If a patient suddenly develops a rapid heartbeat, it is possible that the patient is experiencing paroxysmal atrial fibrillation or atrial flutter, or paroxysmal supraventricular tachycardia. It is best to have an electrocardiogram to help clarify what type of arrhythmia is occurring. The treatment options may vary from arrhythmia to arrhythmia. In the case of atrial fibrillation, it is recommended that the patient be treated aggressively to restore sinus rhythm, such as amiodarone by sedation and subcutaneous injection of low molecular heparin. In the case of simple sinus tachycardia, patients are advised to take oral bisoprolol or metoprolol to slow down the heart rate and also to further identify the cause of this sudden increase in heart rate. It is more common to find out the cause of the sudden rapid heartbeat due to the disturbance of the regulation of the vegetative nerve function, or the patient may have acute myocardial ischemia.