Blood Pressure during Supine Exercise in IdiopathicOrthostatic Hypotension

By ROBERT J. MARSHALL, M.D., ALEXANDER SCHIRGER, M.D.,AND JOHN T. SHEPHERD, M.D.

IDIOPATHIC orthostatie hypotension ischaracterized by an excessive fall in ar-

terial blood pressure on standing and by othermanifestations of an extensive loss of auto-nomic nervous function.

In the present study the arterial blood pres-sure was measured in seven patients withorthostatic hypotension during the perform-ance of mild leg exercise in the supine posi-tion. The finding of a pronounced fall in bloodpressure during and immediately after theexercise indicates that there is a major dis-turbance in the control of blood pressure evenin circumstances in which gravitational fac-tors are excluded.

MethodThe group of patients with idiopathic ortho-

static hypotension comprised four men and twowomen aged 50 to 61 years (table 1, cases 1 to 6).Studies were performed also in a man aged 44years who had recently undergone thoracolumbarsympathectomy for essential hypertension (table1, case 7).The patients exercised by pedaling a cycle

ergometer while in the supine position with thesupporting table horizontal. On four occasionsthe exercise was repeated with the table tilteddownward 15 degrees at the head end. Becausemost of the patients suffered from muscular weak-ness even when in the supine position, the exer-cise performed was mild, and it was carried outin periods of about 2 minutes. Oxygen consump-tion was measured in the two fittest patients dur-ing more prolonged periods of exercise; in thefirst patient (case 3), it increased from a restingvalue of 250 to 740 ml. per minute and in thesecond (case 5), from 260 to 530 ml. per minute.

From the Mayo Clinic and the Mayo Foundation,Rochester, Minnesota. The Mayo Foundation is apart of the Graduate School of the University ofMinnesota.

Supported in part by research grant H-4744 fromthe National Institutes of Health, U. S. PublicHealth Service.

Oxygen consumption was not measured in theremaining patients owing to the mildness, brevity,and occasional irregularity of the exercise, but itwas not likely to have increased by more than100 per cent. The blood pressure was recordedfrom the radial artery by a Statham strain-gagetransducer. The mid-chest level was taken as thezero reference point.

ResultsThe blood pressure in the supine position

was within normal limits for the age in sixpatients, ranging from 135 to 160 mm. ofmercury systolic and 60 to 85 mm. of mercurydiastolic; in the other patient it was 185/100(table 1). The pressures measured with thehead end of the table tilted downward by 15degrees were similar to those recorded in thehorizontal position.During exercise in the horizontal position

the arterial blood pressure was unchanged inone patient (case 5). The other patientsshowed striking falls in both systolic and dia-stolic pressures (figs. 1-3). The pressure beganto increase again in three patients (cases 3, 4,and 7) about 30 seconds after exercise was

stopped, and it returned to the original levelwithin 5 minutes. In the other three patients(cases 1, 2, and 6), however, it continued tofall for 20 seconds or more after the exercisewas stopped. In the four patients tested, a fallof comparable magnitude occurred while thesame exercise was performed with the tabletilted 15 degrees downward at the head end(table 1 and figs. 2b and 3b).

DiscussionThe abnormality of the arterial blood pres-

sure in patients with orthostatic hypotensionbecomes evident on changing from the supineto the standing position (table 1). Furtherevidence that the patients in the present studyhad severe loss of autonomic nervous function

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SUPINE EXERCISE IN ORTHOSTATIC HYPOTENSION

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Figure 1Systolic awnd diastolic blood pressures at radial artery during exercise in supine position(horizontal). Continuous line: during exercise. Interrupted line: before and after exercise.

was obtained from the response to the Val-

salva maneuver (fig. 4). Following release ofthe raised intrathoracic pressure no "over-shoot" of the arterial blood pressure occurred;instead, it returned slowly to its originallevel. A similar response was described pre-

viously in orthostatic hypotension' 2 and inother conditions involving interruption ofautonomic nervous pathways, such as tabesdorsalis3 and diabetic neuropathy,4 as well asafter thoracolumbar sympathectomy or theadministration of ganglion-blocking agents.2

Table 1Arterial Blood Pressure at Rest and During Exercise in Patients With OrthostaticHypotension

Supine, horizontal Supine, 15 degreesAge, (mm. Hg) head down (mm. Hg) Standing

Patient yr. Sex Rest Exercise* Rest Exercise* (mm. Hg)

1 55 M 135/60 90/30 - 60/402 50 F 185/100 140/70 70/453 52 M 160/85 110/55 160/85 110/50 25/154 61 M 140/85 100/50 145/70 95/45 40/255 58 F 150/70 155/70 - 65/406 61 M 150/80 90/40 145/80 95/50 70/407t 44 M 160/85 100/50 165/80 115/55 70/40*Values are lowest values obtained during, or shortly after termination of, exercise.I This patient had orthostatic hypotension after thoracolumbar sympathectomy for

hypertension.

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7MARSHALL, SCII1RGER, SHEPHERD

RADIALARTERY

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Figure 2Case 3. Blood pressure (nring exercise in sulpinle position in a patient with idiopathicorthostatic hypotension. a. Ilori5ontal sulinie position. b. Sutpine position with 15-degreehead-down tilt. Vertical lines are at 10-seconid intercals.

The findingg in five of six patients withidiopathic orthostatic hypotension of a pro-

nounced fall in blood pressure during mildleg exercise in the supine position, in whichthe effect of gravitational forces on the circu-lation is minimized, was unexpected. Indeed,

a similar fall in blood pressure occurred dur-ing exercise performed with the head end of

the table tilted downward; in this position thereturn of blood from the legs to the heart isai(led by gravity. In normal persons compen-

satory constriction occurs in resting vascularbeds during muscular exercise.5 6 It may bethat in patients with orthostatic hypotensionthis regulatory system is abolished,1 so that

the net peripheral resistance is lower than in

Circulation, Volume XXIV, July 1961

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SUPINE EXERCISE IN ORTHOSTATIC HYPOTENSION 7

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Figure 3

Case 7. Blood pressure durini~g exercise in supine position in a, patient who had had

thoracolumbar sympathectomy. a. Horizontal supine position. b. Supine position 'With

15-degree head-down tilt. Vertical lines are at 10-second intervals.

normal persons performing. comparable exer-

cise. Similar falls in systemic arterial blood

pressure have been noted dnring supine leg,

exercise after administration of the adrener-

gic-blocking. agents guanethidine7 and brety-

lium tosylate.sAn additional factor that had to be eon-

Circulation, Volume XXIV, July 1961

sidered was the possibility that partial or

complete denervation of the heart prevented

an adequate increase of cardiac output dur-

ing. exercise. Therefore, in two patients the

cardiac output was measured during the

second minute of exercise by the indicator-

dilution method. In one of these patients

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MARSHALL, SCHIRGER, SHEPHERD

NORMAL

INTRA - THORACIC F

PRESSURE 40(mm. Hg)

200

RADIAL ARTERY

(mm. Hg)

50

ORTHOSTATIC HYPOTENSION

s0

INTRA- THORACICPRESSURE 40k

(mm. Hg)i5r

RADIAL ARTERY

25

HEART RATE_ ai(beotsl/min.) t

IN TRA - THORACICPRESSURE 40r

(mm. Hg )

RADIAL ARTERY(mm. Hg)

HEART RATE(beats /min.)

Figure 4Effects of Valsalva maneuver in a normal subject(upper) and in two patients (cases 4, center, and6, lower) with idiopathic orthostatic hypotension.

(case 3), cardiac output increased from 4.7to 6.4 liters per minute and in the other(case 5), from 6.8 to 8.8 liters per minute.These increases were of the same order as

those obtained in normal subjects performingsimilar mild exercise. In the patient who hadhad thoracolumbar sympathectomy and inwhom the reflex nervous pathways to theheart were intact, the similar fall in pressure

during exercise must have been caused solelyby the failure of compensatory constriction ofother vascular beds.The effect of exercise in the supine position

on arterial blood pressure in patients withorthostatic hypotension can be contrasted withthat observed in patients with severe mitralstenosis. In the latter condition the cardiacoutput may be incapable of increasing; how-ever, despite dilatation of vessels in the activeskeletal muscles, the blood pressure is well

maintained owing to compensatory constric-tion in other vascular beds.5

Thus, although arterial blood pressure de-pends on both cardiac output and peripheralresistance, the results of this study suggestthat the reflex coordination of the variousvascular beds plays the major role in main-taining arterial pressure.

SummaryThe arterial blood pressure was measured

during exercise in six patients with idiopathicorthostatic hypotension. In five there was apronounced fall of arterial pressure while thesubjects exercised in the supine position on ahorizontal table. The systolic and diastolicpressures fell by an average of 50 and 32 mm.of mercury, respectively. During comparableexercise with the table tilted 15 degrees headdownward, the pressures fell to a similar de-gree. Thus, an abnormal response of bloodpressure occurred under conditions in whichvenous pooling was unlikely to be present.

It is suggested that the fall in blood pres-sure during exercise in the supine positionwas the result of failure of compensatory con-striction of other vascular beds and not offailure of the cardiac output to increase. Thus,the net peripheral resistance in such patientsis less than that in normal persons performingcomparable exercise.

AcknowledgmentWe wish to thank Dr. E. A. Hines, Jr., for his

interest and cooperation.

References1. STEAD, E. A., JR., AND EBERT, R. V.: Postural

hypotension: A disease of the sympatheticnervous system. Arch. Int. Med. 67: 546, 1941.

2. McINTosH, H. D., BURNUM, J. F., HICKAM, J. B.,AND WARREN, J. V.: Circulatory changes pro-duced by the Valsalva maneuver in normalsubjects, patients with mitral stenosis, andautonomic nervous system alterations. Circu-lation 9: 511, 1954.

3. SHARPEY-SCHAFER, E. P.: Circulatory reflexesin chronic disease of the afferent nervoussystem. J. Physiol. 134: 1, 1956.

4. SHARPEY-SCHAFER, E. P., AND TAYLOR, P. J.:Absent circulatory reflexes in diabetic neuritis.Lancet 1: 559, 1960.

5. MUTH, H. A. V., WORMALD, P. N., BIsHoP, J. M.,

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SUPINE EXERCISE IN ORTHOSTATIC HYPOTENSION

AND DONALD, K. W.: Further studies of bloodflow in the resting arm during supine legexercise. Clin. Se. 17: 603, 1958.

6. BLAIR, D. A., GLOVER, W. E., AND RODDIE, I. C.:Vasomotor reactions in the human forearmand hand during leg exercise. J. Physiol.,London 152: 17, 1960.

7. DOLLERY, C. T., EMSLIE-SMITH, D., AND MILNE,M. D.: Clinical and pharmacological studieswith guanethidine in the treatment of hyper-tension. Lancet 2: 381, 1960.

8. TAYLOR, S. H., AND DONALD, K. W.: The circula-tory effects of bretylium tosylate and guaneth-idine. Lancet 2: 389, 1960.

On Percussion of the ChestFirst Observation

OF THE NATURAL SOUND OF THE CHEST, AND ITS CHARACTER IN DIFFERENT PARTS

I. The thorax of a healthy person sounds, when struck. I deem it unnecessary to givein this place any description of the thorax. I think it sufficient to say that, by this term,I mean that cavity bounded above by the neck and clavicles, and below by the diaphragm:in the sound state, the viscera it contains are fitted for their respective uses.

II. The sound thus elicited (1) from the healthy chest resembles the stifled sound ofa drum covered with a thick woollen cloth or other envelope.

III. This sound is perceptible on different parts of the chest.-From On Percussionof the Chest. Published in 1761. Translated by John Forbes, M.D. In: Classics ofMedicine and Surgery. New York, Dover Publications, Inc., 1959, p. 125.

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ROBERT J. MARSHALL, ALEXANDER SCHIRGER and JOHN T. SHEPHERDBlood Pressure during Supine Exercise in Idiopathic Orthostatic Hypotension

Print ISSN: 0009-7322. Online ISSN: 1524-4539 Copyright © 1961 American Heart Association, Inc. All rights reserved.

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