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Palpitation is a perceived abnormality of the heartbeat characterized by awareness of heart muscle contractions in the chest: hard beats, fast beats, irregular beats, and/or pauses. They are both a symptom reported by the patient and a medical diagnosis. Palpitation is frequently associated with anxiety, and do not necessarily indicate a structural or functional abnormality of the heart, but they can be a symptom arising from an objectively rapid or irregular heartbeat. Palpitation can be intermittent and of variable frequency and duration, or continuous. Associated symptoms include dizziness, shortness of breath, sweating, headaches, and chest pain. Palpitation may be associated with coronary heart disease, hyperthyroidism, diseases affecting cardiac muscle such as hypertrophic cardiomyopathy, diseases causing low blood oxygen such as asthma and emphysema; kidney disease; low levels of brain Serotonin;〔{The Edge Effect, by Eric R. Braverman, M.D., 2004, pp. 142〕 blood loss, and pain; drugs such as antidepressants, alcohol, nicotine, caffeine, cocaine, and amphetamines; electrolyte imbalances of magnesium, potassium and calcium; and deficiencies of nutrients such as taurine, arginine, and iron. ==Signs and symptoms== Three common descriptions of ''palpitation'' are “flip-flopping” (or “stop and start”), often caused by premature contraction of the atrium or ventricle, with the perceived “stop” from the pause following the contraction, and the “start” from the subsequent forceful contraction; rapid “fluttering in the chest,” with regular “fluttering” suggesting supraventricular or ventricular arrhythmias (including sinus tachycardia) and irregular “fluttering” suggesting atrial fibrillation, atrial flutter, or tachycardia with variable block; and “pounding in the neck” or neck pulsations, often due to “cannon” A waves in the jugular venous pulsations that occur when the right atrium contracts against a closed tricuspid valve. Palpitation associated with chest pain suggests ischemic heart disease, or if the chest pain is relieved by leaning forward, pericardial disease is suspected. Palpitation associated with light-headedness, fainting or near fainting suggest low blood pressure and may signify a life-threatening abnormal heart rhythm. Palpitation that occurs regularly with exertion suggests a rate-dependent bypass tract or hypertrophic cardiomyopathy. If a benign cause for these concerning symptoms cannot be found at the initial visit, then ambulatory monitoring or prolonged heart monitoring in the hospital might be warranted. Noncardiac symptoms should also be elicited since the palpitations may be caused by a normal heart responding to a metabolic or inflammatory condition. Weight loss suggests hyperthyroidism. Palpitation can be precipitated by vomiting or diarrhea that leads to electrolyte disorders and hypovolemia. Hyperventilation, hand tingling, and nervousness are common when anxiety or panic disorder is the cause of the palpitations. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Palpitations」の詳細全文を読む スポンサード リンク
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