The sudden onset of rapid heartbeat and weakness should be considered if the patient has paroxysmal refractory supraventricular tachycardia, which generally conforms to the symptoms of sudden onset and stop. When supraventricular tachycardia occurs, because the heart rate is too fast, sometimes there is ineffective ejection of blood, and symptoms of peripheral discomfort or weakness occur. Similarly, when a patient has rapid atrial fibrillation, it can also lead to a feeling of weakness, and the pulse rate of atrial fibrillation is lower than the ventricular rate, and there is a very irregular rhythm of the heart rate, and when ventricular tachycardia occurs, there may also be a feeling of weakness.