Premonitory syncope is a relatively common vasovagal syncope in young people and is very common. It often recurs, especially when under considerable emotional stress, extreme fatigue, pain, panic, or in crowded, hot rooms. Because the blood vessels in other parts of the body are not innervated by the vagus nerve except the heart, some scholars have recently suggested that the term neurocardiogenic syncope may be more appropriate. So, what causes syncope prognosis? The following is an introduction to syncope prognosis: In normal people in the upright tilt position, due to the decrease in the amount of return blood, the ventricular filling is insufficient, the effective beat volume is reduced, the inhibitory impulses from the arterial sinus and aortic arch pressure receptors to the vasomotor center are weakened, and the sympathetic tone is increased, causing the heart rate to accelerate and maintaining the blood pressure at a normal level. In patients with presyncope, such autonomic compensatory reflexes are inhibited and normal heart rate and blood pressure cannot be maintained. In combination with reduced ventricular volume in the upright tilt position, sympathetic tone increases, especially when accompanied by the positive inotropic effect of isoproterenol, causing a marked increase in contraction of the underfilled ventricle, at which point receptors in the posterior wall of the left ventricle are stimulated, vagal afferent fibers are activated, and impulses are transmitted to the center that This causes inhibition of the vasoconstrictor center and excitation of the diastolic center, resulting in bradycardia and/or lower blood pressure, which reduces cerebral blood flow and causes syncope. Patients with vasovagal syncope and elderly patients with hypertrophic cardiomyopathy both present with presyncope. Syncope with dizziness can also occur in patients with hypertrophic cardiomyopathy due to a decrease in blood pressure and when tachy or bradyarrhythmic arrhythmias occur.