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Romano–Ward Syndrome
Romano–Ward syndrome is the most common form of congenital long QT syndrome (LQTS), a genetic heart condition that affects the electrical properties of heart muscle cells. Those affected are at risk of abnormal heart rhythms which can lead to fainting, seizures, or sudden death. Romano–Ward syndrome can be distinguished clinically from other forms of inherited LQTS as it affects only the electrical properties of the heart, while other forms of LQTS can also affect other parts of the body. Romano–Ward syndrome is caused by abnormal variants in the genes responsible for producing certain proteins used to transport charged particles (ion channels) within the heart. These abnormalities interfere with the electrical signals that heart cells use to coordinate contractions, causing the heart to take longer to recharge in between beats. The condition is usually diagnosed using an electrocardiogram, but other tests sometimes used include Holter monitoring, exercise testing, and g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinus Rhythm
A sinus rhythm is any cardiac rhythm in which depolarisation of the cardiac muscle begins at the sinus node. It is necessary, but not sufficient, for normal electrical activity within the heart. On the electrocardiogram (ECG), a sinus rhythm is characterised by the presence of P waves that are normal in morphology. The term normal sinus rhythm (NSR) is sometimes used to denote a specific type of sinus rhythm where all other measurements on the ECG also fall within designated normal limits, giving rise to the characteristic appearance of the ECG when the electrical conduction system of the heart is functioning normally; however, other sinus rhythms can be entirely normal in particular patient groups and clinical contexts, so the term is sometimes considered a misnomer and its use is sometimes discouraged. Other types of sinus rhythm that can be normal include sinus tachycardia, sinus bradycardia, and sinus arrhythmia. Sinus rhythms may be present together with various othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torsades De Pointes
''Torsades de pointes, torsade de pointes'' or ''torsades des pointes'' (TdP; also called ''torsades'') (, , translated as "twisting of peaks") is a specific type of abnormal heart rhythm that can lead to sudden cardiac death. It is a polymorphic ventricular tachycardia that exhibits distinct characteristics on the electrocardiogram (ECG). It was described by French physician François Dessertenne in 1966. Prolongation of the QT interval can increase a person's risk of developing this abnormal heart rhythm, occurring in between 1% and 10% of patients who receive QT-prolonging antiarrhythmic drugs. Signs and symptoms Most episodes will revert spontaneously to a normal sinus rhythm. Symptoms and consequences include palpitations, dizziness, lightheadedness (during shorter episodes), fainting (during longer episodes), and sudden cardiac death. Causes Torsades occurs as both an inherited (linked to at least 17 genes) and as an acquired form caused most often by drugs a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KvLQT1
Kv7.1 (KvLQT1) is a potassium ion channel, channel protein whose primary subunit in humans is encoded by the ''KCNQ1'' gene. Its mutation causes Long QT syndrome, Kv7.1 is a voltage and Lipid-gated ion channels, lipid-gated potassium channel present in the cell membranes of cardiac tissue and in inner ear neurons among other tissues. In the cardiac cell (biology), cells, Kv7.1 mediates the IKs (or slow delayed rectifying K+) current that contributes to the repolarization of the cell, terminating the cardiac action potential and thereby the heart's Muscle contraction, contraction. It is a member of the KCNQ channels, KCNQ family of potassium channels. Structure KvLQT1 is made of six membrane-spanning domains S1-S6, two intracellular domains, and a pore loop. The KvLQT1 channel is made of four KCNQ1 subunits, which form the actual ion channel. Function This gene encodes a protein for a voltage-gated potassium channel required for the repolarization phase of the cardiac ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 11
Chromosome 11 is one of the 23 pairs of chromosomes in humans. Humans normally have two copies of this chromosome. Chromosome 11 spans about 135 million base pairs (the building material of DNA) and represents between 4 and 4.5 percent of the total DNA in cells. The shorter arm (p arm) is termed 11p while the longer arm (q arm) is 11q. At about 21.5 genes per megabase, chromosome 11 is one of the most gene-rich, and disease-rich, chromosomes in the human genome. More than 40% of the 856 olfactory receptor genes in the human genome are located in 28 single-gene and multi-gene clusters along the chromosome. Gene Number of genes The following are some of the gene count estimates of human chromosome 11. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project ( CCDS) takes an extremely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypokalemia
Hypokalemia is a low level of potassium (K+) in the blood serum. Mild low potassium does not typically cause symptoms. Symptoms may include feeling tired, leg cramps, weakness, and constipation. Low potassium also increases the risk of an abnormal heart rhythm, which is often too slow and can cause cardiac arrest. Causes of hypokalemia include vomiting, diarrhea, medications like furosemide and steroids, dialysis, diabetes insipidus, hyperaldosteronism, hypomagnesemia, and not enough intake in the diet. Normal potassium levels in humans are between 3.5 and 5.0 mmol/L (3.5 and 5.0 mEq/L) with levels below 3.5 mmol/L defined as hypokalemia. It is classified as severe when levels are less than 2.5 mmol/L. Low levels may also be suspected based on an electrocardiogram (ECG). The opposite state is called hyperkalemia that means high level of potassium in the blood serum. The speed at which potassium should be replaced depends on whether or not there are symptom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drug-induced QT Prolongation
A drug is any chemical substance other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect. Consumption of drugs can be via inhalation, injection, smoking, ingestion, absorption via a patch on the skin, suppository, or dissolution under the tongue. In pharmacology, a drug is a chemical substance, typically of known structure, which, when administered to a living organism, produces a biological effect. A pharmaceutical drug, also called a medication or medicine, is a chemical substance used to treat, cure, prevent, or diagnose a disease or to promote well-being. Traditionally drugs were obtained through extraction from medicinal plants, but more recently also by organic synthesis. Pharmaceutical drugs may be used for a limited duration, or on a regular basis for chronic disorders. Classification Pharmaceutical drugs are often classified into drug classes—groups of related drugs that have s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timothy Syndrome
Timothy syndrome is a rare autosomal dominant, autosomal-dominant disorder characterized by physical malformations, as well as neurological and developmental defects, including heart LQTS, QT-prolongation, heart arrhythmias, structural heart defects, syndactyly (webbing of fingers and toes), and autism spectrum disorders. Timothy syndrome represents one clinical manifestation of a range of disorders associated with mutations in Cav1.2, ''CACNA1C'', the gene encoding the calcium channel Cav1.2 α subunit. Signs and symptoms The most striking sign of Timothy syndrome type 1 is the co-occurrence of both syndactyly (about 0.03% of births) and long QT syndrome (1% per year) in a single patient. Other common symptoms include cardiac Heart arrhythmia, arrhythmia (94%), heart malformations (59%), and autism or an autism spectrum disorder (80% who survive long enough for evaluation). Facial dysmorphologies such as flattened noses also occur in about half of patients. Children with this diso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andersen–Tawil Syndrome
Andersen–Tawil syndrome, also called Andersen syndrome and long QT syndrome 7, is a rare genetic disorder affecting several parts of the body. The three predominant features of Andersen–Tawil syndrome include disturbances of the electrical function of the heart characterised by an abnormality seen on an Electrocardiography, electrocardiogram (a long QT interval) and a tendency to Heart arrhythmia, abnormal heart rhythms, physical characteristics including low-set ears and a Micrognathism, small lower jaw, and intermittent periods of muscle weakness known as Hypokalemic periodic paralysis, hypokalaemic periodic paralysis. Andersen–Tawil syndrome is inherited in an autosomal dominant pattern. It is caused in most cases by a mutation in the Kir2.1, ''KCNJ2'' gene which encodes an ion channel that transports potassium out of cardiac muscle cells. The arrhythmias seen in the condition can be treated with flecainide or Beta blocker, beta-blockers, but an Implantable cardioverter- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jervell And Lange-Nielsen Syndrome
Jervell and Lange-Nielsen syndrome (JLNS) is a rare type of long QT syndrome associated with severe, bilateral sensorineural hearing loss. Those with JLNS are at risk of abnormal heart rhythms called arrhythmias, which can lead to fainting, seizures, or sudden death. JLNS, like other forms of long QT syndrome, causes the cardiac muscle to take longer than usual to recharge between beats. It is caused by genetic variants responsible for producing ion channels that carry transport potassium out of cells. The condition is usually diagnosed using an electrocardiogram, but genetic testing can also be used. Treatment includes lifestyle measures, beta blockers, and implantation of a defibrillator in some cases. It was first described by Anton Jervell and Fred Lange-Nielsen in 1957. Symptoms and signs Jervell and Lange-Nielsen syndrome causes severe sensorineural hearing loss from birth, affecting both ears. Those affected have a prolonged QT interval on an electrocardiogram and are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hearing Loss
Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken language, and in adults it can create difficulties with social interaction and at work. Hearing loss can be temporary or permanent. Hearing loss related to age usually affects both ears and is due to cochlear hair cell loss. In some people, particularly older people, hearing loss can result in loneliness. Hearing loss may be caused by a number of factors, including: genetics, ageing, exposure to noise, some infections, birth complications, trauma to the ear, and certain medications or toxins. A common condition that results in hearing loss is chronic ear infections. Certain infections during pregnancy, such as cytomegalovirus, syphilis and rubella, may also cause hearing loss in the child. Hearing loss is diagnosed when hearing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palpitations
Palpitations occur when a person becomes aware of their heartbeat. The heartbeat may feel hard, fast, or uneven in their chest. Symptoms include a very fast or irregular heartbeat. Palpitations are a sensory symptom. They are often described as a skipped beat, a rapid flutter, or a pounding in the chest or neck. Palpitations are not always the result of a physical problem with the heart and can be linked to anxiety. However, they may signal a arrhythmia, fast or irregular heartbeat. Palpitations can be brief or long-lasting. They can be intermittent or continuous. Other symptoms can include dizziness, shortness of breath, sweating, headaches, and chest pain. There are a variety of causes of palpitations not limited to the following: Palpitation may be associated with coronary artery disease, coronary heart disease, perimenopause, hyperthyroidism, adult heart muscle diseases like hypertrophic cardiomyopathy, congenital heart diseases like atrial septal defects, diseases causing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atrial Fibrillation
Atrial fibrillation (AF, AFib or A-fib) is an Heart arrhythmia, abnormal heart rhythm (arrhythmia) characterized by fibrillation, rapid and irregular beating of the Atrium (heart), atrial chambers of the heart. It often begins as short periods of abnormal cardiac cycle, beating, which become longer or continuous over time. It may also start as other forms of arrhythmia such as atrial flutter that then transform into AF. Episodes can be asymptomatic. Symptomatic episodes may involve heart palpitations, syncope (medicine), fainting, Presyncope, lightheadedness, Unconsciousness, loss of consciousness, or shortness of breath. Atrial fibrillation is associated with an increased risk of heart failure, dementia, and stroke. It is a type of supraventricular tachycardia. Atrial fibrillation frequently results from bursts of tachycardia that originate in muscle bundles extending from the Atrium (heart), atrium to the pulmonary veins. Pulmonary vein isolation by catheter ablation, trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
