The Effect of Beta-blocker Assessed by Repeat Head-up Tilt Test in Adults with Vasovagal Syncope or Presyncope

BACKGROUND: Oral beta-blocker is initially used to prevent the symptons in patients with vasovagal syncope or presyncope. But, beta-blocker treatment may actually cause worsening of symptoms in some patients. The purpose of the present study was to evaluate the efficacy of oral beta-blocker in preventing symptoms during repeat head-up tilt test in patients who had a positive response in initial head-up tilt test. METHOD: Patients. Among the 150 patients with unexplained syncope or presyncope who underwent head-up tilt from October 1994 to January 1996, forty-three patients, who were taking beta-blocker and underwent repeat head-up tilted test, were included in this study. Initial head-up tilt test. Each patients was tilted to the 70 degree upright position for 30 minutes. If the test was negative in the baseline tilt, intravenous isoproterenol was started at 1 (micro)g/min and then increased by 1 (micro)g/min every three minutes to al maximum of 5 (micro)g/min while maintaining 70 degree upright position. Repeat head-up tilt test. The test was repeated while each patients was taking atinolol. The repeat test was continued until reaching at the stage where each patient had a positive response in initial test. RESULTS: 1) In initial head-up tilt test, most (91%) of a positive response occured during isoproterenol provocation. 2) In repeat head-up tilt test on atenolol, thirty-four patients(79%) had a negative response. But nine patients(21%) still had a positive response. 3) Nonresponsive group showed younger age and shorter time period to a positive response in initial head-up tilt test than responsive group. CONCLUSION: It may be useful to assess the effectiveness of beta-blocker by repeat head-up tilt before deciding long term treatment, especially younger age group.

Usefulness of Head-up Tilt Test in Adults with Syncope or Presyncope of Unexplained Origin

BACKGROUND: Vasovagal syncope is a common cause of syncope. In some cases, syncopal episode is recurrent, resulting in physical injury. Head-up tilt test with or without isoproterenol provocation has been a tool to diagnose vasovagal syncope. But the protocol of head-up tilt test has not been settled. In this study, we evaluate the usefulness of a head-up tilt test with isoproterenol provocation in patients with syncope or presyncope of unexplained origin. METHODS: Head-up tilt test was performed with patients in the fasting state in the morning. After supine heart rate and blood prewwure were obtained, each patient was tilted to the 70 degree upright position for 30 minutes using a motorized tilt table with a footboard. If the test was negative in the baseline tilt, intravenous isoproterenol was started at 1 microg/min and then increased by 1 microg/min every three minutes to a maximum of 5 microg/min while maintaining 70 degree upright position. The end points of test were positive response, intolerance of isoproterenol, heart rate>150 beats/min, and completion of the protocol. When an end point reached, the patient was rapidly returned to the horizontal position. RESULTS: 1) Of 122 patients with syncope or presyncope, 113 patients(93%) had prodromal symptoms. 2) 23 patients(19%) had physical injury during episode. 3) 93 patients(76%) experienced episodes while they were standing or sitting. 4) A total of 83 patients(68%) had a positve response during head-up tilt test ; 7 patients(8%) of these 83 patients had a positive response during the baseline tilt. But, 76 patients(92%) required isoproternol provocation to elicit this response. 5) The pattern of positive response showed vasodepressive pattern in 55 patients(67%), mixed pattern in 26 patients(31%), and cardioinhibitory pattern in 2 patients(2%). 6) No significant side effect of isoproterenol was noted. 7) There were no significant differences between positive response group and negative response group in terms of clinical characteristics and hemodynamic findings during head-up tilt test. CONCLUSION: A head-up tilt test with isoproterenol provocation could be an useful tool for diagnosing vasovagal syncope or presyncope in adults.