The head-up tilt table test in patients with syncope of unknown origin

Strasberg, Boris; Rechavia, Eldad; Sagie, Alex; Kusniec, Jairo; Mager, Aviv; Sclarovsky, Samuel; Agmon, Jacob

doi:10.1016/0002-8703(89)90225-1

Cited by 125 publications

(19 citation statements)

References 8 publications

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“…The mean incidence of a tilt-induced asystole observed in these specific studies (15%, with a range from 4% to 33%) is similar to that extrapolated from other more general studies on tilt-table test (18%, 141 patients out of 794; range, 6%-48%) [5,6,8,10,25,[33][34][35][36][37][38][39][40][41][42][43][44][45] . The incidence was higher during nitrate provocation test (21%, 103 out of 489 patients) [5,6,10,[40][41][42][43]45] than during passive head-up tilt test (14%, 78 out of 568 patients) [25,[27][28][29][33][34][35]39] and isoproterenol test (13%, 34 out of 265 patients) [8,15,16,30,36,37,44] . The mean duration of asystole ranged from 7 to 30 s (mean, 14 s) [6,8,10,[15][16][17]25,[27]…”

supporting

confidence: 84%

Tilt-induced asystole: a useful prognostic marker or clinically unrelevant finding?

Raviele¹

2002

European Heart Journal

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supporting

confidence: 84%

Tilt-induced asystole: a useful prognostic marker or clinically unrelevant finding?

Raviele¹

2002

European Heart Journal

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“…Studies of the passive tilt test show a positive response rate of 26% to 75%. 7,[13][14][15] The rate of positive response for the passive tilt test was 1.3% (1 / 78) in the present study. The discrepancy between the positive response rates of the present study and above mentioned studies may be related to the different protocols used.…”

Section: Discussionsupporting

confidence: 45%

“…Some studies reporting the time to the development of a positive response found the average time was 30 minutes for a 60-degree tilt and 10 minutes for an 80-degree tilt. [7][8][9]13,14,16,19) Our data showed that the average time to the development of a positive response was 4.3 ± 2.9 min for an 80-degree tilt in 73 patients. The pathophysiologic mechanism of N-M syncope is not fully understood.…”

Section: Discussionmentioning

confidence: 57%

<b>Usefulness of Head-up Tilt Test in the Evaluation and Management of Unexplained Syncope or Pre-syncope</b>

Fang

Kuo

2000

Jpn Heart J

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SUMMARYThis study included 87 consecutive patients with unexplained syncope or pre-syncope who had undergone the head-up tilt (HUT) test with concomitant isoproterenol infusion. A positive response was defined as development of syncope or pre-syncope in association with substantial hypotension (decline of systolic blood pressure > 20 mmHg). Coronary artery spasm was suggested from the clinical symptoms and electrocardiographic findings in 1 patient (1 / 87 = 1.1%). Intolerance to isoproterenol infusion was noted in 8 cases (8 / 87 = 9%). Of the 78 patients who completed the study, 73 showed positive responses (73 / 78 = 94%). (baseline systolic blood pressure = 125 ± 23 mmHg vs endpoint systolic blood pressure = 76 ± 11 mmHg, p < 0.05; baseline heart rate = 73 ± 14 beats per minute vs endpoint HR = 80 ± 24 beats per minute, p < 0.05). In 73 patients who showed positive responses, the systolic blood pressure (SBP) and heart rate (HR) returned to a safe level at 2 minutes when the patients were returned to a supine position (post-study 2 minutes SBP = 124 ± 18 mmHg vs baseline SBP = 125 ± 23 mmHg, p = NS; post-study 2 minutes HR = 82 ± 18 beats per minute vs baseline HR = 73 ± 14 beats per minute, p < 0.05). All 73 patients with a positive HUT test received Atenolol therapy (50 mg daily). Only 35 of these 73 patients took Atenolol regularly and had a repeat HUT test. After atenolol therapy, persistent positive responses were observed in 19 cases (19 / 35 = 54%) and negative responses were noted in 16 cases (16 / 35 = 46%). The mean dosage of isoproterenol needed to provoke a positive HUT test in 19 patients who had received Atenolol therapy and had a positive repeat HUT test was 2.3 ± 1.2 µg / min at baseline and 3.5 ± 0.9 µg / min for post-Atenolol therapy (p < 0.001). Sixteen patients with a negative repeat HUT test were treated continuously with Atenolol and followed for a mean period of 13 ± 11 months (range, 1-34 months). All 16 patients were free of syncope or pre-syncope during the period of follow up. In conclusion, the HUT test is mostly well tolerated and safe, even though the test has a low rate of adverse effects. Atenolol is effective for the prevention of provoked or spontaneous recurrent syncope or pre-syncope. (Jpn Heart J 2000; 41: 623-631)

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“…2 Although incompletely understood, these vasovagal episodes are thought to be triggered by increased afferent neural traffic arising from accentuated ventricular and aortopulmonary mechanoreceptor activities.3-5 Mechanoreceptor activation is thought to be the consequence of a rapid reduction in ventricular volume accompanied by an increase in ventricular rhage.5 '6 In both vasovagal syncope and severe hemorrhage, hypotension occurs secondary to increased peripheral vascular dilation and bradycardia, possibly secondary to accentuated efferent parasympathetic tone (although the exact neural mechanism of the dilation is unknown).7'8 A number of reports have indicated that head-upright body tilt may be useful in unmasking susceptibility to vasovagally mediated hypotension and bradycardia in patients with unexplained syncopal episodes. [9][10][11] In addition, the technique has been used to assess the efficacy of prophylactic therapy used to diminish the frequency of syncopal episodes.12 The effect of vasovagal syncope on cerebral blood flow, both before and during loss of consciousness, has been largely unexplored. Measurement Initial, velocity at initial head-up tilt; % A, percent change from initial tilt to tilt-induced syncope expressed as an absolute number; pulsatility index, systolic velocity minus diastolic velocity divided by mean velocity; resistance index, systolic velocity minus diastolic velocity divided by systolic velocity.…”

mentioning

confidence: 99%

Cerebral vasoconstriction during head-upright tilt-induced vasovagal syncope. A paradoxic and unexpected response.

et al. 1991

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BACKGROUND To determine the effect of vasovagally mediated syncope on the cerebral circulation, transcranial Doppler sonography was used to assess changes in cerebral blood flow velocity during head-upright tilt-induced syncope. METHODS AND RESULTS Thirty patients (17 men and 13 women; mean age, 43 +/- 22 years) with recurrent unexplained syncope were evaluated by use of an upright tilt-table test for 30 minutes, with or without an infusion of intravenous isoproterenol (1-4 micrograms/min), in an attempt to provoke bradycardia, hypotension, or both. Transcranial Doppler sonography was used to assess middle cerebral artery systolic velocity (Vs), diastolic velocity (Vd), ratio of systolic to diastolic velocities, pulsatility index (PI = Vs-Vd/Vmean), and resistance index (RI = Vs-Vd/Vs) before, during, and after tilt. Syncope occurred in six patients (20%) during the baseline tilt and 14 (46%) during isoproterenol infusion (total positives, 66%). In the tilt-positive patients, concomitant with the development of hypotension and bradycardia, transcranial Doppler sonography showed a 75 +/- 17% decrease in diastolic velocity, unchanged systolic velocity, a 46 +/- 17% decrease in mean velocity, a 295 +/- 227% increase in pulsatility index, and a 73 +/- 34% increase in resistance index. CONCLUSIONS These findings reflect increased cerebrovascular resistance secondary to arteriolar vasoconstriction distal to the insonation point of the middle cerebral artery. This is paradoxic because the expected response of the cerebral circulation to hypotension is vasodilation. We conclude that abnormal baroreceptor responses triggered during vasovagal syncope result in a derangement of cerebral autoregulation with paradoxic vasoconstriction in the face of increasing hypotension.

show abstract

The head-up tilt table test in patients with syncope of unknown origin

Cited by 125 publications

References 8 publications

Tilt-induced asystole: a useful prognostic marker or clinically unrelevant finding?

Tilt-induced asystole: a useful prognostic marker or clinically unrelevant finding?

<b>Usefulness of Head-up Tilt Test in the Evaluation and Management of Unexplained Syncope or Pre-syncope</b>

Cerebral vasoconstriction during head-upright tilt-induced vasovagal syncope. A paradoxic and unexpected response.

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