”Three volts” during the Qinhuangdao high temperature and humidity, outdoor as “sauna” days, sweltering heat, in addition to the prevention of heat stroke, coronary heart patients should be particularly vigilant about the occurrence of myocardial infarction. Many patients with a history of cardiovascular disease recently returned to the hospital to “report”, the rate of recurrence of old diseases rose significantly, myocardial infarction patients than 20% to 30% higher than before the three volts. Acute myocardial infarction is based on the rupture of atherosclerotic plaque in the coronary arteries, resulting in acute occlusion of the coronary arteries due to thrombosis, causing ischemic necrosis of the myocardium. If resuscitation is not done properly, it may lead to sudden cardiac death. Many people know that the cold winter is the high incidence of cardiovascular disease, but I do not know that in the weather of high temperature and low air pressure, especially the “wet and stuffy” sauna days, when the air humidity increases, the oxygen content decreases, people who usually suffer from hypertension, coronary heart disease often feel discomfort, chest tightness, shortness of breath, dizziness and other symptoms. There is a clear relationship between the occurrence of cardiovascular diseases and the temperature. When the ambient temperature exceeds 35℃, the metabolism of human body will be accelerated, the subcutaneous blood vessels will be dilated, the blood flow to the skin will be significantly increased, and the blood flow back to the heart will also be significantly increased. And at the same time the human sympathetic nerve tone increased, heart rate accelerated, will greatly increase the workload of the heart. In addition, high temperature and high humidity weather, a lot of sweating will also lead to water loss, blood viscosity increases, so the risk of platelet aggregation and thrombosis increases, coupled with the coronary arteries of coronary heart patients already have a lesion basis, the above factors will significantly increase the probability of acute myocardial infarction. In order for coronary heart disease patients to survive the summer, reasonable medication, strict control of blood pressure, blood lipids and blood sugar is still the key. The usual life should be a light diet, low salt, and a moderate amount of activity. For cardiovascular patients, summer exercise should be done in the morning and evening, mainly walking, jogging and tai chi, avoiding high temperature periods and strenuous exercise. Once angina occurs, patients with coronary artery disease often take nitroglycerin under the tongue at home to relieve symptoms, rather than go to the doctor. However, there are four cases where angina should be seen immediately without a minute’s delay. In one case, the patient “persisted” at home for 1 day before coming to the doctor because he was worried about stenting, and by then he had already become a complete atrioventricular block, missing the best golden opportunity for resuscitation. A temporary pacemaker had to be implanted for treatment. 1, new onset angina: new onset angina within one month, induced by a lighter load. 2, worsening angina: angina has occurred before, but this time the frequency of pain episodes increased, the degree of aggravation, prolonged time frame, changes in the triggering factors, nitric acid drugs are difficult to relieve, then need to seek medical attention, because it means that has changed from stable angina to unstable angina. 3, resting angina and nocturnal angina: Previously, angina appeared during exertion, temper tantrums, emotional stress, but this time it is in a quiet state or at night when sleeping. 4, post-infarction angina: Previously had a myocardial infarction, regular drug treatment, and angina occurred again. In short, on the basis of previous stable angina, more frequent attacks, more easily induced, heavier symptoms, longer duration, nitroglycerin is not easy to relieve, etc. should promptly call 120 emergency or go directly to the hospital. Of course, patients who have never had angina but have atypical symptoms such as toothache, arm pain, back pain, abdominal pain, etc. should also seek medical attention promptly to rule out the occurrence of myocardial infarction.