title: Abnormal responses to orthostatic testing in children and adolescents with recurrent unexplained syncope.
abstract: Syncope in the pediatric age group is a frequent event. Most often the cause is readily apparent--i.e., orthostatic hypotension or a vasovagal event. However, there are a large number of children with frequent recurrent unexplained syncope. Neither history, physical examination, nor standard testing reveals a cause. One hundred four consecutive patients were evaluated by orthostatic testing after standard methods found no cause for the recurrent syncope. Forty-seven (44%) of these 104 patients had syncope produced by orthostatic testing. Twenty-six of the 47 (55%) became syncopal within 5 minutes of testing initiation and 21 of the 47 (45%) after 5 to 11 minutes of testing. These patients had an average decrease of 81.5 mm Hg in blood pressure and a 25 beat/min decrease in heart rate. Of 12 control subjects, none lost consciousness with standing times as long as 14 minutes. Pacing was ineffective in preventing syncope, as two patients with a previously implanted normally functioning pacemaker had recurrent syncope clinically. Syncope was also induced by orthostatic testing, with the pacemaker showing a normal response with pacing as the patient became bradycardic. The syncopal event produced by orthostatic testing occurred with a downward blood pressure trend and a narrowing of the pulse pressure without a significant increase in heart rate. This was followed by a sudden drop in blood pressure and then by bradycardia. There is a group of children and adolescents with recurrent unexplained syncope due to abnormal orthostatic control mechanisms. Orthostatic testing appears helpful in identifying these patients.
authors.affiliation: Department of Pediatrics, Children's Hospital of The King's Daughters, Norfolk, VA 23507.
authors.forename: B A
authors.initials: BA
authors.lastname: Ross
authors.forename: S
authors.initials: S
authors.lastname: Hughes
authors.forename: E
authors.initials: E
authors.lastname: Anderson
authors.forename: P C
authors.initials: PC
authors.lastname: Gillette
mesh_terms: D000293:Adolescent; D002304:Cardiac Pacing, Artificial; D002648:Child; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007024:Hypotension, Orthostatic / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D011187:Posture / Q000502:physiology*; D012008:Recurrence; D013575:Syncope / Q000209:etiology* / Q000503:physiopathology; D013997:Time Factors