If fainting spells occur often without a triggering event, syncope may be a sign of an underlying heart disease. In the case where syncope is caused by cardiac disease, the treatment is much more sophisticated than that of vasovagal syncope and may involve pacemakers and implantable cardioverter-defibrillators depending on the precise cardiac cause. Risk tools
The San Francisco syncope rule was developed to isolate people who have higher risk for a serious cause of syncope. High risk is anyone who has: congestive heart failure, hematocrit <30%, electrocardiograph abnormality, shortness of breath, or systolic blood pressure <90 mmHg. The San Francisco syncope rule however was not validated by subsequent studies.The Canadian syncope risk score was developed to help select low-risk people that may be viable for discharge home. A score of <0 on the Canadian syncope risk score is associated with <2% risk of serious adverse event within 30 days. It has been shown to be more effective than older syncope risk scores even combined with cardiac biomarkers at predicting adverse events. Epidemiology
There are 18.1–39.7 syncope episodes per 1000 people in the general population. Rates are highest between the ages of 10–30 years old. This is likely because of the high rates of vasovagal syncope in the young adult population. Older adults are more likely to have orthostatic or cardiac syncope. Syncope affects about three to six out of every thousand people each year. It is more common in older people and females. It is the reason for 2–5% of visits to emergency departments and admissions to hospital.
It is often possible to manage these symptoms with specific behavioral techniques. Another evolutionary psychology view is that some forms of fainting are non-verbal signals that developed in response to increased inter-group aggression during the paleolithic. A non-combatant who has fainted signals that she or he is not a threat. This would explain the association between fainting and stimuli such as bloodletting and injuries seen in blood-injection-injury type phobias such as needle phobia as well as the gender differences.Much of this pathway was discovered in animal experiments by Bezold (Vienna) in the 1860s. In animals, it may represent a defence mechanism when confronted by danger ("playing possum"). Situational syncope
Syncope may be caused by specific behaviors including coughing, urination, defecation, vomiting, swallowing (deglutition), and following exercise. Manisty et al. note: "Deglutition syncope is characterised by loss of consciousness on swallowing; it has been associated not only with ingestion of solid food, but also with carbonated and ice-cold beverages, and even belching." Fainting can occur in "cough syncope" following severe fits of coughing, such as that associated with pertussis or "whooping cough." Neurally mediated syncope may also occur when an area in the neck known as the carotid sinus is pressed. A normal response to carotid sinus massage is reduction in blood pressure and slowing of the heart rate. Especially in people with hypersensitive carotid sinus syndrome this response can cause syncope or presyncope.