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Sick Sinus Syndrome
Sinus node dysfunction (SND), also known as sick sinus syndrome (SSS), is a group of abnormal heart rhythms (arrhythmias) usually caused by a malfunction of the sinus node, the heart's primary pacemaker. Tachycardia-bradycardia syndrome is a variant of sick sinus syndrome in which the arrhythmia alternates between fast and slow heart rates. Signs and symptoms Often sinus node dysfunction produces no symptoms, especially early in the disease course. Signs and symptoms usually appear in more advanced disease and more than 50% of patients will present with syncope or transient near-fainting spells as well as bradycardias that are accompanied by rapid heart rhythms, referred to as tachycardia-bradycardia syndrome Other presenting signs or symptoms can include confusion, fatigue, palpitations, chest pain, shortness of breath, headache, and nausea. Patients can also present with symptoms of congestive heart failure, stroke or transient ischemic attacks due to the abnormal rhythm. Com ...
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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, either because the heart's natural cardiac pacemaker provides an inadequate or irregular heartbeat, or because there is a 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 pacemakers are on demand, in which the stimulation of the heart is based on the dynamic demand of the circulatory system. Others send out a fixed rate of impulses. A specific type of pacemaker, called an implantable cardioverter-defibrillator, combines pacemaker and ...
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Sinus Arrest
Sinoatrial arrest is a medical condition wherein the sinoatrial node of the heart transiently ceases to generate the electrical impulses that normally stimulate the myocardium, myocardial tissues to contract and thus the heart to beat. It is defined as lasting from 2.0 seconds to several minutes. Since the heart contains multiple pacemakers, this interruption of the cardiac cycle generally lasts only a few seconds before another part of the heart, such as the atrio-ventricular junction or the Ventricle (heart), ventricles, begins pacing and restores the heart action. This condition can be detected on an electrocardiogram (ECG) as a brief period of irregular length with no electrical activity before either the sinoatrial node resumes normal pacing, or another pacemaker begins pacing. If a pacemaker other than the sinoatrial node is pacing the heart, this condition is known as an escape rhythm. If no other pacemaker begins pacing during an episode of sinus arrest it becomes a card ...
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Beta Blocker
Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms ( arrhythmia), and to protect the heart from a second heart attack after a first heart attack ( secondary prevention). They are also widely used to treat high blood pressure, although they are no longer the first choice for initial treatment of most people. Beta blockers are competitive antagonists that block the receptor sites for the endogenous catecholamines epinephrine (adrenaline) and norepinephrine (noradrenaline) on adrenergic beta receptors, of the sympathetic nervous system, which mediates the fight-or-flight response. Beta-adrenergic receptors are found on cells of the heart muscles, smooth muscles, airways, arteries, kidneys, and other tissues that are part of the sympathetic nervous system and lead to stress responses, especially when they are stimulated by epinephrine (adrenaline). Beta blockers interfere with the binding to th ...
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SCN5A
Sodium channel protein type 5 subunit alpha, also known as NaV1.5 is an integral membrane protein and tetrodotoxin-resistant voltage-gated sodium channel subunit. NaV1.5 is found primarily in cardiac muscle, where it mediates the fast influx of Na+-ions (INa) across the cell membrane, resulting in the fast depolarization phase of the cardiac action potential. As such, it plays a major role in impulse propagation through the heart. A vast number of cardiac diseases is associated with mutations in NaV1.5 (see paragraph genetics). ''SCN5A'' is the gene that encodes the cardiac sodium channel NaV1.5. Gene structure SCN5A is a highly conserved gene located on human chromosome 3, where it spans more than 100 kb. The gene consists of 28 exons, of which exon 1 and in part exon 2 form the 5' untranslated region ( 5’UTR) and exon 28 the 3' untranslated region ( 3’UTR) of the RNA. SCN5A is part of a family of 10 genes that encode different types of sodium channels, i.e. brain-type ( ...
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Lyme Disease
Lyme disease, also known as Lyme borreliosis, is a tick-borne disease caused by species of ''Borrelia'' bacteria, Disease vector, transmitted by blood-feeding ticks in the genus ''Ixodes''. It is the most common disease spread by ticks in the Northern Hemisphere. Infections are most common in the spring and early summer. The most common sign of infection is an expanding red rash, known as erythema migrans (EM), which appears at the site of the tick bite about a week afterwards. The rash is typically neither itchy nor painful. Approximately 70–80% of infected people develop a rash. Other early symptoms may include fever, headaches and fatigue (medical), tiredness. If untreated, symptoms may include Facial nerve paralysis, loss of the ability to move one or both sides of the face, arthritis, joint pains, Meningitis, severe headaches with neck stiffness or heart palpitations. Months to years later, repeated episodes of joint pain and swelling may occur. Occasionally, shootin ...
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Chagas Disease
Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily Triatominae, known as "kissing bugs". The symptoms change throughout the infection. In the early stage, symptoms are typically either not present or mild and may include fever, swollen lymph nodes, headaches, or swelling at the site of the bite. After four to eight weeks, untreated individuals enter the chronic phase of disease, which in most cases does not result in further symptoms. Up to 45% of people with chronic infections develop heart disease 10–30 years after the initial illness, which can lead to heart failure. Digestive complications, including an enlarged esophagus or an enlarged colon, may also occur in up to 21% of people, and up to 10% of people may experience nerve damage. is commonly spread to humans and other mammals by the kissing bug's bite wound and the bug's infected feces. The disea ...
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Rheumatic Fever
Rheumatic fever (RF) is an inflammation#Disorders, inflammatory disease that can involve the heart, joints, skin, and brain. The disease typically develops two to four weeks after a Streptococcal pharyngitis, streptococcal throat infection. Signs and symptoms include fever, multiple arthralgia, painful joints, chorea, involuntary muscle movements, and occasionally a characteristic non-itchy rash known as erythema marginatum. The heart is involved in about half of the cases. Damage to the heart valves, known as valvular heart disease#Inflammatory disorders, rheumatic heart disease (RHD), usually occurs after repeated attacks but can sometimes occur after one. The damaged valves may result in heart failure, atrial fibrillation and infective endocarditis, infection of the valves. Rheumatic fever may occur following an infection of the throat by the bacterium ''Streptococcus pyogenes''. If the infection is left untreated, rheumatic fever occurs in up to three percent of people. Th ...
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Connective Tissue Disease
Connective tissue diseases (also termed connective tissue disorders, or collagen vascular diseases), are medical conditions that affect connective tissue. Connective tissues protect, support, and provide structure for the body's other tissues and structures. They hold the body's structures together. Connective tissues consist of two distinct proteins: elastin and collagen. Tendons, ligaments, skin, cartilage, bone, and blood vessels are all made of collagen. Skin and ligaments also contain elastin. These proteins and the surrounding tissues may suffer damage when the connective tissues become inflamed. The two main categories of connective tissue diseases are (1) a set of relatively rare genetic disorders affecting the primary structure of connective tissue, and (2) a variety of acquired diseases where the connective tissues are the site of multiple, more or less distinct immunological and inflammatory reactions. Diseases in which inflammation or weakness of collagen tends to ...
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Hereditary Haemochromatosis
Hereditary haemochromatosis type 1 (HFE-related haemochromatosis) is a genetic disorder characterized by excessive intestinal absorption of Human iron metabolism, dietary iron, resulting in a pathological increase in total body iron stores. Humans, like most animals, have no mechanism to regulate excess iron, simply losing a limited amount through various means like sweating or menstruating. Excess iron accumulates in tissues and organs, disrupting their normal function. The most susceptible organs include the liver, heart, pancreas, skin, joints, gonads, thyroid and pituitary gland; patients can present with cirrhosis, polyarthropathy, hypogonadism, heart failure, or diabetes. There are five types of hereditary hemochromatosis: type 1, Juvenile hemochromatosis, 2 (2A, 2B), Haemochromatosis type 3, 3, Haemochromatosis type 4, 4 and 5, all caused by mutated genes. Hereditary hemochromatosis type 1 is the most frequent, and uniquely related to the HFE gene. It is most common among ...
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Amyloidosis
Amyloidosis is a group of diseases in which abnormal proteins, known as amyloid fibrils, build up in tissue. There are several non-specific and vague signs and symptoms associated with amyloidosis. These include fatigue, peripheral edema, weight loss, shortness of breath, palpitations, and Orthostatic hypotension, feeling faint with standing. In AL amyloidosis, specific indicators can include enlargement of the tongue and periorbital purpura. In wild-type ATTR amyloidosis, non-cardiac symptoms include: bilateral carpal tunnel syndrome, lumbar spinal stenosis, biceps tendon rupture, Small fiber peripheral neuropathy, small fiber neuropathy, and autonomic dysfunction. There are about 36 different types of amyloidosis, each due to a specific Proteopathy, protein misfolding. Within these 36 proteins, 19 are grouped into Organ-limited amyloidosis, localized forms, 14 are grouped as Systemic disease, systemic forms, and three proteins can identify as either. These proteins can become ...
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Sarcoidosis
Sarcoidosis (; also known as Besnier–Boeck–Schaumann disease) is a disease involving abnormal collections of White blood cell, inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly affected are the eyes, liver, heart, and Human brain, brain, though any Organ (anatomy), organ can be affected. The signs and symptoms depend on the organ involved. Often, no symptoms or only mild symptoms are seen. When it affects the lungs, wheezing, coughing, shortness of breath, or chest pain may occur. Some may have Löfgren syndrome with fever, Bilateral hilar lymphadenopathy, enlarged hilar lymph nodes, arthritis, and a rash known as erythema nodosum. The cause of sarcoidosis is unknown. Some believe it may be due to an immune reaction to a trigger such as an infection or chemicals in those who are genetically predisposed. Those with affected family members are at greater risk. Diagnosis is partly based on signs ...
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Heart Failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to Cardiac cycle, fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF typically presents with shortness of breath, Fatigue (medical), excessive fatigue, and bilateral peripheral edema, leg swelling. The severity of the heart failure is mainly decided based on ejection fraction and also measured by the severity of symptoms. Other conditions that have symptoms similar to heart failure include obesity, kidney failure, liver disease, anemia, and thyroid disease. Common causes of heart failure include coronary artery disease, heart attack, hypertension, high blood pressure, atrial fibrillation, valvular heart disease, alcohol use disorder, excessive alcohol consumption, infection, and cardiomyopathy. These cause heart failure by altering the structure or the function of the heart or in some cases both. There are ...
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