Syncope associated with exercise, a manifestation of neurally mediated syncope.

A retrospective review of patients evaluated at a university-based referral hospital was performed to assess the basis for syncope associated with exercise in young patients. Over an 8-year period, 54 consecutive young patients (aged 12 to 30 years) were referred for evaluation of frank syncope. Twelve patients had syncope associated with exercise (group I) and 42 patients had syncope not associated with exercise (group II). Patients underwent physical examination, chest x-ray, 2-dimensional echocardiography, and in selected cases, cardiac catheterization. Head-up tilt-table testing was performed in 11 of 12 group I patients. Ten group I patients had no evidence of structural heart disease: 9 of these 10 (90%) developed syncope with tilt-table testing. Head-up tilt-table testing was performed in 41 of 42 group II patients: 34 (83%) developed syncope with tilt-table testing. Standard cardiac electrophysiologic study was performed in 9 of 12 group I and in 30 of 42 group II patients, and identified a basis for syncope in only 2 group I and 1 group II patients. Among 9 group I patients with a positive result on head-up tilt-table testing and no evidence of structural heart disease (mean follow-up 4.3 years), 7 are without further episodes of syncope; 3 have discontinued medication and 5 have resumed at least limited exercise. In conclusion, susceptibility to tilt-induced syncope was the most frequent finding in young patients without structural heart disease referred for evaluation of exercise-associated syncope. Tilt-table testing may be an important diagnostic tool for the evaluation of these patients.

Reproducibility of head-up tilt-table testing for eliciting susceptibility to neurally mediated syncope in patients without structural heart disease.

Head-up tilt testing has gained acceptance as a tool for assessing susceptibility to neurally mediated syncopal syndromes (e.g., vasovagal syncope), and is currently being evaluated as a means of testing therapeutic interventions in these conditions. To assess reproducibility of head-up tilt testing and thereby assess the potential of such testing for immediate evaluation of a planned treatment, findings during 2 sequential 80 degrees head-up tilt tests were compared in 23 patients (age range 6.5 to 74 years) undergoing evaluation of syncope of unknown origin. Upright tilt was performed initially in the absence of drugs, and repeated if necessary during pharmacologic provocation by means of isoproterenol infusions of 1 and 3 micrograms/min (tilt 1). End points were syncope, maximal tolerated isoproterenol dose, or a tilt duration of 10 minutes. The second tilt test (tilt 2) was conducted after approximately 30 minutes of supine rest using the maximal provocative conditions used in tilt 1. Fifteen of 23 patients (65%) developed syncope in either tilt 1 or 2, while 8 of 23 (35%) remained asymptomatic. Tilt testing results were concordant (i.e., positive in both tests, or negative in both tests) in 20 of 23 (87%) patients. Concordance was, however, less among tilt-positive patients (12 of 15, 80%) since 3 patients were tilt-positive in tilt 1 only.(ABSTRACT TRUNCATED AT 250 WORDS)

Tilt-table testing and syncope.

Syncope is a common clinical problem with multiple potential causes. Recent studies have delineated the natural history and most frequent causes of recurrent syncopal episodes. The medical history and detailed physical examination are particularly important. Clinical electrophysiologic testing has also played a critical role in assessing causes of syncope, but recent reports suggest that its value lies primarily in treating patients with evident underlying structural heart disease. Among patients without structural heart disease, the neurally mediated forms of syncope, particularly the emotional or vasovagal faint, are by far the most common basis for symptoms. In these patients, head-up tilt-table testing has proved particularly valuable in defining the origin of the problem and in assessing therapeutic alternatives. Protocols for upright tilt-table testing remain in evolution. Nonetheless, current practice suggests that 25-minute tilt-test duration is reasonable if pharmacologic provocation is to be used for further evaluation of patients with negative initial findings. However, for those laboratories that do not favor pharmacologic intervention, a 45-minute tilt-test duration is probably essential. Overall, tilt-table testing has proved relatively sensitive and appropriately specific for the identification of patients susceptible to neurally mediated syncopal syndromes.

Syncope: causes, clinical evaluation, and current therapy.

Syncope is a common clinical problem comprising the sudden loss of both consciousness and postural tone, with a subsequent spontaneous and relatively prompt recovery. Often it is difficult to differentiate a true syncopal spell from other conditions, such as seizure disorders, or from some simple accidents. Even more difficult is the identification of the cause of syncopal episodes. Nonetheless, establishing a definitive diagnosis ia an important task given the high risk of recurrent symptoms. Careful use of noninvasive and invasive cardiovascular studies (including electrophysiologic testing and tilt-table testing) along with selected hematologic, biochemical, and neurologic studies provides, in the majority of cases, the most effective strategy for obtaining a specific diagnosis and for directing therapy.