What about sudden syncope? What are the specific causes of syncope?

? Syncope is a clinical symptom of sudden, reversible and transient loss of consciousness, which is caused by short-term large-scale cerebral ischemia and hypoxia. Often transient, the onset time of syncope is generally short, only a few seconds to a few minutes. Before losing consciousness, it is often accompanied by autonomic nervous dysfunction such as pallor, nausea, vomiting, dizziness and sweating. What are the specific causes of syncope?

? 1. Postural hypotension

? When a person lies down, the blood flow throughout the body is usually smooth. When they stand up, blood will concentrate on their feet because of gravity. At this time, under normal conditions, the blood vessels in their feet will contract, so that the blood flow in their legs can easily return to their hearts. People with autonomic nervous disorders are prone to faint because of the lack of this mechanism.

? 2. Postural hypotension syncope

? This syncope occurs in patients with defective or unstable vasoconstriction reflex. The decrease of blood pressure in upright position is mainly due to the increase of blood volume of lower limbs and the disappearance of vasoconstriction reflex. The main difference between this syncope and vasovagal syncope is that postural syncope is often induced by lying or sitting and suddenly standing up. Supine position test is helpful for the diagnosis of postural hypotension. For those suspected of postural hypotension, the upper arm blood pressure was measured by conventional sphygmomanometer in supine position and after standing for 3 minutes.

? 3. Cardiac hypertrophy

? Patients with myocardial hypertrophy can generally be observed by B-ultrasound of the heart. During the cardiac cycle, the ejection fraction decreases and the ventricular wall thickness increases. Therefore, the patient's syncope mainly occurred during exercise. If young people syncope during exercise, it is recommended to do ultrasound to rule out myocardial hypertrophy. Old people are different from young people. Generally, syncope in the elderly belongs to insufficient myocardial contractility or myocardial infarction. For middle-aged and elderly people with a history of atherosclerosis, it is necessary to check whether the heart function is normal.