Accelerated heartbeat, chest tightness and breathlessness may be caused by the following diseases: 1, rapid arrhythmias, such as rapid atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia, atrial or ventricular tachycardia, etc. The accelerated heartbeat will lead to a decrease in the contractile function of the heart and a decrease in the ejection function of the heart, resulting in chest tightness and breathlessness; 2, the most common is ischemic cardiovascular diseases such as angina pectoris. The most common is ischemic cardiovascular diseases such as angina pectoris, when angina pectoris attacks, patients may experience chest pain and other discomfort, partly accompanied by an accelerated heartbeat and dyspnea; 3, the possibility of an acute attack of chronic heart failure, if the patient already has previous cardiac insufficiency, in the case of some triggers, such as intrapulmonary infection, strenuous exercise, increased blood pressure, etc., will trigger an acute attack of heart failure, which will also show an accelerated heartbeat, chest tightness, breathlessness; 4, there are also symptoms of chronic heart failure. 4. Some other patients have primary pulmonary diseases, such as tension pneumothorax, which also have similar symptoms.