When the day is hot chest tightness, shortness of breath and dyspnea, there are usually the following reasons: First, the factor of lack of oxygen, in the lack of oxygen will be consciously difficult to breathe, usually in the heat of the day when the body temperature rises, this will make shortness of breath. When the oxygen saturation in the blood is insufficient, the partial pressure of oxygen is low and the partial pressure of carbon dioxide is high, and the imbalance of the ventilation blood flow ratio will cause chest tightness and shortness of breath, accompanied by dyspnea. Secondly, if you feel that the above symptoms are aggravated when it is hot, there is usually a factor of inadequate blood supply to the heart, often due to insufficient blood supply to the coronary arteries. The above clinical symptoms may also occur in cases of coronary atherosclerotic heart disease and unstable angina pectoris, myocarditis, pericarditis, etc. Thirdly, the above clinical symptoms may also appear if the cerebral blood vessels dilate significantly during the heat.