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Antiarrhythmics
Antiarrhythmic agents, also known as cardiac dysrhythmia medications, are a group of pharmaceuticals that are used to suppress abnormally fast rhythms ( tachycardias), such as atrial fibrillation, supraventricular tachycardia and ventricular tachycardia. Many attempts have been made to classify antiarrhythmic agents. Many of the antiarrhythmic agents have multiple modes of action, which makes any classification imprecise. Vaughan Williams classification The Vaughan Williams classification was introduced in 1970 by Miles Vaughan Williams.Vaughan Williams, EM (1970) "Classification of antiarrhythmic drugs". In ''Symposium on Cardiac Arrhythmias'' (Eds. Sandoe E; Flensted-Jensen E; Olsen KH). Astra, Elsinore. Denmark (1970) Vaughan Williams was a pharmacology tutor at Hertford College, Oxford. One of his students, Bramah N. Singh, contributed to the development of the classification system. The system is therefore sometimes known as the Singh-Vaughan Williams classification. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quinidine
Quinidine is a class IA antiarrhythmic agent used to treat heart rhythm disturbances. It is the enantiomer of antimalarial agent quinine, originally derived from the bark of the cinchona tree. The drug causes increased action potential duration, as well as a prolonged QT interval. As of 2019, its IV formulation is no longer being manufactured for use in the United States. Medical uses Quinidine is occasionally used as a class I antiarrhythmic agent to prevent ventricular arrhythmias, particularly in Brugada Syndrome, although its safety in this indication is uncertain. It reduces the recurrence of atrial fibrillation after patients undergo cardioversion, but it has proarrhythmic effects and trials suggest that it may lead to an overall increased mortality in these patients. Quinidine is also used to treat short QT syndrome. Eli Lilly has discontinued manufacture of parenteral quinidine gluconate in the US, and its future availability in many countries is uncertain. Other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiac Action Potential
The cardiac action potential is a brief change in voltage ( membrane potential) across the cell membrane of heart cells. This is caused by the movement of charged atoms (called ions) between the inside and outside of the cell, through proteins called ion channels. The cardiac action potential differs from action potentials found in other types of electrically excitable cells, such as nerves. Action potentials also vary within the heart; this is due to the presence of different ion channels in different cells. Unlike the action potential in skeletal muscle cells, the cardiac action potential is not initiated by nervous activity. Instead, it arises from a group of specialized cells known as pacemaker cells, that have automatic action potential generation capability. In healthy hearts, these cells form the cardiac pacemaker and are found in the sinoatrial node in the right atrium. They produce roughly 60–100 action potentials every minute. The action potential passes along t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Procainamide
Procainamide (PCA) is a medication of the antiarrhythmic class used for the treatment of cardiac arrhythmias. It is classified by the Vaughan Williams classification system as class Ia; thus it is a sodium channel blocker of cardiomyocytes. In addition to blocking the ''I''Na current, it inhibits the ''I''Kr rectifier K+ current. Procainamide is also known to induce a voltage-dependent open channel block on the batrachotoxin (BTX)-activated sodium channels in cardiomyocytes. Uses Medical Procainamide is used for treating ventricular arrhythmias: ventricular ectopy and tachycardia and supraventricular arrhythmias: atrial fibrillation, and re-entrant and automatic supraventricular tachycardia. For example, it can be used to convert new-onset atrial fibrillation, and although was initially thought to be suboptimal for this purpose, a growing body of literature is amounting in support for this exact cause. It is administered by mouth, by intramuscular injection, or intravenously. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encainide
Encainide (trade name Enkaid) is a class Ic antiarrhythmic agent. It is no longer used because of its frequent proarrhythmic side effects. Synthesis See also * Iferanserin * Cardiac Arrhythmia Suppression Trial The Cardiac Arrhythmia Suppression Trial (CAST) was a double-blind, randomized, controlled study designed to test the hypothesis that suppression of premature ventricular complexes (PVC) with class I antiarrhythmic agents after a myocardial infarc ... References Antiarrhythmic agents Benzanilides Phenol ethers Piperidines Sodium channel blockers Withdrawn drugs {{cardiovascular-drug-stub ... [...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 in the heart's electrical activity—even those that produce a temporary flatline—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. Fault ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myocardial Infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may travel into the shoulder, arm, back, neck or jaw. Often it occurs in the center or left side of the chest and lasts for more than a few minutes. The discomfort may occasionally feel like heartburn. Other symptoms may include shortness of breath, nausea, feeling faint, a cold sweat or feeling tired. About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure, an irregular heartbeat, cardiogenic shock or cardiac arrest. Most MIs occur due to coronary artery disease. Risk factors include high blood pressure, smoking, diabetes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tocainide
Tocainide (Tonocard) is a class Ib antiarrhythmic agent. It is no longer sold in the United States. Pharmacokinetics Tocainide is a lidocaine analog, that does not have significant 1st pass metabolism. It is found in two enantiomer In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...s. The R isomer is 4x as potent as the S. Oral bioavailability is 0.9-1.0. In the blood tocainide is 10-20% protein bound. The Volume of distribution is 2.5-3.5 L/kg. 30-50% is excreted unchanged in the urine. The more active R-isomer is cleared faster in anephric patients or those with severe renal dysfunction. The main metabolite is the glucuronidated tocainide carbamic acid. The glucuronosyl transferase is apparently induced by rifampin. Weak inhibition of Cyp1A2 leads to a mild theophylline int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mexiletine
Mexiletine (INN) (sold under the brand names Mexitil and Namuscla) is a medication used to treat abnormal heart rhythms, chronic pain, and some causes of muscle stiffness. Common side effects include abdominal pain, chest discomfort, drowsiness, headache, and nausea. It works as a non-selective voltage-gated sodium channel blocker and belongs to the Class IB group of anti-arrhythmic medications. Medical uses Mexiletine has several uses including the treatment of abnormal heart rhythms or arrhythmias, chronic pain, and myotonia. In general when treating arrhythmias, mexiletine is reserved for use in dangerous heart rhythm disturbances such as ventricular tachycardia. It is of particular use when treating arrhythmias caused by long QT syndrome. The LQT3 form of long QT syndrome is amenable to treatment with mexiletine as this form is caused by defective sodium channels that continue to release a sustained current rather than fully inactivating, however other forms of long QT ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenytoin
Phenytoin (PHT), sold under the brand name Dilantin among others, is an anti-seizure medication. It is useful for the prevention of tonic-clonic seizures (also known as grand mal seizures) and focal seizures, but not absence seizures. The intravenous form, fosphenytoin, is used for status epilepticus that does not improve with benzodiazepines. It may also be used for certain heart arrhythmias or neuropathic pain. It can be taken intravenously or by mouth. The intravenous form generally begins working within 30 minutes and is effective for roughly 24 hours. Blood levels can be measured to determine the proper dose. Common side effects include nausea, stomach pain, loss of appetite, poor coordination, increased hair growth, and enlargement of the gums. Potentially serious side effects include sleepiness, self harm, liver problems, bone marrow suppression, low blood pressure, and toxic epidermal necrolysis. There is evidence that use during pregnancy results in abnormalities ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lidocaine
Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia. When used for local anaesthesia or in nerve blocks, lidocaine typically begins working within several minutes and lasts for half an hour to three hours. Lidocaine mixtures may also be applied directly to the skin or mucous membranes to numb the area. It is often used mixed with a small amount of adrenaline (epinephrine) to prolong its local effects and to decrease bleeding. If injected intravenously, it may cause cerebral effects such as confusion, changes in vision, numbness, tingling, and vomiting. It can cause low blood pressure and an irregular heart rate. There are concerns that injecting it into a joint can cause problems with the cartilage. It appears to be generally safe for use in pregnancy. A lower dose may be required in those with liver problems. It is generally safe to use in those ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vagus Nerve
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right vagus nerves—but they are typically referred to collectively as a single subsystem. The vagus is the longest nerve of the autonomic nervous system in the human body and comprises both sensory and motor fibers. The sensory fibers originate from neurons of the nodose ganglion, whereas the motor fibers come from neurons of the dorsal motor nucleus of the vagus and the nucleus ambiguus. The vagus was also historically called the pneumogastric nerve. Structure Upon leaving the medulla oblongata between the olive and the inferior cerebellar peduncle, the vagus nerve extends through the jugular foramen, then passes into the carotid sheath between the internal carotid artery and the internal jugular vein down to the neck, chest, and abdom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
