Syncope, or fainting, is a sudden loss of consciousness which does not require any intervention to resolve. Michael H. Crawford, M.D., author of "Current Diagnosis and Treatment in Cardiology," says syncope is experienced by nearly 50 percent of adults during their lifetime. Neurocardiogenic syncope, specifically, is largely fainting that occurs due to a drop in blood pressure. As a result, blood circulation in the brain is diminished to the point that the person loses consciousness. There are three types of neurocardiogenic syncope that can cause complications: vasovagal, carotid sinus hypersensitivity and situational.
Complications of Vasovagal Syncope
Vasovagal syncope is the most common cause of fainting in young, healthy people and responsible for approximately 60 percent of all syncope cases, according to the Heart Rhythm Society. The causes of this form of neurocardiogenic syncope involve a low blood pressure reflex and low heart rate, referred to in medical terminology as vasodepressive and vasovagal responses, respectively. When a person experiences vasovagal syncope, he faints upon standing up from a lying position. Complications from vasovagal syncope include injury and in rare instances, death, from a faint-related fall. These complications arise more frequently after prolonged standing, fatigue, feelings of fear and during or after giving blood, explains Crawford. Vasogal syncope itself is benign and does not lead to any other complications aside from fainting.
Complications of Carotid Sinus Hypersensitivity
The carotid sinus is an important area along the carotid artery—the major artery supplying blood to the brain. Specialized receptors located on the carotid sinus help control blood pressure and heart rate. In susceptible individuals, particularly the elderly, pressure or stimulation of this area found on the side of the neck can cause a reflex by the receptors which lowers heart rate and blood pressure enough to induce fainting. Complications associated with carotid sinus hypersensitivity include injury and death from faint-related falls. No other complications arise from this form of neurocardiogenic syncope. This type of syncope is usually triggered by turning the head to the side, shaving the neck or wearing a tight collar, explains Crawford.
Complications of Situational Syncope
Situational causes of syncope include urination, defecation, coughing and swallowing. Similar to the other forms of neurocardiogenic syncope, situational syncope results from a heart rate and blood pressure lowering reflex; however, this form also involves a nervous system reflex from the internal abdominal area. Holding of the breath, referred to as the Valsalva maneuver, is common during situational acts such as coughing and defecation and is thought to cause the fainting reflex. This type of neurocardiogenic syncope is benign in and of itself with complications arising only from falls related to fainting. Crawford says situational syncope may be prevented by remembering to maintain a normal breathing pattern during the aforementioned situations.
References
- "Current Diagnosis and Treatment in Cardiology"; Syncope; Michael H. Crawford, M.D.; 2009
- Hearth Rhythm Society: Neurocardiogenic and Non-Cardiovascular Syncope
