Further studies on the cardiovascular status of normal newborn infants

F U R T H E R S T U D I E S ON T H E C A R D I O V A S C U L A R S T A T U S OF NORMAL N E W B O R N I N F A N T S IV.

E F F E C T OF ADRENALI:]NE, ACETYLCHOLINE, ] 0 P E R CENT OXYGEN, AND 1 0 0 P E R C E N T OXYGEN ON THE ELECTROCARDIOGRAM

CLAUDE D U P U I S ,

M.D., ~ B~ACQ DuPuIs, M.D., '~ FORREST ]7[. ADAMS, M.D., *~:' M.D., AND TUOMAS PELTONEN, M.D.

JOHN LIND,

NFORMATION accumulated recently ~-6 indicates that the cardiovascular system of the normal newborn infant adjusts gradually over a period of several days rather than within minutes after birth as previously supposed. 7 The change from the fetal type of circulation to the newborn cirr is probably brought about by the following factors: an increase in systemic resistance; a decrease in pulmonary resistance; an increase in the arterial oxygen saturation; and other less well-defined factors. s Associated with these fundamental changes in the cardiovascular system is the presence of a large leftto-right shunt through the ductus arteriosus at rest s' 5, 6 and a right-to-left shunt with crying ~' 4 and right ventricular and pulmonary a r t e r y hypertension2, 6 During this period of adjustment, the newborn infant's cardiovascular system responds to adrenaline and noradrenaline with an increase

I

F r o m the ~Venner-Gren Cardiovascular Research Laboratory, Norrtull's Hospital, Stockholm, Sweden; the Department of Pediatrics, University of California at Los Angeles; and the Cardio-Respiratory Research Unit, University of Turku, Finland. Supported by funds from the Los Angeles County H e a r t Association and the Association for the Aid of Crippled Children, New York. *From the Children's Clinic, Cite Hospitali@re, Lille, F r a n c e (Professor A. Bretton). **Department of Pediatrics, University of California School of Medicine, Los Angeles 24, Calif.

in right ventricular and pulmon a r y a r t e r y pressure; and adrenaline produces a tachyeardia whereas noradrenaline produces a bradycardia2 Acetylcholine, 100 per cent oxygen, and 10 per cent oxygen with 90 per cent nitrogen appear to produce no significant effect on the right ventricular pressure of such infants2 These responses and findings in the normal newborn infant have been found to be somewhat different from those obtained in newborn animals. 1~ 1~ The complexity of direct measurement of right heart pressures, shunts, and resistance suggests the need for simpler methods of measuring these changes. F o r these reasons, it seemed of interest to evaluate the role of the electrocardiogram in such studies. Ziegler 1~ has recently reported tile electrocardiographic changes during the first few hours and days of life as part of an over-all survey of the electrocardiographic findings in normal infants and children. In this conneetion, James ~3 has suggested that the T wave in unipolar Lead V1 may reflect in part the pressure in the right ventricle and pulmonary artery. This paper presents the results of an investigation on the effects of adrenaline, aeetylcholine, 100 per cent oxygen, 649

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and 10 per cent oxygen on the electrocardiogram in normal newborn infants ranging in age from birth to 9'days. Cardiac catheterization was not performed as a part of these investigations. I~IATERIALS A N D

1HETHODS

All of the newborn infants studied in this report were selected after history and physical examination had demonstrated that each was free from cardiovascular disease. No heart murmurs were recorded on the phonocardiogram. Group I consistad of 30 infants born in the University Hospital at Turku, Finland. Electrocardiograms were recorded daily for the first 3 to 4 days of life by use of the conventional techniques and leads recommended by Ziegler2 ~ Groups II and I I I were comprised of 25 infants each born in the SSdrabarnbordhuset, Stockholm, Sweden. The 25 infants of Group I I were under 24 hours of age and the 25 of Group I I I were between 5 and 9 days of age. This later age period was selected to compare with the former since it is thought that the major neonatal circulatory adjustments are completed by 5 days of age under normal circumstances2, G In these two groups of infants, the three standard biopolar, the three unipolar extremity, and unipolar Leads V~ and V~ were recorded in each. Group IV consisted of 10 infants under 24 hours of age. In each infant, a base-line electrocardiogram was obtained, as mentioned, for Groups I I and III. With the electrocardiogram recording unipolar Lead V~, five of the infants (Group IVa) were given 50 ttg of acetylcholine (2 intravenously

OF P E D I A T R I C S

and 3 intramuscularly) and a continuous recording was made for five minutes. In five other infants in this age period (Group IVb) 100 per cent oxygen was administered by a small hood for periods of 10 to 20 minutes during which time electrocardiographic tracings were periodically made of unipolar Lead VI. Group V consisted of 12 infants 5 to 10 days of age. As in Group IV, base-line electrocaTdiographic tracings were obtained in each. With the electrocardiogram recording unipolar Lead V1, six of the infants (Group Va) were given 50 ~g of adrenaline intramuscularly and a continuous recording was made for five minutes. In two infants, 97 and 93, a second dose of 100 ~g of adrenaline was given. and followed similarly; two others 95 and 96 received only 100 ~g of adrenaline. In four other infants (Group Vb) 10 per cent oxygen with 90 per cent nitrogen was administered by a small hood for 10 minutes during which time electrocardiographic tracing~ were periodically made of unipolar Lead V1. All of the electrocardiograms were taken with a direct writing apparatus of t h e " j e t " type (Elema Mingograph) using small electrodes. The concerttration of the gas mixtures entering the baby was checked in each case with a Beckman oxygen analyzer, the sampling tip of which was placed at the nostrils. Readings were made periodically during each study. Measurements of the electrocardiographic tracings were made according to the recommendations of Ziegler2 ~ RESULTS

Table I summarizes the pertinent results obtained in the longitudinal

D U P U I S E T AL. :

CARDIOVASCULAR S T A T U S OF N E W B O R N I N F A N T S .

studies of the t h i r t y infants in Group I ranging in age from birth to 4 days. Each infant with the age at the time of study is listed. There were 16 female infants and 14 male infants. All had normal weights and lengths. I n 19 of the 33 infants, the electrocardiographic axis deviation decreased with time, but these variations were frequently slight and of little significance. All showed evidence of right ventricular hypert r o p h y as manifest by prominent RV~ and SV~. The T wave in V~ was positive in all infants prior to 12 hours of age and positive in most up to 24 hours of age. A f t e r this time, TV~ frequently became diphasic and then negative. There appeared to be no relationship between TV~ and the axis deviation or RV1 and SVs. TV~ was usually positive, but it was negative on six occasions, including 3 times in infant No. 20. The ventricular activation time of V1 in all infants was 0.02 second or less. Table I I summarizes the pertinent results obtained in the cross-sectional studies of the 25 infants in Group I I ; all were under 24 hours of age. There were ]3 male and _12 female infants; all had normal weights and lengths. They are arranged according to increasing age, the youngest was _1 hour and the oldest was 24 hours. The mean axis deviation was _130 degrees with a range of _105 to _170 degrees. As in Group I, all showed evidence of right ventrieular h y p e r t r o p h y as manifested by a prominent RV~ and SVs. The T wave in V~ was positive in those infants under _12 hours of age. Between 12 and 24 hours of age there were 4 infants who had diphasie and 3 who had negative T waves in V~. Table I I I summarizes the pertinent results obtained in the cross-sectional

IV

651

studies of the 25 infants in Group III, all of whom were between 5 and 9 days of age. There were 16 male and 9 female infants; all had normal weights and lengths. They arc arranged according to increasing age ; the youngest was 5 days and the oldest was 9 days. The mean axis was 130 degrees with a range of 103 to 185 degrees. As in Groups I and II, all infants showed evidence of right ventrieular hypertrophy. The T wave in V~ was negative in 20 infants and slightly diphasic i n 5 infants. The major diphasic component in this later group was always negative. The results of the administration of 50 ~g of acetylcholine to five infants are summarized in Table IV. These infants ranged in age from 5 hours to 30 hours. In two, the drug was given intravenously and in three it was given intramuscularly in the arm. Although some inconsistent changes in the heart rate occurred, no other effects were observed on the electrocardiogram including the amplitude of the T wave in V~ which was positive in each case. The results of breathing 100 per cent oxygen obtained in five infants for ten to twenty minutes are summarized in Table V. These infants were between I hour and 25 hours of age. The heart rate frequently decreased slightly but not invariably. The T wave in V, was positive in all prior to, during, and following the procedure. The oxygen appeared to have no effect on it or any other part of the electrocardiogram. All of the babies appeared agitated and 3 infants vomited. Group V contained those infants 5 to 10 days of age. In six of these, 50 ~g of adrenaline was given intramuscularly, two of whom received a second

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CARDIOVASCULAR STATUS OF NEWBORN INFANTS. IV

injection of 100 t,g. The results of these studies are summarized in Table VI. Commonly there was an increase in heart rate of variable degree; however, a few showed bradycardia due to disturbances of rhythm. There were 2 instances of nodal rhythm, 3 of nodal extrasystoles, and 1 of bigeminal rhythm. In a]l instances, changes occurred in TV~, which prior to administration of adrenaline was negative. In one instance, it became positive and in the others it became diphasic. The infants responded by manifesting agitation and early suffusion followed by paleness and tachypnea. Ten per cent oxygen in 90 per cent nitrogen was administered by hood for 10 minutes to four infants of TABLE VII.

659

general agreement with the earlier reported findings of Ziegler22 Specifically the T wave in unipolar Lead V1 was regularly positive under 12 hours of age and negative or diphasic after 5 days of age. The transition between these two phases was gradual and took place over the same time interval that the pulmonary hypertension normally disappears2, 6 Evidence of right ven-~ tricular hypertrophy, however, persisted throughout this entire period without significant change. Administration of adrenaline to infants with presumably normal pulmonary artery pressures frequently produced changes in the T waves of the electrocardiogram similar to those found in infants with pulmonary hypertension.

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The results of these studies on the electrocardiographic changes with age in the normal newborn infant are in

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Earlier attempts by us to reduce the pulmonary hypertension in infants under 24 hours of age by administration of acetylcholine or breathing 100 per cent oxygen were unsuccessful2 The negative results in these electrocar~ diographic studies are consistent with the earlier observations. This lack of effect of acetylcholine on the pulmonary hypertension of newborn infants is in constrast to its effect in adults 14-16 and animals1~ n with pulmonary hypertension. The negative effect of 100

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T H E J O U R N A L OF PEDIATRICS

per cent oxygen in these infants is also in constrast to its effect in some adults with pulmonary hypertensionY The inability to alter significantly the electrocardiographic pattern of newborn infants by administration of either 10 per cent or 100 per cent oxygen speaks against acute anoxia or anoxemia as a common cause of the findings. ~s In spite of the results of these studies and of those reported previously, it is still difficult to make any positive statements regarding the nature of the pulmonary hypertension in the normal newborn infant. F u r t h e r studies are indicated. SUMMARY The e l e c t r o c a r d i o g r a p h i c changes i n the n o r m a l n e w b o r n i n f a n t d u r i n g the first 10 days of life were i n v e s t i g a t e d . T h i r t y i n f a n t s were s t u d i e d l o n g i t u d i n a l l y a n d seventy-two were s t u d i e d cross-sectionally. The physiologic response of c e r t a i n of the l a t t e r g r o u p of i n f a n t s to a d m i n i s t r a t i o n of 10 p e r cent a n d 100 p e r cent o x y g e n b y mask a n d to a d r e n a l i n e a n d acetylcholine was m e a s u r e d r e c o r d i n g u n i p o l a r L e a d Vl.

Changes with age reported earlier by Ziegler were confirmed. Alteration of the T wave in V1 took place over the same time interval that the pulmonary hypertension normally disappears. In older infants, administration of adrenaline produced changes in the T wave of V1 similar to those found in younger infants who normally have pulmonary hypertension. Administration of 100 per cent oxygen to the younger infants and 10 per cent oxygen to the older infants produced no significant alteration in the electrocardiographic tracing of V ,

other than Likewise, choline to duced no pattern.

minor changes in the rate. administration of acetylthe younger infants prosignificant change in the

REFERENCES 1. Prec, K. J., and Cassels, D. E.: Oximeter Studies in Newborn Infants During Crying, Pediatrics 9: 756, 1952. 2. Prec, K. J., and Cassels, D . E . : Dye Dilution Curves and Cardiac Output in Newborn Infants, Circulation 11: 789, 1955. 3. Lind, J., and Wegelius, C.: Human Fetal Circulation Changes in the Cardiovascular System at Birth and Disturbances in the Postnatal Closure of the Foramen Ovule and Ductus Arteriosus, Cold Spring Harbor Syrup. Quant. Biol. 19: 109, 1954. 4. Eldridge, F. L., ]/[ultgren, H. N., and Wigmore, IV[. E.: Physiologic Closure of the Ductus Arteriosus in Newborn Infants, Science 119: 731, 1954. 5. Adams, F. It., and Lind, J.: Physlologic Studies on the Cardiovascular Status of Normal Newborn Infants, Pediatrics 19: 431, 1957. 6. ]~owe, 1~. D., and James, L. S.: The Normal Pulmonary Arterial Pressures During the First Year of Life, J. PEDIAT. 5.1: 1, 1957. 7. Barclay, A. E , Franklin, K. J., and ]?richard, IV[. ~V[.J. : The Foetal Circulation, Springfield, Ill.~ 1945, Charles C Thomas. 8. Born, G. V. R., Dawes, G. S., Mott, J. C., and Rennick, B. R.: The Constriction of the Ductus Arteriosus Caused by Oxygen and by Asphyxia in Newborn Lambs, J. Physiol. 132: 304, 1956. 9. Adams, F. H., Lind, J., and Rauramo, L.: Physiologic Studies on the Cardiovascular Status of Normal Newborn Infants. III. Effect of Adrenaline, Noradrenaline, Acetylcholine, 10% Oxygen and 100% oxygen. To be published. 10. Adams, F. ~.~ Hirvonen, L., Lind, J., and Peltonen, T : Physiologic Studies on the Cardiovascular Status of Normal Newborn Pigs and Lambs. II. Effect of Adrenaline, Noradreualine, Acetylcholine, and Serotouin. To be published. 11. Dawes, G. S., ~r J. C., and Renuick, B.R.: Some Effects of Adrenaline, Noradrenaline and Acetylcholine on the Fetal Circulation in the Lamb, 5. Physiol. 134: 139, 1956. 12. Ziegler, R. F.: Electrocardiographic Studies in Normal Infants and Children, Springfield, Ill., 1951, Charles C Thomas. 13. James, L. S.: Personal communication. 14. Itarris, P.: Influence of Aeetylcholine on the Pulmonary Arterial Pressure, Brit. Heart J. 19: 272, 1957.

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CARDIOVASCULAR STATUS 01~ NEWBORN INFANTS, IV

15. Wood, P., Besterman, E. M., Towers, M. I(., and McIlroy, IV[. B.: The Effect of Acetylcholine on the P u l m o n a r y Yascular Resistance and the Left Arterial Pressure in lViitral Stenosis, Brit. H e a r t J. 19: 279, 1957. 16. Carmlchael, E. A., and Fraser, E. R.: The Effects of Acety]choline in Man, H e a r t 16: 262, 1933.

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17. MeGuire, J.~ Scott, 1%. C., Helm, R. A., Kaplan, S., Call, E. A., and Bichl, J. P. : Is There an E n t i t y P r i m a r y Pulmonary Hypertension~ Arch. Int. Med. 99: 917, 1957. 18. Southern, E. M.: F e t M Anoxia a n d Its Possible Relation to Changes in t h e Prenatal Fetal Electrocardiogram, Am. J. Obst. & Gynee. 73: 233, 1957.

Piece of Tin ~n the Windpipe. Laryngo-tracheotomy.--Dr. Paul F. Eve records (Nashville Journ. Med. and Sung., Sept., 1857) the ease of u negro boy, three years of age, which strongly illustrates the occasional great power of endurance of the human system. The patient two days before being taken to Dr. E., ~'whilc attempting to whistle with a small strip of tin in ltis mouth, fell backwards out of a piazza and inhaled it into his windpipe. This was followed by i n s t a n t and persistent embarrassment to respiration, loud rhonehus, loss of voice, or rather its reduction to a whisper, and some slight hemorrhage. The family physician not having relieved the patient by an emetic, inversion of the body, etc.," directed the boy to be taken to Nashville. Being satisfied from the symptoms t h a t tSere was a foreign body in the windpipe, Dr. E. decided to operate. Accordingly, on the 13th June, four days after the accident, Dr. E. opened the larynx, and then the trachea, and mado ' ' diligent search' ' for the foreign substance. The larynx was twice wiped out by sponges carried through the wound and brought out of the mouth, and the trachea and bronchi carefully and cautiously explored with probes and long forceps, but nothing special detected. There was an unusual amount of hemorrhage in the division of the soft parts, and ligatures were applied to each side of the isthmus of t h e thyroid body before its section. Dr. ]3owling administered the anaesthetic agent (equal portions of ether and chloroform), while Drs. Jennings, Briggs, Wharton and others aided during the operation, which to any one who has never opened the windpipe of a f a t child three years old, it would be unnecessary to say, was a tedious and embarrassing one. The second morning, during a paroxysm of cough, u piece of tin, measuring seventenths of an inch in length, and three-twentieths in width, with sharp angles and edges, was ejected through the wound. I t was smooth and polished upon its two suifaces, discolored, however, now by bloody mucus. Treatment, antlphlogistic, continued. I n a day or two the patient began to improve, and on the tenth day left for home.