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Vectorcardiography
Vectorcardiography (VCG) is a method of recording the magnitude and direction of the electrical forces that are generated by the heart by means of a continuous series of vectors that form curving lines around a central point. Vectorcardiography was developed by E. Frank in the mid 1950s. Since the human body is a three-dimensional structure, the basic idea is to construct three orthogonal leads containing all the electric information. The three leads are represented by right-left axis (X), head-to-feet axis (Y) and front-back (anteroposterior) axis (Z). To calculate Frank's leads X, Y and Z using the standard leads system, the following expressions are used: X = -(-0.172 V1 - 0.074 V2 + 0.122 V3 + 0.231 V4 + 0.239 V5 + 0.194 V6 + 0.156 DI - 0.010 DII) (1) Y = (0.057 V1 - 0.019 V2 - 0.106 V3 - 0.022 V4 + 0.041 V5 + 0.048 V6 - 0.227 DI + 0.887 DII) (2) Z = -(-0.229 V1 - 0.310 V2 - 0.246 V3 - 0.063 V4 + 0.055 V5 + 0.108 V6 + 0.022 DI + 0.102 DII) (3) Researchers have developed v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Electrocardiology
The ''Journal of Electrocardiology'' is a peer-reviewed medical journal covering electrocardiography, vectorcardiography, cardiac arrhythmias, membrane action potential, cardiac pacing, monitoring defibrillation, instrumentation, drug effects, and computer applications. It is the official journal of the International Society for Computerized Electrocardiology and the International Society of Electrocardiology. Abstracting and indexing The journal is abstracted and indexed in: * Current Contents/Clinical Medicine * EMBASE * Index Medicus/MEDLINE/PubMed * Science Citation Index * Scopus According to the ''Journal Citation Reports'', the journal has a 2013 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious or important within their field. The Impact Factor of a journa ... of 1.363. References External links * Cardiology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart
The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the thorax, chest, called the mediastinum. In humans, the heart is divided into four chambers: upper left and right Atrium (heart), atria and lower left and right Ventricle (heart), ventricles. Commonly, the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. In a healthy heart, blood flows one way through the heart due to heart valves, which prevent cardiac regurgitation, backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a sma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ST Depression
ST depression refers to a finding on an electrocardiogram, wherein the trace in the ST segment is abnormally low below the baseline. Causes It is often a sign of myocardial ischemia, of which coronary insufficiency is a major cause. Other ischemic heart diseases causing ST depression include: * Subendocardial ischemia or even infarction. Subendocardial means non full thickness ischemia. In contrast, ST elevation is transmural (or full thickness) ischemia * Non Q-wave myocardial infarction * Reciprocal changes in acute Q-wave myocardial infarction (e.g., ST depression in leads I & aVL with acute inferior myocardial infarction) * ST segment depression and T-wave changes may be seen in patients with unstable angina Depressed but ''upsloping'' ST segment generally rules out ischemia as a cause. Also, it can be a normal variant or artifacts, such as: * Pseudo-ST-depression, which is a wandering baseline due to poor skin contact of the electrode MicroEKG ManualRetrieved September ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Left Ventricular Hypertrophy
Left ventricular hypertrophy (LVH) is thickening of the heart muscle of the left ventricle of the heart, that is, left-sided ventricular hypertrophy and resulting increased left ventricular mass. Causes While ventricular hypertrophy occurs naturally as a reaction to aerobic exercise and strength training, it is most frequently referred to as a pathological reaction to cardiovascular disease, or high blood pressure. It is one aspect of ventricular remodeling. While LVH itself is not a disease, it is usually a marker for disease involving the heart. Disease processes that can cause LVH include any disease that increases the afterload that the heart has to contract against, and some primary diseases of the muscle of the heart. Causes of increased afterload that can cause LVH include aortic stenosis, aortic insufficiency and hypertension. Primary disease of the muscle of the heart that cause LVH are known as hypertrophic cardiomyopathies, which can lead into heart failure. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infarction
Infarction is tissue death (necrosis) due to Ischemia, inadequate blood supply to the affected area. It may be caused by Thrombosis, artery blockages, rupture, mechanical compression, or vasoconstriction. The resulting lesion is referred to as an infarct (from the Latin ''infarctus'', "stuffed into"). Causes Infarction occurs as a result of prolonged ischemia, which is the insufficient supply of oxygen and nutrition to an area of tissue due to a disruption in blood supply. The blood vessel supplying the affected area of tissue may be blocked due to an obstruction in the vessel (e.g., an arterial embolus, thrombus, or atherosclerotic plaque), compressed by something outside of the vessel causing it to narrow (e.g., tumor, volvulus, or hernia), ruptured by trauma causing a loss of blood pressure downstream of the rupture, or vasoconstricted, which is the narrowing of the blood vessel by contraction of the muscle wall rather than an external force (e.g., cocaine vaso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiac Death
Clinical death is the medical term for cessation of blood circulation and breathing, the two criteria necessary to sustain the lives of human beings and of many other organisms. It occurs when the heart stops beating in a regular rhythm, a condition called cardiac arrest. The term is also sometimes used in resuscitation research. Stopped blood circulation has historically proven irreversible in most cases. Prior to the invention of cardiopulmonary resuscitation (CPR), defibrillation, epinephrine injection, and other treatments in the 20th century, the absence of blood circulation (and vital functions related to blood circulation) was historically considered the official definition of death. With the advent of these strategies, cardiac arrest came to be called ''clinical death'' rather than simply ''death'', to reflect the possibility of post-arrest resuscitation. At the onset of clinical death, consciousness is lost within several seconds, and in dogs, measurable brain activity has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Pressure
Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" refers to the pressure in a brachial artery, where it is most commonly measured. Blood pressure is usually expressed in terms of the systolic pressure (maximum pressure during one Cardiac cycle, heartbeat) over diastolic pressure (minimum pressure between two heartbeats) in the cardiac cycle. It is measured in Millimetre of mercury, millimetres of mercury (mmHg) above the surrounding atmospheric pressure, or in Pascal (unit), kilopascals (kPa). The difference between the systolic and diastolic pressures is known as pulse pressure, while the average pressure during a cardiac cycle is known as mean arterial pressure. Blood pressure is one of the vital signs—together with respiratory rate, heart rate, Oxygen saturation (me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypertension
Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms itself. It is, however, a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, vision loss, chronic kidney disease, and dementia. Hypertension is a major cause of premature death worldwide. High blood pressure is classified as essential hypertension, primary (essential) hypertension or secondary hypertension. About 90–95% of cases are primary, defined as high blood pressure due to non-specific lifestyle and Genetics, genetic factors. Lifestyle factors that increase the risk include excess salt in the diet, overweight, excess body weight, smoking, physical inactivity and Alcohol (drug), alcohol use. The remaining 5–10% of cases are categorized as secondary hypertension, d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QT Prolongation
QT or Qt may refer to: Businesses * The Qt Company, a Finnish software developer * QT Hotels & Resorts, an Australasian hospitality provider * QT Inc., an American bracelet manufacturer * QuikTrip, an American convenience store chain People * QT (musician) (born 1988), American pop singer * QTCinderella (born 1994), American Twitch streamer and YouTuber * Q-Tee, British rapper (active in the 1990s) * Quentin Tarantino (born 1963), American filmmaker Science and technology Computer software * Qt (software), a cross-platform application framework * QuickTime, a multimedia technology from Apple Inc. Heart medicine * QT interval, on an electrocardiogram ** Long QT syndrome, a rare condition ** Short QT syndrome, a very rare disease Units of measure * Quart (qt), an imperial unit of volume Television shows * '' QT: QueerTelevision'', a 1990s Canadian LGBT newsmagazine * ''Question Time'' (TV programme), a British panel debate (first aired 1979) Transport * QT (New York City ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Channel
Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by Gating (electrophysiology), gating the flow of ions across the cell membrane, controlling the flow of ions across secretion, secretory and epithelial cells, and regulating cell (biology), cell volume. Ion channels are present in the membranes of all cells. Ion channels are one of the two classes of ionophore, ionophoric proteins, the other being ion transporters. The study of ion channels often involves biophysics, electrophysiology, and pharmacology, while using techniques including voltage clamp, patch clamp, immunohistochemistry, X-ray crystallography, fluoroscopy, and RT-PCR. Their classification as molecules is referred to as channelomics. Basic features There are two distinctive features of ion channels that differentiate them from other types of ion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vector (mathematics And Physics)
In mathematics and physics, vector is a term that refers to physical quantity, quantities that cannot be expressed by a single number (a scalar (physics), scalar), or to elements of some vector spaces. Historically, vectors were introduced in geometry and physics (typically in mechanics) for quantities that have both a magnitude and a direction, such as displacement (geometry), displacements, forces and velocity. Such quantities are represented by geometric vectors in the same way as distances, masses and time are represented by real numbers. The term ''vector'' is also used, in some contexts, for tuples, which are finite sequences (of numbers or other objects) of a fixed length. Both geometric vectors and tuples can be added and scaled, and these vector operations led to the concept of a vector space, which is a set (mathematics), set equipped with a vector addition and a scalar multiplication that satisfy some axioms generalizing the main properties of operations on the abov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Repolarization
In neuroscience, repolarization refers to the change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential which has changed the membrane potential to a positive value. The repolarization phase usually returns the membrane potential back to the resting membrane potential. The efflux of potassium (K+) ions results in the falling phase of an action potential. The ions pass through the selectivity filter of the K+ channel pore. Repolarization typically results from the movement of positively charged K+ ions out of the cell. The repolarization phase of an action potential initially results in hyperpolarization, attainment of a membrane potential, termed the afterhyperpolarization, that is more negative than the resting potential. Repolarization usually takes several milliseconds. Repolarization is a stage of an action potential in which the cell experiences a decrease of voltage due to the efflux of potassium (K+) io ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
