Blackout, also known as blackout. It is a clinical condition in which the eyes are unable to see or make out objects when looking at them, and are characterized by darkness in front of the eyes. Clinical mostly in the form of transient blackout, often due to transient cerebral ischemia, anemia, hypotension, etc., should be noted! 1, blood rheology examination mainly manifested as whole blood viscosity, plasma viscosity, hematocrit, fibrinogen and platelet aggregation rate and other indicators are increased. 2, cerebrovascular examination, such as transcranial Doppler examination, carotid ultrasound, digital subtraction angiography, MRA examination. Cervical spine examination, such as cervical spine X-ray, cervical spine CT scan or cervical spine MRI examination, can be used. 4.Cranial CT scan or MRI examination Observe intracranial ischemia, except hemorrhagic disease. 5.Electrocardiogram Mainly to exclude the diagnosis. Whether the patient has atrial fibrillation, frequent premature beats, old myocardial infarction, left ventricular hypertrophy and so on. Echocardiography Check whether there are heart valve lesions, such as rheumatic valve disease, senile valve disease.