Abstract and Vasovagal Syncope
A sudden transient loss of consciousness and postural tone, syncope may result from cardiovascular or noncardiovascular causes or a combination of the two. The act of "fainting" or "passing out" usually is caused by decreased cerebral blood flow that may be secondary to decreased cardiac output or hypotension; arrhythmias, including conduction abnormalities, also can cause syncope, particularly in the young. The most common physiological manifestation observed during syncope in younger patients is a combination of peripheral arterial and venous vasodilation followed by relative bradycardia. Vasovagal syncope (VVS) usually occurs during orthostatic stress when the patient experiences not only a pooling of 500–700 ml of blood in dependent vessels, but also a progressive loss of a similar volume of plasma through dependent capillaries caused by the increased hydrostatic pressure.
The term "vasovagal" syncope first appeared in 1907, when it was used to describe a collection of vagal symptoms, including epigastric, respiratory, and cardiac discomfort that occurs in association with vasomotor spasm. Twenty-five years later, the definition was refined to include a decrease in blood pressure associated with a slowing of the ventricular rate.
Syncope is most common in the young and the old, with an incidence peak at around 15 years of age, particularly in women; subsequently, there is a progressive increase in frequency over the age of 45 years followed by a sharp rise beginning at about 70 years (Figure 1).
Frequency of Fainting as Reason for Doctor's Visit
In a broad population sample, Framingham Heart Study investigators reported evaluating 7,814 free-living participants, 822 (10.5%) of which reported at least one syncopal event during an average of 17 years. The incidence of a first report of syncope was 6.2 per 1000 person-years. Assuming a constant incidence rate over time, the authors calculated a 10-year cumulative incidence of syncope of 6%; which means a 42% prevalence of syncope during the life of people living 70 years. However, given that the incidence was not constant, the rate of syncope was 11 per 1000 person-years for both men and women in their 70s and 17 (for men) and 19 (for women) per 1000 person-years after the age of 80.
Among Framingham participants with syncope, VVS was diagnosed in 21.2% of participants versus cardiac syncope (9.5%) and orthostatic syncope (9.4%); in 36.6% of patients, the cause of syncope was unknown. In those patients with VVS, the presence of cardiovascular disease contributed to higher rates of occurrence in women versus men (14.0% vs. 11.2%). In this study, VVS was not associated with any increased risk of cardiovascular mortality or morbidity.
Similar findings were reported in a retrospective study of 641 patients in whom nonautonomic causes of syncope had been excluded (i.e., neurologic, cardiologic, and metabolic causes), screening via clinical features and autonomic testing found that 227, or 35%, of patients had vasovagal syncope.
While not limited to the young, VVS is the most common form of syncope in younger individuals: Two surveys of the frequency of syncope in medical students demonstrated that 20-25% of males and 40-50% of females reported to have experienced at least one such episode.[7,8] The lifetime cumulative incidence in young females has been reported to be about twice as high as in males. Fortunately, when syncope occurs early in life, the symptoms tend to run a benign course and diminish with maturity.
Various circumstances are triggers for VVS including prolonged standing, especially when combined with warm temperatures, confined spaces, and/or crowding; emotional situations especially those of sudden onset; pain; fasting; lack of sleep or fatigue; menstruation; illness with fever; micturition; coughing or stretching; standing quickly; and hyperventilation. Rapid weight loss and various medications and substances, including alcohol (although syncope must be distinguished from intoxication) also can be triggers. Patients may experience prodromal signs and symptoms prior to a syncopal episode; although usually more forceful in the young, prodromes may be reported by some elderly subjects, too.
Although usually not associated with increased risks of major adverse outcomes, VVS can require extensive testing and possible hospital admission. Furthermore, morbidity from fainting is a risk and includes lacerations and contusions, limb fractures, or worse if the syncope occurs while driving.[10,11] In one study, about one-third of syncope patients experienced some trauma due to a syncopal event. More than just a medical issue, recurrent syncope may lead to job loss, such as jobs requiring a lot of driving or work that leaves people at greater risk from a loss of consciousness, such as construction. Even without such severe consequences, recurrent VVS may have a negative impact on a person's quality of life.
In the last few years, a large amount of data has been published regarding the epidemiology, diagnosis, and management of syncope. In 2006, an AHA/ACCF scientific statement was published specifically detailing the evaluation of syncope. As investigators have determined a much larger incidence of VVS in the elderly than previously appreciated, there has been a need for a review of the available data distinguishing the differences between VVS in younger and older populations.
In this summary, Maw Pin Tan, BMEDSCI, BMBS, MRCP, and Steve W. Parry, MBBS, PHD, FRCP, review their state-of-the-art paper on VVS in the older patient as published in the Journal of the American College of Cardiology.
Cardiosource © 2008 American College of Cardiology
© 2006 American College of Cardiology
Cite this: Vasovagal Syncope in the Older Patient - Medscape - May 28, 2008.