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Inappropriate Sinus Tachycardia (IST) is a rare type of cardiac arrhythmia, within the category of supraventricular tachycardia (SVT). IST may be caused by the sinus node itself having an abnormal structure or function, or it may be part of a problem called dysautonomia, a disturbance and/or failure of the autonomic nervous system. Research into the mechanism and etiology (cause) of Inappropriate Sinus Tachycardia is ongoing. IST is viewed by most to be a benign condition in the long-term. Symptoms of IST however, may be distracting and warrant treatment. The heart is a strong muscle and typically can sustain the higher-than-normal heart rhythm, though monitoring the condition is generally recommended.〔http://www.ncbi.nlm.nih.gov/pubmed/23265330〕 The mechanism and primary etiology of Inappropriate Sinus Tachycardia has not been fully elucidated. An autoimmune mechanism has been suggested as several studies have detected autoantibodies that activate beta adrenoreceptors in a portion of patients. The mechanism of the arrhythmia primarily involves the sinus node and peri-nodal tissue and does not require the AV node for maintenance. Treatments in the form of pharmacological therapy or catheter ablation are available, although it is currently difficult to treat successfully. == Symptoms == Symptoms reported by patients vary in frequency and severity. Symptoms associated with IST include: * Frequent or sustained palpitations() * Dyspnea (shortness of breath) and palpitations on exertion * Pre-syncope (feeling as if about to faint) * Fatigue (physical) * Dizziness * Exercise intolerance * Occasional paresthesia and cramping * Symptoms associated with autonomic nervous system disturbance, including GI disturbance inappropriate v-tach 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「Inappropriate sinus tachycardia」の詳細全文を読む スポンサード リンク
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