tilt test for diagnosis of unexplained syncope in pediatric

1991;87;334PediatricsOtto G. Thilenius, Jose A. Quinones, Tarek S. Husayni and Janet NovakTilt Test for Diagnosis of Unexplained Syncope in Pediatric Patients

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334 PEDIATRICS Vol. 87 No. 3 March 1991

Tilt Test for Diagnosis of Unexplained Syncopein Pediatric Patients

Otto G. Thilenius, MD, PhD; Jose A. Quinones, MD; Tarek S. Husayni,MD; and Janet Novak, RN

From the Christ Hospital and Medical Center, Oak Lawn, and The Heart Institute forChildren, Pa/os Heights, Illinois

ABSTRACT. Thirty-five teenage patients with a historyof presyncope or syncope underwent passive head-uptilting to reproduce symptoms of syncope. If tilting alone

did not induce syncope, isoproterenol infusion was given

to increase heart rate to 150 to 160 beats per minute. In80% of patients with a history of syncope, identicalsymptoms could be reproduced during tilting: an abruptfall in blood pressure combined with profound nodalbradycardia, ranging from 32 to 86 beats per minute.These symptoms were quickly reversed by returning the

patient to the supine position. For patients with frequentoccurrences of syncope, especially when there was a his-tory of trauma sustained during these episodes, a thera-peutic regimen of either fi blockers or 9a-fluorocortisolwas begun. The mechanism of this common cause of

syncope in childhood is neurocardiogenic in response tovenous pooling and catecholamine-induced tachycardia.

The tilt test is an excellent and cost-effective test for theworkup of unexplained syncope in childhood. Pediatrics

1991;87:334-338; orthostatic hypotension, nodal bradycar-

dia, tilt test, syncope.

Syncope in the pediatric age range is for most

parents and practicing physicians an alarming

symptom. The child, usually a teenager, will typi-cally be hospitalized for extensive workup. Neurol-

ogy consult, electroencephalogram, computed to-

mographic scan, Holter monitoring, even “routine”

cardiac catheterization and electrophysiologic stud-ies usually yield little, if any, useful information.

Already in 1982, Kapoor et al’ called for a more

cost-effective approach to the diagnostic workup.Although syncope occurs in all age-groups, thereappear to be two major groups in which it occurs:

Received for publication Nov 7, 1989; accepted Mar 13, 1990.

Reprint requests to (O.G.T.) 2638 Gordon Dr, Flossmoor, IL60422.

PEDIATRICS (ISSN 0031 4005). Copyright © 1991 by the

American Academy of Pediatrics.

teenagers2 and adults older than 50 years.35 In

recent years the head-up tilt test has been reported

as a useful diagnostic test for adults.5’#{176} To date we

have found no study using the tilt protocol for the

pediatric age-group. We modified this protocol

slightly; it is an outpatient procedure for evaluation

of patients with presyncope or syncope. In this

paper we report the initial results of this test andour therapeutic approach to this problem.

METHODS AND PATIENT SELECTION

Thirty-five patients (17 boys, 18 girls; 8 to 19

years of age) were referred for evaluation; 6 of these

patients had spells of dizziness or blacking out (loss

of vision without loss of muscle tone); 29 had epi-

sodes of complete loss of consciousness. Most of

these patients had repeated episodes; some had

sustained minor injuries when falling; one girl had

such frequent episodes that she was unable to at-

tend school. These episodes occurred while patients

were in the upright position and were not accom-

panied by focal neurologic symptoms. In some cases

episodes occurred in context with physical exertion.

The past history of these patients was otherwise

unremarkable. All patients had a thorough physical

examination. Whereas some patients were referred

for the tilt test after extensive neurologic testing

was negative, more recent referrals had only an

electrocardiogram and echocardiogram. None of our

patients had cardiac disease. In three families more

than one member had episodes of syncope.

Tilt Protocol

Our aim was to develop a useful, efficient tiltprotocol. We found it impractical to use prolonged

supine resting periods or extensive (60 minutes) tilt

periods. We also found no use for partial tilt such

as 30#{176}or 45#{176}.Our tilt protocol (Table 1) takes 30



Co Hr�[.llftiI I �‘ APR.�c�M

1*1.41

6d� 4.4o�’��’r�i. . ��

‘R 1p56:10 DELAY

TABLE 1. Tilt Protocol* .�.. I � APR � DELAY HR6O

ARTICLES 335

1. Supine resting state for 10 mm.2. Tilt to 60#{176}for 10 mm; record symptoms.3. Return patient to supine position; after 2-3 mm start

isoproterenol infusion at 1 �zg/min; when isoprotere-nol effect is apparent and consistent, re-tilt to 60#{176}.

4. 60#{176}tilt for 5-10 mm; if no symptoms, increase iso-

proterenol to 2 �ig/min for 2-3 mm, then 3, 4, and,maximally, 5 �g/min until a heart rate of 150-170

beats/mm is reached.5. When you decide to terminate the test, discontinue

isoproterenol first (if symptoms permit); after isopro-terenol effect wears off, return patient to supine posi-tion.

6. Record recovery for 3-5 mm.

* Record blood pressure and electrocardiographic rhythm

strip every 2 mm (time and heart rate should be printed

on strip). The test may be terminated whenever symp-toms require it, but try to record a full tilt response,preferably with loss of consciousness. When patientshows signs of incipient syncope (drop in heart rate),turn on electrocardiographic recorder to record rhythmand rate as well as time.

to 60 minutes, depending on how rapidly a “posi-tive” test can be induced. An intravenous drip is

needed for administration of isoproterenol. Through-out the test the electrocardiogram is continuouslymonitored. A lead with a clearly visible P wave is

selected. The electrocardiogram, including time and

heart rate, is printed out every 2 minutes. Bloodpressure readings (by cuff) are recorded every 2

minutes, together with comments such as degree of

tilt, medication, patient symptoms, etc. The tests

were done in a radiologic suite where motorized

tables that tilt from the supine to the upright po-sition are standard equipment.

Definitions and Test Interpretation

The vasodepressor response consists of presyn-cope or syncope. Presyncope are vasovagal symp-toms, subjective and objective: the patient does not

feel well; may experience dizziness, with or withoutblackout; is cold, sweaty; has a thready pulse andlow blood pressure; but does not lose consciousness.In syncope, presyncopal symptoms are followed by

loss of muscle tone and consciousness. Test results

can be negative (normal), positive, or borderline.The typical normal test result in a teenage pa-

tient is characterized by a resting heart rate of 60to 70 beats per minute (sinus rhythm) and a bloodpressure of 110/70 mm Hg in supine position (Fig.

1). Upon 60#{176}upright tilt the heart rate rises to 80to 90 beats per minute with a small, transient fallin blood pressure. Return to the supine position

reestablishes baseline values. Isoproterenol infu-

sion of 1 �.zg/min increases the heart rate to 100 to

110 beats per minute. Adding 60#{176}tilt increases the

I I � I I I � � I I � I � � � J I � �L

$oz�a1 Tilt St,�y _______________________Ii.tor3� of blackinq out vitliout loss of COii.cLou.n..�1S1IS11�SSSPI&

�F{tLWL �ILU1t1ft�‘H� � � � � i I I I I I I I I ‘ i�

!!‘Dlk � 4� HIoraal tilt study Ms#{248}� tHistory of blackinq out without loss of consciou.nss

Fig 1. A, Normal (negative) response to tilt test. Panel1: baseline electrocardiogram; heart rate 60 beats perminute (bpm). Panel 2: response to 60#{176}tilt; heart rate 83

bpm. Panel 3: return to supine position; heart rate 51bpm. Panel 4: isoproterenol effect in supine position;heart rate 110 bpm. B, Normal (negative) response to tilttest. Panel 1: 60#{176}tilt during isoproterenol infusion; heart

rate 153 bpm. Panel 2: 60#{176}tilt during maximal isoproter-enol infusion; heart rate 164 bpm. Panel 3: 60#{176}tilt;isoproterenol infusion discontinued; heart rate 141 bpm.Panel 4: return to supine position; heart rate 77 bpm.

heart rate further, but sinus rhythm is present atall times. The heart rate can be increased to 140 to

160 beats per minute with higher isoproterenol

doses. After discontinuation of isoproterenol and

return to the supine position, resting values return.The blood pressure changes little throughout the

test.

A positive result (Fig. 2), either without or withisoproterenol infusion, shows initially the same

normal increase in heart rate during 60#{176}tilt. A few



336 UNEXPLAINED SYNCOPE

minutes later, however (typically within 3 to 10

minutes), presyncope supervenes. Nodal bradycar-

dia with a full vasovagal response is observed. Thesesymptoms, which are reproducible, are quickly re-

versed by return to the supine position.

A borderline result has unusually wide swings inblood pressure and heart rate (>15 mm Hg and >15beats per minute); the patient feels dizzy whenasked, but is without visible signs of a vasovagal

reaction.

RESULTS

Twenty-six patients had positive results, 3 stud-

ies were borderline, and 7 were negative. In positive

studies the average heart rate during the vasode-

pressor reaction was 58 beats per minute; the

rhythm was (with one single exception) nodal. The

acuteness of the full reaction was striking: the

precipitous drop in heart rate often occurred within

10 to 15 seconds.

Of the 6 patients with a history of presyncope(Table 2), 3 had a normal tilt response, 1 responsewas borderline, and 2 were positive. By contrast, a

positive response was seen in 24 of the 29 patients

Fig 2. Positive response to tilt test. Panel 1: baselineelectrocardiogram; heart rate 72 beats per minute (bpm).

Panel 2: early response to 60#{176}tilt; heart rate 112 bpm.Panel 3: fifth minute of 60#{176}tilt; presyncope. Panel 4: 10seconds later: full syncope with profound nodal brady-cardia.

TABLE 2. History and Results of Tilt Test

History Resu lt (No. of Patients)

Normal Borderline Positive

Lightheadedness 2 0 0

Blackout 1 1 2Loss of consciousness 4* 1 24

* Two patients (1 1 and 8 years old) were unable to stand

still.

with a history of syncope, 1 patient had a borderline

response, and 4 had negative results.

The resting heart rate (Table 3) and the initial

response to passive tilt were identical for positive

and negative responders. During isoproterenol in-

fusion the heart rates of patients with negative or

borderline responses rose to 130 to 160 beats per

minute. In patients with positive tilt responses

maximal heart rates prior to presyncope were 76 to

130 beats per minute (with two exceptions of 150

and 160 beats per minute).

Of 25 positive studies (Table 4), the test was

terminated during profound presyncope in 13 pa-

tients and during full syncope in 12 patients. The

vasodepressor reaction became apparent 4 to 9 mm-

utes after start of tilt for those patients who did

not receive isoproterenol infusion.

fl-Blockade therapy was prescribed for 15 pa-

tients who had positive responses to tilting. Repeat

tilt studies were done in 6 patients. Five of these

had a normal (negative) response. The sixth patient

was markedly improved. Before therapy she had

often experienced several syncopal episodes per

day, but she had none during therapy (10 months);

blackout without loss of consciousness occurred

occasionally. During therapy she tolerated tilting

alone normally. During isoproterenol infusion (2

�zg/min) presyncope developed only with sinus

bradycardia (62 beats per minute): In none of these

patients did isoproterenol infusion achieve heart

rates of more than 130 beats per minute.

DISCUSSION

Syncope caused by vasodepressor reaction (neu-

rocardiogenic syncope) is an old problem; its differ-

ential diagnosis has been reviewed.”12 Other causes

of syncope commonly seen in adult patients (yen-

tricular arrhythmias, atrioventricular block, sick

sinus syndrome) or associated diseases (hyperten-

sion, myocardial infarction, or diabetes)’316 are vir-

tually absent in childhood. None of our patients

had underlying heart disease. Malignant vasovagal

syncope resulting in extended asystole9 is probably

a rare exception. Erect position has been used toinduce vasodepressor responses17”8 but can cause

problems when syncope ensues. The head-up tilt,

without or with the additional challenge with iso-

proterenol, has been a simple and effective tool in

diagnosing patients who are prone to vasodepressor

reactions. We consider it the first step in the

workup of an older child with syncope. Once this

diagnosis has been confirmed, the patient and fam-

ily can be reassured that this is not a disease in the

usual sense, but a normal albeit paradoxical and

extreme physiologic reaction.



TABLE 3. Heart Rates During Tilt Study*

ARTICLES 337

Tilt Response Normal Tilt Responseor Borderline Positive

Supine (mean ± SD) 68 ± 11 72 ± 10

60#{176}tilt (mean ± SD) 91 ± 11 94 ± 6Maximal heart rate with isoproterenol (range) 130-160Maximal heart rate prior to syncope (range)

24 patients 76-1302 patients 150-160

Minimal heart rate during syncope (range) 32-86

* Results are given in beats per minute.

TABLE 4. Conditions Inducing Presyncope or Syncope*

Tilt Only Isoproterenol Infusion (�sg/min)

1 2 3 4 5

Presyncope 6 4 2 0 2 1Syncope 7 1 0 0 1 1

* Results are numbers of patients.

The mechanism of this reaction6’#{176} begins withreduced left ventricular filling, secondary to poolingofblood in the lower parts ofthe body during tilting.This reduction in left ventricular volume, especially

when combined with the inotropic effect of isopro-

terenol, results in stimulation of left ventricularmechanoreceptors. Increased afferent neural activ-ity causes reflex slowing of heart rate and vasodi-

lation, a paradoxical response seen in those patients

who are prone to the vasodepressor response. Thishypothetical sequence of events is the basis for

treatment of these patients with fi blockers (block-ade of inotropic and chronotropic effects of catech-olomines).

It is striking to observe the sequence of thesephysiologic reflexes: there is the normal rise inheart rate by 10 to 20 beats per minute in response

to tilting, with little change in blood pressure; this

level of tachycardia is maintained for several mm-

utes until a precipitous seemingly simultaneous fall

in blood pressure and heart rate supervenes. Theelectrocardiogram shows complete cessation ofsinus activity and profound nodal bradycardia. Va-

sovagal symptoms are evident. Return to the supineposition reverses this process promptly. It is equally

fascinating to observe the wide range of suscepti-bility and expression of this vasovagal reaction.

Some patients exhibit the full vasovagal response

with tilt alone; others have a positive tilt responseonly with the additional isoproterenol-induced

tachycardia; again others show extensive fluctua-tion in heart rate and blood pressure without a full-fledged vasodepressor reaction. This “borderline”

response indicates a transient instability in heart

rate control which we consider an incomplete

expression of a vasodepressor response.

It is of interest that patients with a history of

only presyncope usually had a normal (negative)

tilt response. For patients with a history of syncopethe demonstration of a positive response, duplicat-

ing the child’s known symptoms under controlled

circumstances, is diagnostic and reassuring for allinvolved parties. It should be noted that for most

patients presyncope became evident at relatively

low heart rates, 76 to 130 beats per minute.

THERAPY

Whereas pacemaker implantation may havemerit in selected patients,2’9”8”9 most authors haveused f3 blockade to interrupt the physiologic se-quence leading to neurocardiogenic syncope. Thisapproach has been successful. After acute or

chronic autonomic blockade, vasodepressor symp-

toms could no longer be induced8”9 or were signifi-cantly attenuated.

Whether a “positive tilter” needs to be givenmedication will depend on the frequency of vaso-

depressor reactions. For the child who occasionally

passes out in church or under similar circum-

stances, only reassurance is used. The patient, whois usually quite aware of presyncopal symptoms,

should lie down rather than fight this reaction with

willpower. However, for more frequent episodes,

especially when associated with physical exertion,or when there is a history of trauma sustained

during syncope, we have used medication as well asreassurance. Seventeen of our patients have had

drug therapy. Atenolol (25 or 50 mg every day) is

our first choice (12 patients); long-acting propran-olol (80 mg every day) was used for 3 patients. For

2 patients, who wish to be very active in sports, we



338 UNEXPLAINED SYNCOPE

opted for 9a-fluorocortisol (0.1 mg every day) andsalt supplement as blood volume expander. All pa-

tients except 1 have shown complete suppression

of syncope. In 1 child, who had neurocardiogenicsyncope even while receiving 50 mg of atenolol, wechanged the medication to metoprolol (50 mg everyday). As this is a preliminary report the durationof drug therapy and the possible difference between

f3 blockers and 9a-fluorocortisol are unanswered

questions.

REFERENCES

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diagnostic evaluation. JAMA. 1982;247:2687-2691

2. Sapire DW, Casta A. Vagotonia in infants, children, adoles-cents and young adults. Int J Cardiol. 1985;9:211-222

3. Hammill SC, Holmes DR Jr, Wood DL, et al. Electrophys-iologic testing in the upright position: improved evaluationof patients with rhythm disturbances using a tilt table. J

Am Coil Cardioi. 1984;4:65-71

4. Kenny RA, Ingram A, Bayliss J, Sutton R. Head-up tilt: auseful test for investigating unexplained syncope. Lancet.

1986;1:1352-1354

5. Abi-Samara F, Maloney JD, Fouad-Tarazi FM, Castle LW.The usefulness of head-up tilt testing and hemodynamicinvestigations in the workup of syncope of unknown origin.Pace. 1988;11:1202-1214

6. Rechavia E, Strasberg B, Agmon J. Head-up tilt table eval-uation in a trained athlete with recurrent vaso-vagal syn-cope. Chest. 1989;95:689-691

7. Almquist A, Goldenberg IF, Milstein 5, et al. Provocationof bradycardia and hypotension by isoproterenol and uprightposture in patients with unexplained syncope. N EngI JMed. 1989;320:346-351

8. Waxman MB, Yao L, Cameron DA, Wald RW, Roseman J.Isoproterenol induction of vasodepressor-type reaction invasodepressor-prone persons. Am J Cardiol. 1989;63:58-65

9. Maloney JD, Jaeger FJ, Fouad-Tarazi FM, Morris HH.Malignant vasovagal syncope: prolonged asystole provokedby head-up tilt. Cleve J Med. 1988;55:542-548

10. Chen MY, Goldenberg IF, Milstein S, et al. Cardiac electro-physiologic and hemodynamic correlates of neurally me-diated syncope. Am J Cardiol. 1989;63:66-72

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12. Susman J. Orthostatic hypotension. Am Fam Physician.

1988;37:1 15-118

13. Kapoor WN, Karpf M, Wienand 5, Peterson JR, Levy GS.A prospective evaluation and follow-up of patients withsyncope. N EngI J Med. 1983;309:197-204

14. Johnson WB, Milstein 5, Reyes WJ, et al. Head-up tilttesting for diagnostic evaluation of syncope of unknown

origin. Circulation. 1989;80(Suppl II):656

15. Denes P, Urety E, Ezri MD, Barbola J. Clinical predictorsof electrophysiologic findings in patients with syncope ofunknown origin. Arch Intern Med. 1988;148:1922-1928

16. Bass EB, Elson JJ, Fogoros RN, et al. Long term prognosisofpatients undergoing electrophysiologic studies for syncopeof unknown origin. Am J Cardiol. 1988;62:1186-1191

17. Streeten DH, Anderson GH, Richardson R, Thomas FD.Abnormal orthostatic changes in blood pressure and heartrate in subjects with intact sympathetic nervous function:evidence for excessive venous pooling. J Lab Clin Med.

1988;11 1:326-33518. Brignole M, Menozzi C, Lolli G, Sartore B, Barra M. Natural

and unnatural history of patients with severe carotid sinushypersensitivity: a preliminary study. Pace. 1988;1 1(ptII):1628-1635

19. Wyhe GV, McKinnie J, Avitall B, et al. Unexplained dis-cordance between acute intravenous and long term oral betablockade for control of neurocardiogenic dysfunction diag-nosed during head up tilt testing. Circulation. 1989;80(suppl

II):656

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1991;87;334PediatricsOtto G. Thilenius, Jose A. Quinones, Tarek S. Husayni and Janet NovakTilt Test for Diagnosis of Unexplained Syncope in Pediatric Patients

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