, a venogram, is taken after a special dye is injected into the bone marrow or veins. The dye has to be injected constantly via a catheter, making it an invasive procedure. Normally the catheter is inserted by the groin and moved to the appropriate site by navigating through the vascular system. Contrast venography is the gold standard for judging diagnostic imaging methods for deep vein thrombosis; although, because of its cost, invasiveness, and other limitations, this test is rarely performed. Venography can also be used to distinguish blood clots from obstructions in the veins, to evaluate congenital vein problems, to see how the deep leg vein valves are working, or to identify a vein for arterial bypass grafting. Areas of the venous system that can be investigated include the lower extremities, the inferior vena cava, and the upper extremities. The United States Na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contrast Agent
A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radiopharmaceuticals, which emit radiation themselves. In X-ray imaging, contrast agents enhance the radiodensity in a target tissue or structure. In magnetic resonance imaging (MRI), contrast agents shorten (or in some instances increase) the relaxation times of nuclei within body tissues in order to alter the contrast in the image. Contrast agents are commonly used to improve the visibility of blood vessels and the gastrointestinal tract. The types of contrast agent are classified according to their intended imaging modalities. Radiocontrast media For radiography, which is based on X-rays, iodine and barium are the most common types of contrast agent. Various sorts of iodinated contrast agents exist, with variations occurring between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catheter
In medicine, a catheter ( ) is a thin tubing (material), tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Catheters are manufactured for specific applications, such as cardiovascular, urological, gastrointestinal, neurovascular and ophthalmic procedures. The process of inserting a catheter is called ''catheterization''. In most uses, a catheter is a thin, flexible tube (''soft'' catheter) though catheters are available in varying levels of stiffness depending on the application. A catheter left inside the body, either temporarily or permanently, may be referred to as an "indwelling catheter" (for example, a peripherally inserted central catheter). A permanently inserted catheter may be referred to as a "permcath" (originally a trademark). Catheters can be inserted into a body cavity, duct, or vessel, brain, skin or adipose tissue. Functional ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asystole
Asystole (New Latin, from Greek privative a "not, without" + ''systolē'' "contraction") is the absence of ventricular contractions in the context of a lethal heart arrhythmia (in contrast to an induced asystole on a cooled patient on a heart-lung machine and general anesthesia during surgery necessitating stopping the heart). Asystole is the most serious form of cardiac arrest and is usually irreversible. Also referred to as cardiac flatline, asystole is the state of total cessation of electrical activity from the heart, which means no tissue contraction from the heart muscle and therefore no blood flow to the rest of the body. Asystole should not be confused with very brief pauses below 3 seconds in the heart's electrical activity that can occur in certain less severe abnormal rhythms. Asystole is different from very fine occurrences of ventricular fibrillation, though both have a poor prognosis, and untreated fine VF will lead to asystole. Faulty wiring, disconnection of electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Conduction System Of The Heart
The cardiac conduction system (CCS, also called the electrical conduction system of the heart) transmits the Cardiac action potential, signals generated by the sinoatrial node – the heart's Cardiac pacemaker, pacemaker, to cause the heart muscle to Muscle contraction, contract, and pump blood through the body's circulatory system. The Cardiac pacemaker, pacemaking signal travels through the right atrium to the atrioventricular node, along the bundle of His, and through the bundle branches to Purkinje fibers in the Ventricle (heart), walls of the ventricles. The Purkinje fibers transmit the signals more rapidly to stimulate contraction of the ventricles. The conduction system consists of specialized Cardiomyocyte, heart muscle cells, situated within the myocardium. There is a cardiac skeleton, skeleton of fibrous tissue that surrounds the conduction system which can be seen on an ECG. Dysfunction of the conduction system can cause Heart arrhythmia, irregular heart rhythms includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
