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A premature ventricular contraction (PVC) — also known as a premature ventricular complex, ventricular premature contraction (or complex or complexes) (VPC), ventricular premature beat (VPB), or ventricular extrasystole (VES) — is a relatively common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node, the normal heartbeat initiator. The electrical events of the heart detected by the electrocardiogram (ECG) allow a PVC to be easily distinguished from a normal heart beat. Although a PVC can be a sign of decreased oxygenation to the heart muscle, often PVCs are benign and may even be found in otherwise healthy hearts.〔(What is a PVC )〕 A PVC may be perceived as a "skipped beat" or felt as palpitations in the chest. In a normal heartbeat, the ventricles contract after the atria have helped to fill them by contracting; in this way the ventricles can pump a maximized amount of blood both to the lungs and to the rest of the body. In a PVC, the ventricles contract first and before the atria have optimally filled the ventricles with blood, which means that circulation is inefficient. However, single beat PVC abnormal heart rhythms do not usually pose a danger and can be asymptomatic in healthy individuals. A PVC is a type of ectopic beat. ==Signs and symptoms== Although there are many signs and symptoms associated with PVCs, PVCs may have no symptoms at all. An isolated PVC is hard to catch without the use of a Holter monitor. PVCs may be perceived as a skipped heart beat, a strong beat, or a feeling of suction in the chest. They may also cause chest pain, a faint feeling, fatigue, or hyperventilation after exercise.〔 Several PVCs in a row becomes a form of ventricular tachycardia (VT), which is a potentially fatal abnormal heart rhythm. Some other possible signs and symptoms of PVCs: * Abnormal ECG * Irregular heart beat * Shortness of breath * Dizziness * Feeling your heart beat (palpitations) * Feeling of occasional, forceful beats * Increased awareness of your heart beat 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「premature ventricular contraction」の詳細全文を読む スポンサード リンク
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