课件：晕厥的诊断与治疗.ppt

* A yield is defined as information that will point to more finely focused tests, specialties, or treatments. Patient history and physical exam are the most productive diagnostic tools for recurrent syncope, accounting for 49-85% of all syncope diagnoses.1,2 An ECG, also considered a first-line test, is diagnostic in 2-11% of cases.2 Beyond that, other tests have variable diagnostic yields. Holter monitors (worn for 1-3 days) capture ECGs during a syncopal episode in only 1% of patients, based on a mean time to recurrent event of 5.1 months.7 The effectiveness of tilt table tests, a common tool used to identify vasovagal syncope, depends on several factors, including patient selection and use of provocative drugs. Depending on these factors, the rate of positive tests has been reported in the range of 11-87%.3,5 However, about 10% or more of the population (who do not experience syncope) will have positive tilt table tests.4,6 External loop recorders (worn for 2-3 weeks) are most productive in motivated patients who experience relatively frequent syncope. They provide a diagnostic yield of 20%.7 Electrophysiology (EP) studies are generally more productive in patients with structural heart disease (SHD) and therefore are generally a higher priority for patients in this group.1 EP studies are used to diagnose syncope by inducing symptoms under controlled conditions, thereby attaining a “presumptive” diagnosis.1 EP testing usually fails to identify intermittent bradycardia as a cause of syncope (6%) and may sometimes reveal unrelated rhythm disturbances that may be mistakenly identified as the cause of syncope.2 1. Kapoor W, et al. A prospective evaluation and follow-up of patients with syncope. N Engl J Med 1983;309:197-204. 2. Kapoor W. Diagnostic evaluation of syncope. Amer J Med 1991;90:91-106. 3. Linzer M, et al. Clinical guideline: Diagnosing syncope: Part 2: Unexplained syncope. Ann Intern Med 1997;127:76-86. 4. Kapoor W. Evaluation and outcome of patient