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The electrocardiogram in normal newborn infants: Correlation with hemodynamic observations
578
7"he ] o u r n a l o/ P E D I A T R I C S
The electrocardiogra m in normal newborn infant; Correlation with hemodynamic observations The electrocardiograms o / 2 8 normal newborn in/ants aged l to 27 hours were correlated with pulmonary arterial pressure, presence o/left-to-right shunt through the ductus arteriosus, and pulmonary to systemic pressure ratio. The data indicate that postnatal hemodynamic changes are reflected in the electrocardiogram o / t h e normal newborn infant. Upright T-waves in the right precordial leads were associated with significantly higher pulmona,)' alterial pressure. The majority of in~ants with negati~:e T-waves in V~ were under 10 hours o/age and had Ie/t-to-right shunts through the ductus arteriosus. An R / S ratio less than 1 in the right precordial leads was observ'ed only in in/ants with le/t-to-right shunts through the duetus, while an R / S ratio o/ more than l in V~ war as.,ociated with a lower pulmonary-to-systemic pressure ratio. There was no correlation between the R or S waves in the precordial leads and the aboee hemodynamie parameters.
George C. Emmanouilides, M.D., Arthur J. Moss, M.D., and Forrest H. Adams, M.D. LOS
ANGELES
AND ' F O R R A N G E ~
CALIF.
THe: ELECTROCARDI(IGRAM of normal full-term infants is characterized by right axis deviation, a tendency to right ventricular preponderance, and certain T-wave changes in the precordial leads. 19 These characteristics are believed to be due partially to increased right ventricular mass and pressure.2, a, 6, s, 10, ~ In 1961, Keith and associates '~ reported that the electrocardiogram {n infants with From the Department o/Pediatrics, School of Medicine, University of Calilornia, Los Angeles, and Los Angeles County Harbor General Hospital, Torrance, Call/. Supported by grants from the United States Public Health Service.
the respiratory distress syndrome may reflect pulmonary hemodynamics. It was suggested by these authors that the presence of a high pulmonary vascular resistance may be associated with tall R waves in the right precordial leads, while a low resistance with a large left-to-right shunt via the ductus arteriosus may be associated with deep S waves. A direct correlation between the incidence of positive T waves in the right precordial leads and elevation of the right ventricular mean pressure was postulated by Ziegler5 a More recently, Hait and Gasu114 proposed that flat or negative T waves in the left precordial leads during the first few hours after
Volume 67 Number 4
Electrocardiogram in normal newborn
birth are probably the result of transient left ventricular "ischemia." As part of previously reported studies of postnatal cardiovascular adjustments, 1~-1s electrocardiograms were obtained and correlated with hemodynamic observations in 28 normal newborn infants. The results form the basis of the present report. SUBJECTS
AND
METHODS
Hemodynamic studies by way of the umbilical arteries were carried out on 28 normal full-term infants, aged 1 to 27 hours. The infants remained quiescent and in a relatively steady state throughout the procedure so anesthesia was not necessary. Pulmonary arterial, right ventricular, and systemic arterial pressures were recorded on a direct-writing multichannel recorder. Mean pressures were calculated by planimetry. Shunting through the ductus arteriosus was determined by cuvette oximetry. 15 Twelve-lead electrocardiograms, including the standard limb leads and unipolar precordial leads (V3R, V1, V2, V4, V~, V6), were recorded for each infant at the time of the hemodynamic studies. A Cambridge "Simpli-Scribe" electrocardiograph with infant electrodes was used. The paper speed was 25 rnm. per second and the sensitivity was 1 my. per 1 cm. deflection. In some instances, because of high amplitude of the Q R S complex, a more attenuated sensitivity was employed (1 my. per 0.5 cm. deflection). Heart rate, P-R interval, Q R S interval, Q - T interval, and the QRS axis in the frontal plane were determined. The P, Q, R, S, and T waves were measured to an accuracy of 0.5 mm. (1/20 my.). The electrocardiographic parameters were evaluated statistically and correlated with mean pulmonary arterial pressure, left-toright shunt through the ductus arteriosus, and the ratio of mean pulmonary to mean systemic pressure. RESULTS
Hemodynamic observations. Table I shows the age in hours, the pulmonary and systemic arterial pressures, the mean pulmonary to
5 79
systemic pressure ratio (PAP/ASP), and the incidence of left-to-right shunts. In 14 infants, evidence of a left-to-right shunt through the ductus arteriosus was found; all but one of these were under 13 hours of age. The calculated pulmonary to systemic flow ratio did not exceed 2:1 in any case. In the remaining 14 infants, the majority of whom were over 13 hours, no evidence of shunting was found. The mean pulmonary arterial pressure ranged from 22 to 52 mm. H g (average, 35.7 _+ 8.8), and the systemic pressure from 36 to 68 ram. Hg (average 56 + 7.7). The average mean pulmonary arterial pressure was 37.8 (+ 10.4) in babies under 13 hours of age and 33.3 (_+ 6.2) in those 13 to 27 hours of age. The difference was not statistically significant. The ratio of the mean pulmonary arterial and aortic pressure ranged from 0.45 to 0.91 (average, 0.63 _+0.12). H e a r t rate. The average heart rate was 134 per minute with a range of 114 to 162 beats per minute. There was no significant difference in the heart rate between infants with or without a shunt, nor a correlation between heart rate and mean pulmonary arterial or mean systemic pressure. P wave and P - R interval. The mean P-R interval of the entire group of infants was 0.105 second (range, 0.09 to 0.12 second). The height of the P wave in lead I I or V1 or V2 ranged from 1.0 to 2.5 ram., with an average of 1.85 ram. The taller P waves were more frequently observed in infants with a mean pulmonary arterial pressure of more than 30 ram. Hg. Fourteen of 19 infants with a mean pulmonary arterial pressure over 30 mm. Hg had P waves of 2 ram. or more, while only 3 of 9 infants with a pressure less than 30 mm. had P waves of 2 mm. or more. These differences were significant at the 5 per cent level. Q R S interval (measured in precordial lead V1 or V~). The duration of the QRS interval ranged from 0.04 to 0.08 second (average, 0.05). No significant difference was noted in the duration of the QRS interval between infants with or without left-toright shunts, nor was there a correlation be-
580
Emmanouilides
T a b l e I. H e m o d y n a m i c
Case No.
Age (hr.)
1
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
2 2 3 3 7 7 8 9 10 10 10 10 12 13 18 18 18 19 19 21 21 2l 23 24 24 25 27
Moss, and Adams
October 1965
o b s e r v a t i o n s i n 28 n o r m a l n e w b o r n i n f a n t s
Pressure (ram. Hg) Pulmonary artery S [ D I M 60 42 72 72 42 66 66 42 40 70 54 46 68 44 34 54 62 36 34 46 54 62 48 52 58 56 48 50
34 18 24 30 20 40 32 14 20 36 I6 16 36 18 14 20 24 16 10 20 20 24 12 16 22 16 16 18
45 29 47 47 29 52 45 27 33 50 33 29 50 29 22 37 44 27 '22 31 35 42 27 32 38 36 30 32
Aorta
IDIM
62 66 74 76 64 72 64 52 78 76 72 60 68 58 58 76 74 52 46 64 70 74 62 72 80 72 76 60
40 46 52 48 48 54 44 32 56 50 54 40 40 42 38 56 56 40 28 48 50 54 42 46 56 50 48 42
PXP/A6P
Qp/Qs
.88 .53 .76 .78 .53 .85 .83 .64 .51 .83 .53 .56 .91 .58 .45 .56 .65 .61 .61 .55 .58 .66 .54 .55 .57 .61 .47 .64
2.0 1.2 1.3 1.4 1.8 1.5 1.5 1.2 1.0 1.9 1.0 1.4 1.8 1.3 1.8 1.0 1.0 1.0 1.0 1.0 1.6 1.0 1.0 1.0 1.0 1.0 1.0 1.0
51 55 63 60 55 61 54 42 65 60 62 52 55 50 49 66 68 44 36 56 60 63 50 58 66 59 62 50
S, systolic.
P.KP/ASP, mean pulmonary to systemic pressure ratio.
D, diastolic. M, mean.
Qp/Qs, pulmonary to systemic flow ratio.
T a b l e I I . P e r c e n t of i n c i d e n c e of Q w a v e in 28 n o r m a l i n f a n t s in alI l e a d s
Number o[ in[ants
I
I II
I lII ] A V R I A VLI AVF I RV3 I V1 ] V~, I V,,
V.~ I V.
3.5
81
86
54
7
81
7
3.5
0
0
11
39
(with left-to-right shunt* )
7.0
71
71
50
14
70
(/
0.0
0
0
7
57
(without left-toright shunt* )
0.0
100
100
57
0
92
15
7.0
0
0
14
21
28 14 14
*Through the ductus artemosus.
t w e e n this i n t e r v a l a n d t h e level of t h e p u l m o n a r y a r t e r i a l pressure. Q-T interval (measured in standard lead I I ) . T h e r e was n o c o r r e l a t i o n b e t w e e n tlle Q - T i n t e r v a l ( a v e r a g e , 0.25 s e c o n d w i t h r a n g e , 0.22 to 0.30 s e c o n d ) a n d tile d e g r e e of p u l m o n a r y h y p e r t e n s i o n or t h e p r e s e n c e of a left-to-right shunt. S T .segment. I n 2 i n f a n t s , a s i g n i f i c a n t S T
segment depression was present m the right p r e c o r d i a l leads. B o t h i n f a n t s h a d a leftto-right shunt and a mean pulmonary arterial p r e s s u r e less t h a n 30 r a m . H / . Q R S axis. T h e Q R S axis in t h e f r o n t a l p l a n e was +149 d e g r e e s w i t h a r a n g e of 105 to 190 degrees. T h e m e a n axis of t h e i n f a n t s w i t h s h u n t w a s slightly l o w e r (145 d e g r e e s ) t h a n t h e m e a n axis o f t h o s e w i t h o u t s h u n t s
Volume 67 Number 4
Electrocardiogram in normal newborn
(153 degrees), but the difference was not statistically significant. Q wave. The incidence of a Q wave in the various leads is given in Table II. There was a higher incidence in precordial lead V6 in infants with a left-to-right shunt (8 out of 14) as opposed to those without a shunt (3 out of 14), but these differences were not statistically significant. T h e average mean pulmonary arterial pressure in the infants with a Q wave in V6 was 34.5 (_+ 9.4) ram. Hg, as opposed to the average pressure of the infants without a Q wave in V6 which was 36.5 (+ 8.6) ram. Hg. This difference was not statistically significant. R wave. T h e amplitude of the R and S waves, the R / S ratio in the precordial leads, the mean pulmonary arterial pressure, and the pulmonary to systemic pressure ratio are presented in Table I I I . T h e mean values of these measurements as well as the standard deviation are also given. T h e mean values of R and S wave amplitude in the limb leads are given in Table IV. There was no correlation between the height of the R wave and the mean pulmonary arterial pressure, the presence or absence of left-to-right shunts, or the pulmonary to systemic mean pressure ratio (Fig. 1). Only 2 infants had R waves in Vz more than 24 mm.
S wave. No significant correlation between the depth of the S wave and the mean pulmonary arterial pressure or the pulmonary to systemic pressure ratio was found (Table I I I ) . In the group of babies with a shunt, the mean S wave was slightly higher in leads VI, V~, and V4 and somewhat lower in V6 (Fig. 1). R / S ratio. T h e median, minimum, and m a x i m u m values of the R / S ratio in the precordial leads are listed in Table I I I . There was no significant correlation of this ratio with the mean pulmonary arterial pressure, the presence of left-to-right shunt, or the pulmonary to systemic pressure ratio. T h e R / S ratio in one or more of the right precordial leads was less than 1 in 3 infants, and in all 3, a left-to-right shunt was present. T h e R / S ratio in the left precordial leads was greater than 1 in 6 of the 28 infants (22 per cent), and, in 5 of these, a leftto-right shunt was present. T wave. Correlation of T-wave deflection and the mean pulmonary arterial pressure is shown in Table V and Fig. 2. There was a significant correlation (P ~ 0.01) between negative T waves in RV3 or Vz and the mean pulmonary arterial pressure. Infants with a negative T wave in these leads had a lower pulmonary arterial pressure than did infants with an upright T wave, who had sig-
S WAVE in 28 normal newborn infanfs
R WAVE in 28 normal newborn infants
o---o Infonfs wifh L-~Rf shunf (14) 9 9 I n f o n f s w i f h o u f L - > R f s h u n f (14)
25
25-
~o
20.
oSS
1 5 84
mm
(140mV) I0-
~III
~
0
i
i
~
10-
'o
5"
5-
58 1
0
i
Fig. 1. Mean S and R waves in precordial leads of 14 infants with left-to-right ductal shunts and 14 infants with no ductal shunts. The small differences between the 2 groups are not statistically significant.
582
Emrnanouilides,
October 1965
Moss, and Adams
T a b l e I I I . R a n d S w a v e a m p l i t u d e a n d R / S ratio in p r e c o r d i a l leads of 28 n o r m a l n e w b o r n infants Case No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 2O 21 22 23 24 25 26 27 28
Meant and S.D.
V,,R
R
I
V,
s
R/S
10.0 6.0 5.0 6.0 10.0 9.0 6.0 15.0 7.0 12.0 17.0 13.0 16.0 12.0 7.0 12.5 8.0 13.0 5.5 9.0 8.0 13.0 5,0 15.0 10.0 11.0 20.0 16.0
4.0 1,5 3.5 1.0 9.0 6.0 1.0 1.5 1.5 5.0 1.5 5.(1 2.0 ---2.5 2.0 1.0 -3.0 16.(I 1.5 0.5 2.0 3.O 0.5 1.0 4.0
2.5 4.0 1.4 6.0 1.1 1.5 6.0 10.0 5.0 2.4 11.0 2.6 8.0
3.0 0.5 9.0 25.0 7.5 3.3 22.0 20.0 4.0
10.6
2.8
6.0
+4.0
3.3
5.0 4.0 13.0 ~o
(1.4-32.0)
R
S
V,
R/S
21 11 15 22 17 10 13 20 15 20 26 11 23 15 9 20 10 20 8 13 10
12.0 4.0 12.0 28.0 17.0 5.0 5.0 3.0 9.0 11.0 14.0 4.0 8.0 0.5 16.0 4.0 5.0 1.0 7.0 15.0
45.00 1.25 2.50 4.00 8.00 1.90 0.66
18
4.5
4.00
8 23 17 16 25 20
3.0 6.0 6.0 2.0 2.0 12.0
2.70 3.80 2.9O 8.00 12.50 1.70
16.2
7.7
5.3
6.3
1.70
R
I
s
20 21 15 21 22 18 26 26 18 28 24 17 15 7 13 22 12 22 8 12 16 2t 16 36 24 16 15 10
26 17 25 32 42 21 24 18 18 26 22 11 20 5 17 30 17 20 19 22 26 7 23 21 20 15 23 11
2.5
18.6
20.6
(0.66-18.0)
6.4
7.4
2.20 1.20
0.79 1.00
2.00 2.60 6.60 1.70 1.80 1.80
2.70 3.00
I
R/S
0.70 1.20
0.60 0.63 0.48 0.89 I.I0 1.40 1.00
1.10 1.10 1.50
0.75 1.40
0.77 1.25
0.70 1.10 0.42 0.54 0.61 3.00 0.70 1.40 1.20
1.10 0.66 0.90 1.0 (0.42-3.0)
*Infants with left-to-right shunt through the ductus arteriosus "~For R / S ratios, the median was given with the m i n i m u m and maximum values in parentheses.
T a b l e I V . M e a n (+_ S.D.) R a n d S w a v e a m p l i t u d e in m i l l i m e t e r s (1//10 m v . ) in limb leads Lead
R wave (Mean +- S.D.)
I II III AVR*
1.6 4.8 8.7 4.7
+ + + +
1.3 3.2 3.0 2.5
AVL AVF
1.5 + 1.0 6.2 + 3.6
S wave (Mean +- S.D.)
6.8 3.2 0.25 9.8 (1.0) 7.2 1.3
+ + + +
2.9 2.7 0.75 1.1 (1.3) + 2.6 + 1.4
"~S waves were present in only 13 cases. Q waves were present in 14 eases (in parentheses) and in one case an r R complex was present.
nificantly h i g h e r pressure. H o w e v e r , it is imp o r t a n t to recognize t h a t some o v e r l a p p i n g was observed, a n d because of the small n u m b e r of infants w i t h n e g a t i v e T w a v e s in these leads, the c a l c u l a t e d statistical significance
m a y n o t a p p l y to i n d i v i d u a l cases. T h e a v e r age p u l m o n a r y arterial pressure of infants w i t h d i p h a s i c T w a v e s in the s a m e leads ( V a R a n d V1) was g r e a t e r t h a n t h a t of infants w i t h n e g a t i v e T waves, b u t less t h a n t h a t of infants w i t h u p r i g h t T waves. T h e s e differences, h o w e v e r , w e r e n o t statistically significant ( T a b l e V ) . E i g h t y - n i n e per c e n t of the infants h a d u p r i g h t or diphasic T waves in V~, a s o m e w h a t h i g h e r i n c i d e n c e t h a n t h a t o b s e r v e d by K e i t h a n d c o - w o r k e r s ? 2 All 3 infants w i t h n e g a t i v e T w a v e s in this series w e r e older t h a n 10 hours of age, a n d , in 2, an associated depression of the S T segm e n t was present. T h e r e was some c o r r e l a tion (p < 0.05) b e t w e e n the i n c i d e n c e of a n e g a t i v e T w a v e in V6 a n d the level of p u l m o n a r y arterial pressure. T h e infants w h o s h o w e d n e g a t i v e or flat T w a v e s in V~ h a d
Volume 67 Number 4
Electrocardiogram in normal newborn
V~
.
I sq
16 19 18 14 18 10 28 22 15 2O 20 18 i1 8 10 16 13 24 9 11 15 17 13 26 22 20 18 15
26 24 30 24 42 24 26 20 16 26 34 13 21 13 12 22 20 20 19 27 30 9 26 22 30 15 14 20
16.6
22.3
5.1
7.3
V5
RI
R/S 0.65 0.80 0.60 0.58 0.43 0.42 1.30 1.10 0.93 0.78 0.59 1.40 0.48 0.80 0.83 O.72 0.65 1.20 0.45 0.41 O.5O 1.90 0.50 1.20 O.75 1.30 1.28 O.75
15 13 10 6 7 9 18 9 11 11 13 I0 6 5 8 13 9 13 6 4 10 12 9 17 12 17 10 13
V6
s
R/S 0.65 1.30 0.50 0.43 0.25 0.49 1.00 0.60 0.68 0.64 0.45 0.90 0.37 0.38 1.00 1.90 0.56 0.72 0.60 0.30 0.44 1.00 0.60 0.85 0.43 1.I0 0.60 0.85
22 10 20 14 28 20 18 15 16 17 28 11 16 13 8 7 16 16 10 12 22 12 15 20 26 16 17 15
583
Mean
R/S
PAP
4.0 8.0 10.0 4.0 3.0 4.0 10.0 3.0 4.0 2.0 9.0 3.0 3.0 3.0 5.0 13.0 2.5 7.0 5.0 2.5 4.0 4.0 8.0 7.0 7.0 8.0 5.0 7.0
7.0 3.0 12.0 6.0 14.0 9.0 9.0 7.0 9.0 7.O 16.0 2.5 9.0 11.0 4.0 1.0 7.5 10.0 10.0 7.5 2.0 4.5 10.0 11.0 17.0 15.0 11.0 8.0
0.55 2.60 0.90 0.66 0.21 0.44 1.10 0.43 0.44 O.28 0.56 1.20 0.30 0.27 1.25 13.00 0.30 0.70 0.50 0.30 2.00 0.90 0.80 0.68 0.41 0.53 0.45 0.87
45* 29* 47* 47* 29* 52* 45* 27* 33 58* 33 29* 50* 29* 22* 37 44 27 22 31 35* 42 27 32 38 36 30 32
0.88 0.53 0.76 0.78 0.53 0.85 0.83 0.64 0.51 0.83 0.53 0.56 0.91 0.58 0.45 0.56 0.65 0.61 0.61 0.55 0.58 0.66 0.54 0.55 0.57 0.61 0.47 0.64
0.55
39.5
0.67
9.1
0.14
0.72
10.5
16.4
0.6
5.5
8.5
(0.4-1.9)
3.6
5.4
(0.23-1.9)
2.8
4.1
(0.21-12.0)
60-
40-
PAP rnrn,Hg 3020-
I0-
O-
Upright
1
Diphasic Necjative
VI
DiphasicNegative or Flat
Upright VS
Fig. 2. Correlation between T waves in VI and VG and mean pulmonary arterial pressure (PAP) in 28 normal newborn infants. Note that infants with negative T waves in V1 have lower mean pulmonary arterial pressure than those with positive T waves (p < 0.01). Negative T waves in V6 were associated with higher mean pulmonary arterial pressures than positive T waves (p < 0.05). The majority of infants with negative T waves in Ve had a left-toright shunt through the ductus arteriosus.
Emmanouilid~%
584
Moss, and A d a m s
T a b l e V. Correlation of T wave direction a n d m e a n p u l m o n a r y arterial pressure in 28 n o r m a l n e w b o r n infants
T Wave +
I
II
n 26
-
'2
•
0
+ -
28 0
I PAP I (mm. Hg) 35.0 41.0
PdP/ AOP .63 .71
36.0 .63 . . . .
-+
0
III
+ •
25 2 I
36.0 34.0 22.0
.65 .52 .45
AVR
+ -+
3 24 1
40.0 360 22.0
.68 .63 .61
AVL
+ •
'2'2 4 2
36.0 36.0 29.0
.64 .63 .58
AVF
+
28
36.0
.63
V:,R
+ +_
14 ') 1'2
40.0 26.0 33.0
.68 .51 .60
+
16
.65 .52 .63
V,
-
3
•
9
38.0 28.1) 34.0
V~
+ -
17 5 6
37.0 36.0 32.0
.65 .66 .56
V~
+ +
13 8 7
35 0 40.0 32.0
.62 .69 .58
+
18
,61 .71 .63 .61 .74 .55
V~
-+
4
33.0 41.0 38.0
+ +
22 5 1
34.0 43.0 32.0
-
Vo
6
PAP, mean puhnonary arterial pressme. PYtP/ASP, puhnonary to systemic pressure ratio. +, upright T wave. -,
negative T wave.
-+, diphaslc T wave.
higher p u l m o n a r y arterial pressures. No significant correlation was found between the presence or absence of a shunt a n d the direction of the T wave in V1. W h e n pulm o n a r y to systemic pressure ratio was related with T-wave direction, there was a correlation (p < 0.05) only for lead RV.~ and V~ b u t not for V6.
October 1965
DISCUSSION I n the present study, a correlation was made between various electrocardiographic measurements a n d the h e m o d y n a m i c findings in 28 normal full-term infants from 1 to 27 hours old. M e a n p u l m o n a r y arterial pressure, p u l m o n a r y to systemic pressure ratio, and presence or absence of a left-to-right shunt through the duetus arteriosus were correlated with electrocardiographic p a r a m eters. T h e results indicate that the electrocardiogram reflects the hemodynamics in the normal newborn. Keith a n d collaborators ~ reported hemodynamic observations in 2 n e w b o r n infants with respiratory distress syndrome. O n the basis of these observations, they described 2 types of electrocardiographic patterns based on the R / S ratio a n d the depth of the S wave in the right precordial leads. They postulated that infants with an R / S ratio less than 1 or with a deep S wave in V~ or V,_, have a large left-to-right shunt through the ductus arteriosus and a relatively lower pulm o n a r y vascular resistance, while infants with a ratio of more than 1 or tall R waves in VI a n d V2 have a smaller left-to-right shunt a n d a higher p u l m o n a r y vascular resistance. T h e same authors analyzed a n u m ber of electrocardiograms of infants with respiratory distress syndrome a n d f o u n d that a better prognosis was associated with the latter electrocardiographic patterns ( R / S > 1 a n d tall R waves in V1 a n d V2). I n the present investigation, a positive correlation could not be demonstrated between the R or S waves, the R / S ratios a n d the m e a n p u l m o n a r y arterial pressure, or the p u l m o n a r y to systemic pressure ratio. Walsh s found that babies u n d e r 1 hour of age had significantly higher R waves in the right precordial leads a n d deeper S waves in the left precordial leads t h a n infants beyond that age. T h e m e a n p u l m o n a r y arterial pressure during the first hour of life is equal to or higher t h a n systemic pressure, a n d a rlght-toleft s h u n t through the ductus arteriosus is usually present? s, ~7 This agrees with the studies conducted by Walsh. s Beyond 1 hour of age the p u l m o n a r y ar-
Volume 67 Number 4
terial pressure falls and by the end of the first day decreases to approximately 50 per cent of the systemic pressure level? 8 The right-to-left shunt is eventually replaced by a left-to-right shunt?~, as-2z, 27 A hemodynamically significant left-to-right shunt is generally present only in infants less than 15 hours of age? ~' 18, s0 The mean values of S waves in RV3, Va, and V2 of infants with a left-to-right shunt in the present study were slightly higher than those of infants without a detectable shunt (Fig. 1). However, these differences were not statistically significant. The discrepancy between these findings in normal infants and those of Keith 12 in infants with the respiratory distress syndrome may be due to larger shunts known to be present in this syndrome. In 3 infants of the present study, the R / S ratio in V1 was equal to or less than 1, and all 3 had a left-to-right shunt through the ductus arteriosus. This observation suggests the possibility that during the first 24 hours of life an R / S ratio in V1 of less than 1 may be associated with "left ventricular" loading due to a left-to-rlght shunt via the ductus arteriosus. A higher incidence of Q waves in V6 was observed in babies with shunts, although the difference was not statistically significant. All 3 cases with an R / S ratio in V1 equal to or less than 1 had Q waves in V6. In 6 instances, the R / S ratio in V6 was more than 1 and a left-to-right shunt was present in 5 of these. In the 4 infants of this group who were under 13 hours of age, the average pulmonary to systemic pressure ratio was 0.51 with a range of 0.45 to 0.56. In the infants under 13 hours of age with an R / S ratio in V6 less than l, the average pressure ratio was higher (0.73, range 0.53 to 0.91). This is in agreement with the observed gradual increase in the R / S ratio in V6 with increasing age, presumably related to increasing "left ventricular preponderance. ''2, 3, 8, 28, 29, 30 However, no anatomical changes are known to occur during the first 24 hours that could account for this change. TM The "left preponderance" must be a reflection of the drop in right ventricular pressure resulting
Electrocardiogram in normal newborn
58 5
from the reduction of pulmonary vascular resistance. Another contributing factor may be the load placed upon the left ventricle by an increase in peripheral vascular resistance occurring after removal from the placental circulation and by the left-to-right shunt which is present during the first day of life. The results of this study also indicate a positive correlation between the direction of T waves in the right precordial leads and the degree of pulmonary hypertension (Table V and Fig. 2). This observation confirms the hypothesis proposed by several authors that pulmonary hypertension may be the cause of the upright T wave in the right precordial leads in the first and second day after birth?a, 1~, ~2, 32, a3 The negative T waves in the left precordial leads during the first day of life have been interpreted as evidence of "left ventricular loading. ''14, 22 However, in this study, a correlation of negative T waves in the left precordial leads and the degree of pulmonary hypertension was found. In 6 infants in whom a flat or negative T wave was observed, a higher mean pulmonary arterial pressure was present (Table V). Five of these infants were under 13 hours of age and 4 had a left-to-right shunt. This high incidence of negative T waves may be related to the left-to-right shunt characteristically observed in this age group. 15' is, 2o Overloading of the left ventricle may well occur as a result of flow through the ductus arteriosus into a restricted pulmonary vascular bed. Although the height of P waves did not reach accepted abnormal values (more than 2.5 m m . ) , the data indicate that a P wave of 2 mm. or more in leads II, V1, or Vz was associated with a mean pulmonary arterial pressure greater than 30 mm. Hg. This observation that taller P waves occurred in infants with higher mean pulmonary arterial pressure may indicate some degree of atrial dilatation associated with right ventricular hypertension. SUMMARY
The electrocardiogram and hemodynamic data were correlated in 28 normal newborn
5 8 6 Emmanouilides, Most, and Adams
infants aged 1 to 27 hours. T h e data indicate that hemodynamic changes occurring after birth are reflected in the electrocardiogram of the n o r m a l newborn infant. 1. A significant correlation between the m e a n p u l m o n a r y arterial pressure a n d the T-wave deflection in V:d~, and V1 was found. I n f a n t s with upright T waves in these leads tend to have higher p u l m o n a r y arterial pressures than those with negative T waves (p < 0.01). 2. Infants with negative T waves in V,; also had higher p u l m o n a r y arterial pressures than those with upright T waves (p < 0.05). T h e majority of these infants were u n d e r 10 hours of age a n d had a left-to-right shunt via the ductus arteriosus. 3. All infants with an R / S ratio of less t h a n 1 in the right precordial leads had a left-to-right shunt. 4. A n R / S ratio in V,; of more than 1 was associated with a lower p u l m o n a r y to systemic pressure ratio. 5. No significant correlation was found between R a n d S waves in the precordial leads and the p u l m o n a r y arterial pressure, the presence of left-to-right shunts through the ductus arteriosus, or the p u l m o n a r y to systemic pressure ratio. REFERENCES
1. Ziegler, R. F.: Characteristics of the unipolar precordial electrocardiogram in normal infants, Circulation 3: 438, 1951. 2. Ziegler, R. F.: Electrocardiographic studies in normal infants and children, Springfield, Ill., 1951, Charles C Thomas, Publisher. 3. Sodi-Pollares, D., Portillo, B., Cisneros, F., De La Cruz, M. V., and Acosta, A. R.: Electrocardiography in infants and children, Pediat. Clin. North America 5: 871, 1958. 4. Micha~lsson, M.: Electrocardiographic studies in the healthy newborn, Acta paediat. 48, Suppl. 117: 108, 1959. 5. Datey, K. K., and Bharucha, P. E.: Electrocardiographic changes in the first week of life, Brit. Heart J. 22: 175, 1960. 6. Rothfeld, E. L., Wachtel, F. W., Karlen, W. S., and Bernstein, A.: The evolution of the vectorcardiogram and electrocardiogram of the normal infant: I. The normal newborn, Am. J. Cardiol. 5: 439, 1960. 7. DePasquale, N. P., and Burch, G. E.: The electrocardiogram, ventricular gradient, and spatial vectorcardiogram during the first week of life, Am. J. CardioI. 12: 482, 1963.
October 1965
8. Walsh, Z. S.: The electrocardiogram during the first week of life, Brit. Heart J. 25: 784, 1963. 9. Craige, E., and Harned, H. S.: Phonocardiographic and electrocardiographic studies in normal newborn infants, Am. Heart J. 65: 180, 1963. 10. Keen, E. N.: The postnatal development of the human cardiac ventricles, J. Anat. 89: 484, 1955. 11. Penaloza, D., Gamboa, R., Dyer, J., Echevarria, M., and Marticorena, E.: The influence of high altitudes on the electrical activity of the heart. I. Electrocardiographic and vectorcardiographic observations in the newborn, infants, and children, Am. Heart J. 59: 111, 1960. 12. Keith, J. D., Rose, V., Braudo, M., and Rowe, R. D.: The electrocardiogram in the respiratory distress syndrome and related cardiovascular dynamics, J. PEDIAT. 59: t67, 1961. 13. Ziegler, R. F.: The importance of positive T waves in the right precordial electrocardiogram during the first year of life, Am. Heart J. 52: 533, 1956. 14. Halt, G., and Gasul, B. M.: The evolution and significance of T wave changes in the normal newborn during the first seven days of life, Am. J. Cardiol. 12: 494, 1963. 15. Moss, A. J., Emmanouilides, G., and Duffle, E. R., Jr.: Closure of the ductus arteriosus in the newborn infant, Pediatrics 32: 25, 1963. 16. Moss, A. J., Duffle, E. R., Jr., and Emmanouilides, G. C.: Blood pressure and vasomotor reflexes in the newborn infant, Pediatrics, 32: I75, 1963. 17. Moss, A. J., Emmanouilides, G. C., Adams, F. H., and Chuang, K.: Response of ductus arteriosus and pulmonary and systemic arterial pressure to changes in oxygen environment in newborn infants, Pediatrics 33: 937, 1964. 18. Emmanouilides, G. C., Moss, A. J., Duffle, E. R., Jr., and Adams, F. H.: Pulmonary arterial pressure changes in human newborn infants from birth to three days of age, J. PEDIAT. 65: 327, 1964. 19. Adams, F. H., and Lind, J.: Physiologic studies on the cardiovascular status of normal infants (with special reference to the ducms arteriosus), Pediatrics 19: 431, 1957. 20. Rudolph, A. M., et al.: Studies on the circulation in the neonatal period. The circulation in the respiratory distress syndrome, Pediatrics 27: 551, 196l. 21. Rowe, R. D., and James, L. S.: The normal pulmonary arterial pressure during the first year of life, J. PEDIAT.51: I, 1957. 22. Castellanos, A., Jr., Lemberg, L., and Castellanos, A.: The vectorcardiographie significance of upright T waves in V, and V2 during the first months of life, J. PEmAT. 62: 827, 1963. 23. Cosby, R. S., Levinson, D. C., Zinn. W. J., Dimltroff, S. D., and Griffith, G. C.: Congenital heart disease: An analysis of electro-
Volume 67 Number 4
24.
25. 26. 27.
cardiographic patterns in forty-four patients with elevated right ventricular pressure, Am. Heart J. 44: 581, 1952. Goodwin, J. F.: The electrocardiogram in normal children and in children with right ventricular hypertrophy, Brit. Heart J. 14: 173, 1952. Hollman, A.: Electrocardiographic diagnosis of right ventricular hypertrophy in infancy and childhood, Brit. Heart J. 20" 129, 1958. Vince, D., and Keith, J. D.: The electrocardiogram in ventricular septal defect, Circulation 23: 225, 1961. Saling, E.: Neue Untersuchungergebnisse fiber den Kreislauf des Kindes unmittelbar naeh der Geburt, Arch. Gyn~ik. 194: 287, 1960.
28. Rothfeld, E. L., Wachtel, F. W., Karlen, W. S., and Bernstein, A.: The evaluation of the
Electrocardiogram in normal newborn
29. 30.
31. 32. 33.
587
vectorcardiogram and electrocardiogram in the normal infant. II. Transition toward adult patterns, Am. J. Cardiol. 5: 450, 1960. Scott, O., and Franklin, D.: The electrocardiogram in the normal infant, Brit. Heart J. 25: 441, 1963. Lucas, R. V., Jr., St. Geme, J. W., Jr., Anderson, R. C., Adams, P., Jr., and Ferguson, D. J.: Maturation of the pulmonary vascular bed. A physiologic and anatomic correlation in infants and children, Am. J. Dis. Child. 101: 467, 1961. Dawes, G. S.: Changes in the circulation at birth, Brit. M. Bull. 17: 148, 1961. Stern, L., and Lind, J.: Neonatal T-wave patterns, Acta paediat. 49" 329, 1960. Walsh, S. Z.: The S-T segment and T-wave during the first week of life, Brit. Heart J. 26: 679, 1964.
7"he ] o u r n a l o/ P E D I A T R I C S
The electrocardiogra m in normal newborn infant; Correlation with hemodynamic observations The electrocardiograms o / 2 8 normal newborn in/ants aged l to 27 hours were correlated with pulmonary arterial pressure, presence o/left-to-right shunt through the ductus arteriosus, and pulmonary to systemic pressure ratio. The data indicate that postnatal hemodynamic changes are reflected in the electrocardiogram o / t h e normal newborn infant. Upright T-waves in the right precordial leads were associated with significantly higher pulmona,)' alterial pressure. The majority of in~ants with negati~:e T-waves in V~ were under 10 hours o/age and had Ie/t-to-right shunts through the ductus arteriosus. An R / S ratio less than 1 in the right precordial leads was observ'ed only in in/ants with le/t-to-right shunts through the duetus, while an R / S ratio o/ more than l in V~ war as.,ociated with a lower pulmonary-to-systemic pressure ratio. There was no correlation between the R or S waves in the precordial leads and the aboee hemodynamie parameters.
George C. Emmanouilides, M.D., Arthur J. Moss, M.D., and Forrest H. Adams, M.D. LOS
ANGELES
AND ' F O R R A N G E ~
CALIF.
THe: ELECTROCARDI(IGRAM of normal full-term infants is characterized by right axis deviation, a tendency to right ventricular preponderance, and certain T-wave changes in the precordial leads. 19 These characteristics are believed to be due partially to increased right ventricular mass and pressure.2, a, 6, s, 10, ~ In 1961, Keith and associates '~ reported that the electrocardiogram {n infants with From the Department o/Pediatrics, School of Medicine, University of Calilornia, Los Angeles, and Los Angeles County Harbor General Hospital, Torrance, Call/. Supported by grants from the United States Public Health Service.
the respiratory distress syndrome may reflect pulmonary hemodynamics. It was suggested by these authors that the presence of a high pulmonary vascular resistance may be associated with tall R waves in the right precordial leads, while a low resistance with a large left-to-right shunt via the ductus arteriosus may be associated with deep S waves. A direct correlation between the incidence of positive T waves in the right precordial leads and elevation of the right ventricular mean pressure was postulated by Ziegler5 a More recently, Hait and Gasu114 proposed that flat or negative T waves in the left precordial leads during the first few hours after
Volume 67 Number 4
Electrocardiogram in normal newborn
birth are probably the result of transient left ventricular "ischemia." As part of previously reported studies of postnatal cardiovascular adjustments, 1~-1s electrocardiograms were obtained and correlated with hemodynamic observations in 28 normal newborn infants. The results form the basis of the present report. SUBJECTS
AND
METHODS
Hemodynamic studies by way of the umbilical arteries were carried out on 28 normal full-term infants, aged 1 to 27 hours. The infants remained quiescent and in a relatively steady state throughout the procedure so anesthesia was not necessary. Pulmonary arterial, right ventricular, and systemic arterial pressures were recorded on a direct-writing multichannel recorder. Mean pressures were calculated by planimetry. Shunting through the ductus arteriosus was determined by cuvette oximetry. 15 Twelve-lead electrocardiograms, including the standard limb leads and unipolar precordial leads (V3R, V1, V2, V4, V~, V6), were recorded for each infant at the time of the hemodynamic studies. A Cambridge "Simpli-Scribe" electrocardiograph with infant electrodes was used. The paper speed was 25 rnm. per second and the sensitivity was 1 my. per 1 cm. deflection. In some instances, because of high amplitude of the Q R S complex, a more attenuated sensitivity was employed (1 my. per 0.5 cm. deflection). Heart rate, P-R interval, Q R S interval, Q - T interval, and the QRS axis in the frontal plane were determined. The P, Q, R, S, and T waves were measured to an accuracy of 0.5 mm. (1/20 my.). The electrocardiographic parameters were evaluated statistically and correlated with mean pulmonary arterial pressure, left-toright shunt through the ductus arteriosus, and the ratio of mean pulmonary to mean systemic pressure. RESULTS
Hemodynamic observations. Table I shows the age in hours, the pulmonary and systemic arterial pressures, the mean pulmonary to
5 79
systemic pressure ratio (PAP/ASP), and the incidence of left-to-right shunts. In 14 infants, evidence of a left-to-right shunt through the ductus arteriosus was found; all but one of these were under 13 hours of age. The calculated pulmonary to systemic flow ratio did not exceed 2:1 in any case. In the remaining 14 infants, the majority of whom were over 13 hours, no evidence of shunting was found. The mean pulmonary arterial pressure ranged from 22 to 52 mm. H g (average, 35.7 _+ 8.8), and the systemic pressure from 36 to 68 ram. Hg (average 56 + 7.7). The average mean pulmonary arterial pressure was 37.8 (+ 10.4) in babies under 13 hours of age and 33.3 (_+ 6.2) in those 13 to 27 hours of age. The difference was not statistically significant. The ratio of the mean pulmonary arterial and aortic pressure ranged from 0.45 to 0.91 (average, 0.63 _+0.12). H e a r t rate. The average heart rate was 134 per minute with a range of 114 to 162 beats per minute. There was no significant difference in the heart rate between infants with or without a shunt, nor a correlation between heart rate and mean pulmonary arterial or mean systemic pressure. P wave and P - R interval. The mean P-R interval of the entire group of infants was 0.105 second (range, 0.09 to 0.12 second). The height of the P wave in lead I I or V1 or V2 ranged from 1.0 to 2.5 ram., with an average of 1.85 ram. The taller P waves were more frequently observed in infants with a mean pulmonary arterial pressure of more than 30 ram. Hg. Fourteen of 19 infants with a mean pulmonary arterial pressure over 30 mm. Hg had P waves of 2 ram. or more, while only 3 of 9 infants with a pressure less than 30 mm. had P waves of 2 mm. or more. These differences were significant at the 5 per cent level. Q R S interval (measured in precordial lead V1 or V~). The duration of the QRS interval ranged from 0.04 to 0.08 second (average, 0.05). No significant difference was noted in the duration of the QRS interval between infants with or without left-toright shunts, nor was there a correlation be-
580
Emmanouilides
T a b l e I. H e m o d y n a m i c
Case No.
Age (hr.)
1
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
2 2 3 3 7 7 8 9 10 10 10 10 12 13 18 18 18 19 19 21 21 2l 23 24 24 25 27
Moss, and Adams
October 1965
o b s e r v a t i o n s i n 28 n o r m a l n e w b o r n i n f a n t s
Pressure (ram. Hg) Pulmonary artery S [ D I M 60 42 72 72 42 66 66 42 40 70 54 46 68 44 34 54 62 36 34 46 54 62 48 52 58 56 48 50
34 18 24 30 20 40 32 14 20 36 I6 16 36 18 14 20 24 16 10 20 20 24 12 16 22 16 16 18
45 29 47 47 29 52 45 27 33 50 33 29 50 29 22 37 44 27 '22 31 35 42 27 32 38 36 30 32
Aorta
IDIM
62 66 74 76 64 72 64 52 78 76 72 60 68 58 58 76 74 52 46 64 70 74 62 72 80 72 76 60
40 46 52 48 48 54 44 32 56 50 54 40 40 42 38 56 56 40 28 48 50 54 42 46 56 50 48 42
PXP/A6P
Qp/Qs
.88 .53 .76 .78 .53 .85 .83 .64 .51 .83 .53 .56 .91 .58 .45 .56 .65 .61 .61 .55 .58 .66 .54 .55 .57 .61 .47 .64
2.0 1.2 1.3 1.4 1.8 1.5 1.5 1.2 1.0 1.9 1.0 1.4 1.8 1.3 1.8 1.0 1.0 1.0 1.0 1.0 1.6 1.0 1.0 1.0 1.0 1.0 1.0 1.0
51 55 63 60 55 61 54 42 65 60 62 52 55 50 49 66 68 44 36 56 60 63 50 58 66 59 62 50
S, systolic.
P.KP/ASP, mean pulmonary to systemic pressure ratio.
D, diastolic. M, mean.
Qp/Qs, pulmonary to systemic flow ratio.
T a b l e I I . P e r c e n t of i n c i d e n c e of Q w a v e in 28 n o r m a l i n f a n t s in alI l e a d s
Number o[ in[ants
I
I II
I lII ] A V R I A VLI AVF I RV3 I V1 ] V~, I V,,
V.~ I V.
3.5
81
86
54
7
81
7
3.5
0
0
11
39
(with left-to-right shunt* )
7.0
71
71
50
14
70
(/
0.0
0
0
7
57
(without left-toright shunt* )
0.0
100
100
57
0
92
15
7.0
0
0
14
21
28 14 14
*Through the ductus artemosus.
t w e e n this i n t e r v a l a n d t h e level of t h e p u l m o n a r y a r t e r i a l pressure. Q-T interval (measured in standard lead I I ) . T h e r e was n o c o r r e l a t i o n b e t w e e n tlle Q - T i n t e r v a l ( a v e r a g e , 0.25 s e c o n d w i t h r a n g e , 0.22 to 0.30 s e c o n d ) a n d tile d e g r e e of p u l m o n a r y h y p e r t e n s i o n or t h e p r e s e n c e of a left-to-right shunt. S T .segment. I n 2 i n f a n t s , a s i g n i f i c a n t S T
segment depression was present m the right p r e c o r d i a l leads. B o t h i n f a n t s h a d a leftto-right shunt and a mean pulmonary arterial p r e s s u r e less t h a n 30 r a m . H / . Q R S axis. T h e Q R S axis in t h e f r o n t a l p l a n e was +149 d e g r e e s w i t h a r a n g e of 105 to 190 degrees. T h e m e a n axis of t h e i n f a n t s w i t h s h u n t w a s slightly l o w e r (145 d e g r e e s ) t h a n t h e m e a n axis o f t h o s e w i t h o u t s h u n t s
Volume 67 Number 4
Electrocardiogram in normal newborn
(153 degrees), but the difference was not statistically significant. Q wave. The incidence of a Q wave in the various leads is given in Table II. There was a higher incidence in precordial lead V6 in infants with a left-to-right shunt (8 out of 14) as opposed to those without a shunt (3 out of 14), but these differences were not statistically significant. T h e average mean pulmonary arterial pressure in the infants with a Q wave in V6 was 34.5 (_+ 9.4) ram. Hg, as opposed to the average pressure of the infants without a Q wave in V6 which was 36.5 (+ 8.6) ram. Hg. This difference was not statistically significant. R wave. T h e amplitude of the R and S waves, the R / S ratio in the precordial leads, the mean pulmonary arterial pressure, and the pulmonary to systemic pressure ratio are presented in Table I I I . T h e mean values of these measurements as well as the standard deviation are also given. T h e mean values of R and S wave amplitude in the limb leads are given in Table IV. There was no correlation between the height of the R wave and the mean pulmonary arterial pressure, the presence or absence of left-to-right shunts, or the pulmonary to systemic mean pressure ratio (Fig. 1). Only 2 infants had R waves in Vz more than 24 mm.
S wave. No significant correlation between the depth of the S wave and the mean pulmonary arterial pressure or the pulmonary to systemic pressure ratio was found (Table I I I ) . In the group of babies with a shunt, the mean S wave was slightly higher in leads VI, V~, and V4 and somewhat lower in V6 (Fig. 1). R / S ratio. T h e median, minimum, and m a x i m u m values of the R / S ratio in the precordial leads are listed in Table I I I . There was no significant correlation of this ratio with the mean pulmonary arterial pressure, the presence of left-to-right shunt, or the pulmonary to systemic pressure ratio. T h e R / S ratio in one or more of the right precordial leads was less than 1 in 3 infants, and in all 3, a left-to-right shunt was present. T h e R / S ratio in the left precordial leads was greater than 1 in 6 of the 28 infants (22 per cent), and, in 5 of these, a leftto-right shunt was present. T wave. Correlation of T-wave deflection and the mean pulmonary arterial pressure is shown in Table V and Fig. 2. There was a significant correlation (P ~ 0.01) between negative T waves in RV3 or Vz and the mean pulmonary arterial pressure. Infants with a negative T wave in these leads had a lower pulmonary arterial pressure than did infants with an upright T wave, who had sig-
S WAVE in 28 normal newborn infanfs
R WAVE in 28 normal newborn infants
o---o Infonfs wifh L-~Rf shunf (14) 9 9 I n f o n f s w i f h o u f L - > R f s h u n f (14)
25
25-
~o
20.
oSS
1 5 84
mm
(140mV) I0-
~III
~
0
i
i
~
10-
'o
5"
5-
58 1
0
i
Fig. 1. Mean S and R waves in precordial leads of 14 infants with left-to-right ductal shunts and 14 infants with no ductal shunts. The small differences between the 2 groups are not statistically significant.
582
Emrnanouilides,
October 1965
Moss, and Adams
T a b l e I I I . R a n d S w a v e a m p l i t u d e a n d R / S ratio in p r e c o r d i a l leads of 28 n o r m a l n e w b o r n infants Case No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 2O 21 22 23 24 25 26 27 28
Meant and S.D.
V,,R
R
I
V,
s
R/S
10.0 6.0 5.0 6.0 10.0 9.0 6.0 15.0 7.0 12.0 17.0 13.0 16.0 12.0 7.0 12.5 8.0 13.0 5.5 9.0 8.0 13.0 5,0 15.0 10.0 11.0 20.0 16.0
4.0 1,5 3.5 1.0 9.0 6.0 1.0 1.5 1.5 5.0 1.5 5.(1 2.0 ---2.5 2.0 1.0 -3.0 16.(I 1.5 0.5 2.0 3.O 0.5 1.0 4.0
2.5 4.0 1.4 6.0 1.1 1.5 6.0 10.0 5.0 2.4 11.0 2.6 8.0
3.0 0.5 9.0 25.0 7.5 3.3 22.0 20.0 4.0
10.6
2.8
6.0
+4.0
3.3
5.0 4.0 13.0 ~o
(1.4-32.0)
R
S
V,
R/S
21 11 15 22 17 10 13 20 15 20 26 11 23 15 9 20 10 20 8 13 10
12.0 4.0 12.0 28.0 17.0 5.0 5.0 3.0 9.0 11.0 14.0 4.0 8.0 0.5 16.0 4.0 5.0 1.0 7.0 15.0
45.00 1.25 2.50 4.00 8.00 1.90 0.66
18
4.5
4.00
8 23 17 16 25 20
3.0 6.0 6.0 2.0 2.0 12.0
2.70 3.80 2.9O 8.00 12.50 1.70
16.2
7.7
5.3
6.3
1.70
R
I
s
20 21 15 21 22 18 26 26 18 28 24 17 15 7 13 22 12 22 8 12 16 2t 16 36 24 16 15 10
26 17 25 32 42 21 24 18 18 26 22 11 20 5 17 30 17 20 19 22 26 7 23 21 20 15 23 11
2.5
18.6
20.6
(0.66-18.0)
6.4
7.4
2.20 1.20
0.79 1.00
2.00 2.60 6.60 1.70 1.80 1.80
2.70 3.00
I
R/S
0.70 1.20
0.60 0.63 0.48 0.89 I.I0 1.40 1.00
1.10 1.10 1.50
0.75 1.40
0.77 1.25
0.70 1.10 0.42 0.54 0.61 3.00 0.70 1.40 1.20
1.10 0.66 0.90 1.0 (0.42-3.0)
*Infants with left-to-right shunt through the ductus arteriosus "~For R / S ratios, the median was given with the m i n i m u m and maximum values in parentheses.
T a b l e I V . M e a n (+_ S.D.) R a n d S w a v e a m p l i t u d e in m i l l i m e t e r s (1//10 m v . ) in limb leads Lead
R wave (Mean +- S.D.)
I II III AVR*
1.6 4.8 8.7 4.7
+ + + +
1.3 3.2 3.0 2.5
AVL AVF
1.5 + 1.0 6.2 + 3.6
S wave (Mean +- S.D.)
6.8 3.2 0.25 9.8 (1.0) 7.2 1.3
+ + + +
2.9 2.7 0.75 1.1 (1.3) + 2.6 + 1.4
"~S waves were present in only 13 cases. Q waves were present in 14 eases (in parentheses) and in one case an r R complex was present.
nificantly h i g h e r pressure. H o w e v e r , it is imp o r t a n t to recognize t h a t some o v e r l a p p i n g was observed, a n d because of the small n u m b e r of infants w i t h n e g a t i v e T w a v e s in these leads, the c a l c u l a t e d statistical significance
m a y n o t a p p l y to i n d i v i d u a l cases. T h e a v e r age p u l m o n a r y arterial pressure of infants w i t h d i p h a s i c T w a v e s in the s a m e leads ( V a R a n d V1) was g r e a t e r t h a n t h a t of infants w i t h n e g a t i v e T waves, b u t less t h a n t h a t of infants w i t h u p r i g h t T waves. T h e s e differences, h o w e v e r , w e r e n o t statistically significant ( T a b l e V ) . E i g h t y - n i n e per c e n t of the infants h a d u p r i g h t or diphasic T waves in V~, a s o m e w h a t h i g h e r i n c i d e n c e t h a n t h a t o b s e r v e d by K e i t h a n d c o - w o r k e r s ? 2 All 3 infants w i t h n e g a t i v e T w a v e s in this series w e r e older t h a n 10 hours of age, a n d , in 2, an associated depression of the S T segm e n t was present. T h e r e was some c o r r e l a tion (p < 0.05) b e t w e e n the i n c i d e n c e of a n e g a t i v e T w a v e in V6 a n d the level of p u l m o n a r y arterial pressure. T h e infants w h o s h o w e d n e g a t i v e or flat T w a v e s in V~ h a d
Volume 67 Number 4
Electrocardiogram in normal newborn
V~
.
I sq
16 19 18 14 18 10 28 22 15 2O 20 18 i1 8 10 16 13 24 9 11 15 17 13 26 22 20 18 15
26 24 30 24 42 24 26 20 16 26 34 13 21 13 12 22 20 20 19 27 30 9 26 22 30 15 14 20
16.6
22.3
5.1
7.3
V5
RI
R/S 0.65 0.80 0.60 0.58 0.43 0.42 1.30 1.10 0.93 0.78 0.59 1.40 0.48 0.80 0.83 O.72 0.65 1.20 0.45 0.41 O.5O 1.90 0.50 1.20 O.75 1.30 1.28 O.75
15 13 10 6 7 9 18 9 11 11 13 I0 6 5 8 13 9 13 6 4 10 12 9 17 12 17 10 13
V6
s
R/S 0.65 1.30 0.50 0.43 0.25 0.49 1.00 0.60 0.68 0.64 0.45 0.90 0.37 0.38 1.00 1.90 0.56 0.72 0.60 0.30 0.44 1.00 0.60 0.85 0.43 1.I0 0.60 0.85
22 10 20 14 28 20 18 15 16 17 28 11 16 13 8 7 16 16 10 12 22 12 15 20 26 16 17 15
583
Mean
R/S
PAP
4.0 8.0 10.0 4.0 3.0 4.0 10.0 3.0 4.0 2.0 9.0 3.0 3.0 3.0 5.0 13.0 2.5 7.0 5.0 2.5 4.0 4.0 8.0 7.0 7.0 8.0 5.0 7.0
7.0 3.0 12.0 6.0 14.0 9.0 9.0 7.0 9.0 7.O 16.0 2.5 9.0 11.0 4.0 1.0 7.5 10.0 10.0 7.5 2.0 4.5 10.0 11.0 17.0 15.0 11.0 8.0
0.55 2.60 0.90 0.66 0.21 0.44 1.10 0.43 0.44 O.28 0.56 1.20 0.30 0.27 1.25 13.00 0.30 0.70 0.50 0.30 2.00 0.90 0.80 0.68 0.41 0.53 0.45 0.87
45* 29* 47* 47* 29* 52* 45* 27* 33 58* 33 29* 50* 29* 22* 37 44 27 22 31 35* 42 27 32 38 36 30 32
0.88 0.53 0.76 0.78 0.53 0.85 0.83 0.64 0.51 0.83 0.53 0.56 0.91 0.58 0.45 0.56 0.65 0.61 0.61 0.55 0.58 0.66 0.54 0.55 0.57 0.61 0.47 0.64
0.55
39.5
0.67
9.1
0.14
0.72
10.5
16.4
0.6
5.5
8.5
(0.4-1.9)
3.6
5.4
(0.23-1.9)
2.8
4.1
(0.21-12.0)
60-
40-
PAP rnrn,Hg 3020-
I0-
O-
Upright
1
Diphasic Necjative
VI
DiphasicNegative or Flat
Upright VS
Fig. 2. Correlation between T waves in VI and VG and mean pulmonary arterial pressure (PAP) in 28 normal newborn infants. Note that infants with negative T waves in V1 have lower mean pulmonary arterial pressure than those with positive T waves (p < 0.01). Negative T waves in V6 were associated with higher mean pulmonary arterial pressures than positive T waves (p < 0.05). The majority of infants with negative T waves in Ve had a left-toright shunt through the ductus arteriosus.
Emmanouilid~%
584
Moss, and A d a m s
T a b l e V. Correlation of T wave direction a n d m e a n p u l m o n a r y arterial pressure in 28 n o r m a l n e w b o r n infants
T Wave +
I
II
n 26
-
'2
•
0
+ -
28 0
I PAP I (mm. Hg) 35.0 41.0
PdP/ AOP .63 .71
36.0 .63 . . . .
-+
0
III
+ •
25 2 I
36.0 34.0 22.0
.65 .52 .45
AVR
+ -+
3 24 1
40.0 360 22.0
.68 .63 .61
AVL
+ •
'2'2 4 2
36.0 36.0 29.0
.64 .63 .58
AVF
+
28
36.0
.63
V:,R
+ +_
14 ') 1'2
40.0 26.0 33.0
.68 .51 .60
+
16
.65 .52 .63
V,
-
3
•
9
38.0 28.1) 34.0
V~
+ -
17 5 6
37.0 36.0 32.0
.65 .66 .56
V~
+ +
13 8 7
35 0 40.0 32.0
.62 .69 .58
+
18
,61 .71 .63 .61 .74 .55
V~
-+
4
33.0 41.0 38.0
+ +
22 5 1
34.0 43.0 32.0
-
Vo
6
PAP, mean puhnonary arterial pressme. PYtP/ASP, puhnonary to systemic pressure ratio. +, upright T wave. -,
negative T wave.
-+, diphaslc T wave.
higher p u l m o n a r y arterial pressures. No significant correlation was found between the presence or absence of a shunt a n d the direction of the T wave in V1. W h e n pulm o n a r y to systemic pressure ratio was related with T-wave direction, there was a correlation (p < 0.05) only for lead RV.~ and V~ b u t not for V6.
October 1965
DISCUSSION I n the present study, a correlation was made between various electrocardiographic measurements a n d the h e m o d y n a m i c findings in 28 normal full-term infants from 1 to 27 hours old. M e a n p u l m o n a r y arterial pressure, p u l m o n a r y to systemic pressure ratio, and presence or absence of a left-to-right shunt through the duetus arteriosus were correlated with electrocardiographic p a r a m eters. T h e results indicate that the electrocardiogram reflects the hemodynamics in the normal newborn. Keith a n d collaborators ~ reported hemodynamic observations in 2 n e w b o r n infants with respiratory distress syndrome. O n the basis of these observations, they described 2 types of electrocardiographic patterns based on the R / S ratio a n d the depth of the S wave in the right precordial leads. They postulated that infants with an R / S ratio less than 1 or with a deep S wave in V~ or V,_, have a large left-to-right shunt through the ductus arteriosus and a relatively lower pulm o n a r y vascular resistance, while infants with a ratio of more than 1 or tall R waves in VI a n d V2 have a smaller left-to-right shunt a n d a higher p u l m o n a r y vascular resistance. T h e same authors analyzed a n u m ber of electrocardiograms of infants with respiratory distress syndrome a n d f o u n d that a better prognosis was associated with the latter electrocardiographic patterns ( R / S > 1 a n d tall R waves in V1 a n d V2). I n the present investigation, a positive correlation could not be demonstrated between the R or S waves, the R / S ratios a n d the m e a n p u l m o n a r y arterial pressure, or the p u l m o n a r y to systemic pressure ratio. Walsh s found that babies u n d e r 1 hour of age had significantly higher R waves in the right precordial leads a n d deeper S waves in the left precordial leads t h a n infants beyond that age. T h e m e a n p u l m o n a r y arterial pressure during the first hour of life is equal to or higher t h a n systemic pressure, a n d a rlght-toleft s h u n t through the ductus arteriosus is usually present? s, ~7 This agrees with the studies conducted by Walsh. s Beyond 1 hour of age the p u l m o n a r y ar-
Volume 67 Number 4
terial pressure falls and by the end of the first day decreases to approximately 50 per cent of the systemic pressure level? 8 The right-to-left shunt is eventually replaced by a left-to-right shunt?~, as-2z, 27 A hemodynamically significant left-to-right shunt is generally present only in infants less than 15 hours of age? ~' 18, s0 The mean values of S waves in RV3, Va, and V2 of infants with a left-to-right shunt in the present study were slightly higher than those of infants without a detectable shunt (Fig. 1). However, these differences were not statistically significant. The discrepancy between these findings in normal infants and those of Keith 12 in infants with the respiratory distress syndrome may be due to larger shunts known to be present in this syndrome. In 3 infants of the present study, the R / S ratio in V1 was equal to or less than 1, and all 3 had a left-to-right shunt through the ductus arteriosus. This observation suggests the possibility that during the first 24 hours of life an R / S ratio in V1 of less than 1 may be associated with "left ventricular" loading due to a left-to-rlght shunt via the ductus arteriosus. A higher incidence of Q waves in V6 was observed in babies with shunts, although the difference was not statistically significant. All 3 cases with an R / S ratio in V1 equal to or less than 1 had Q waves in V6. In 6 instances, the R / S ratio in V6 was more than 1 and a left-to-right shunt was present in 5 of these. In the 4 infants of this group who were under 13 hours of age, the average pulmonary to systemic pressure ratio was 0.51 with a range of 0.45 to 0.56. In the infants under 13 hours of age with an R / S ratio in V6 less than l, the average pressure ratio was higher (0.73, range 0.53 to 0.91). This is in agreement with the observed gradual increase in the R / S ratio in V6 with increasing age, presumably related to increasing "left ventricular preponderance. ''2, 3, 8, 28, 29, 30 However, no anatomical changes are known to occur during the first 24 hours that could account for this change. TM The "left preponderance" must be a reflection of the drop in right ventricular pressure resulting
Electrocardiogram in normal newborn
58 5
from the reduction of pulmonary vascular resistance. Another contributing factor may be the load placed upon the left ventricle by an increase in peripheral vascular resistance occurring after removal from the placental circulation and by the left-to-right shunt which is present during the first day of life. The results of this study also indicate a positive correlation between the direction of T waves in the right precordial leads and the degree of pulmonary hypertension (Table V and Fig. 2). This observation confirms the hypothesis proposed by several authors that pulmonary hypertension may be the cause of the upright T wave in the right precordial leads in the first and second day after birth?a, 1~, ~2, 32, a3 The negative T waves in the left precordial leads during the first day of life have been interpreted as evidence of "left ventricular loading. ''14, 22 However, in this study, a correlation of negative T waves in the left precordial leads and the degree of pulmonary hypertension was found. In 6 infants in whom a flat or negative T wave was observed, a higher mean pulmonary arterial pressure was present (Table V). Five of these infants were under 13 hours of age and 4 had a left-to-right shunt. This high incidence of negative T waves may be related to the left-to-right shunt characteristically observed in this age group. 15' is, 2o Overloading of the left ventricle may well occur as a result of flow through the ductus arteriosus into a restricted pulmonary vascular bed. Although the height of P waves did not reach accepted abnormal values (more than 2.5 m m . ) , the data indicate that a P wave of 2 mm. or more in leads II, V1, or Vz was associated with a mean pulmonary arterial pressure greater than 30 mm. Hg. This observation that taller P waves occurred in infants with higher mean pulmonary arterial pressure may indicate some degree of atrial dilatation associated with right ventricular hypertension. SUMMARY
The electrocardiogram and hemodynamic data were correlated in 28 normal newborn
5 8 6 Emmanouilides, Most, and Adams
infants aged 1 to 27 hours. T h e data indicate that hemodynamic changes occurring after birth are reflected in the electrocardiogram of the n o r m a l newborn infant. 1. A significant correlation between the m e a n p u l m o n a r y arterial pressure a n d the T-wave deflection in V:d~, and V1 was found. I n f a n t s with upright T waves in these leads tend to have higher p u l m o n a r y arterial pressures than those with negative T waves (p < 0.01). 2. Infants with negative T waves in V,; also had higher p u l m o n a r y arterial pressures than those with upright T waves (p < 0.05). T h e majority of these infants were u n d e r 10 hours of age a n d had a left-to-right shunt via the ductus arteriosus. 3. All infants with an R / S ratio of less t h a n 1 in the right precordial leads had a left-to-right shunt. 4. A n R / S ratio in V,; of more than 1 was associated with a lower p u l m o n a r y to systemic pressure ratio. 5. No significant correlation was found between R a n d S waves in the precordial leads and the p u l m o n a r y arterial pressure, the presence of left-to-right shunts through the ductus arteriosus, or the p u l m o n a r y to systemic pressure ratio. REFERENCES
1. Ziegler, R. F.: Characteristics of the unipolar precordial electrocardiogram in normal infants, Circulation 3: 438, 1951. 2. Ziegler, R. F.: Electrocardiographic studies in normal infants and children, Springfield, Ill., 1951, Charles C Thomas, Publisher. 3. Sodi-Pollares, D., Portillo, B., Cisneros, F., De La Cruz, M. V., and Acosta, A. R.: Electrocardiography in infants and children, Pediat. Clin. North America 5: 871, 1958. 4. Micha~lsson, M.: Electrocardiographic studies in the healthy newborn, Acta paediat. 48, Suppl. 117: 108, 1959. 5. Datey, K. K., and Bharucha, P. E.: Electrocardiographic changes in the first week of life, Brit. Heart J. 22: 175, 1960. 6. Rothfeld, E. L., Wachtel, F. W., Karlen, W. S., and Bernstein, A.: The evolution of the vectorcardiogram and electrocardiogram of the normal infant: I. The normal newborn, Am. J. Cardiol. 5: 439, 1960. 7. DePasquale, N. P., and Burch, G. E.: The electrocardiogram, ventricular gradient, and spatial vectorcardiogram during the first week of life, Am. J. CardioI. 12: 482, 1963.
October 1965
8. Walsh, Z. S.: The electrocardiogram during the first week of life, Brit. Heart J. 25: 784, 1963. 9. Craige, E., and Harned, H. S.: Phonocardiographic and electrocardiographic studies in normal newborn infants, Am. Heart J. 65: 180, 1963. 10. Keen, E. N.: The postnatal development of the human cardiac ventricles, J. Anat. 89: 484, 1955. 11. Penaloza, D., Gamboa, R., Dyer, J., Echevarria, M., and Marticorena, E.: The influence of high altitudes on the electrical activity of the heart. I. Electrocardiographic and vectorcardiographic observations in the newborn, infants, and children, Am. Heart J. 59: 111, 1960. 12. Keith, J. D., Rose, V., Braudo, M., and Rowe, R. D.: The electrocardiogram in the respiratory distress syndrome and related cardiovascular dynamics, J. PEDIAT. 59: t67, 1961. 13. Ziegler, R. F.: The importance of positive T waves in the right precordial electrocardiogram during the first year of life, Am. Heart J. 52: 533, 1956. 14. Halt, G., and Gasul, B. M.: The evolution and significance of T wave changes in the normal newborn during the first seven days of life, Am. J. Cardiol. 12: 494, 1963. 15. Moss, A. J., Emmanouilides, G., and Duffle, E. R., Jr.: Closure of the ductus arteriosus in the newborn infant, Pediatrics 32: 25, 1963. 16. Moss, A. J., Duffle, E. R., Jr., and Emmanouilides, G. C.: Blood pressure and vasomotor reflexes in the newborn infant, Pediatrics, 32: I75, 1963. 17. Moss, A. J., Emmanouilides, G. C., Adams, F. H., and Chuang, K.: Response of ductus arteriosus and pulmonary and systemic arterial pressure to changes in oxygen environment in newborn infants, Pediatrics 33: 937, 1964. 18. Emmanouilides, G. C., Moss, A. J., Duffle, E. R., Jr., and Adams, F. H.: Pulmonary arterial pressure changes in human newborn infants from birth to three days of age, J. PEDIAT. 65: 327, 1964. 19. Adams, F. H., and Lind, J.: Physiologic studies on the cardiovascular status of normal infants (with special reference to the ducms arteriosus), Pediatrics 19: 431, 1957. 20. Rudolph, A. M., et al.: Studies on the circulation in the neonatal period. The circulation in the respiratory distress syndrome, Pediatrics 27: 551, 196l. 21. Rowe, R. D., and James, L. S.: The normal pulmonary arterial pressure during the first year of life, J. PEDIAT.51: I, 1957. 22. Castellanos, A., Jr., Lemberg, L., and Castellanos, A.: The vectorcardiographie significance of upright T waves in V, and V2 during the first months of life, J. PEmAT. 62: 827, 1963. 23. Cosby, R. S., Levinson, D. C., Zinn. W. J., Dimltroff, S. D., and Griffith, G. C.: Congenital heart disease: An analysis of electro-
Volume 67 Number 4
24.
25. 26. 27.
cardiographic patterns in forty-four patients with elevated right ventricular pressure, Am. Heart J. 44: 581, 1952. Goodwin, J. F.: The electrocardiogram in normal children and in children with right ventricular hypertrophy, Brit. Heart J. 14: 173, 1952. Hollman, A.: Electrocardiographic diagnosis of right ventricular hypertrophy in infancy and childhood, Brit. Heart J. 20" 129, 1958. Vince, D., and Keith, J. D.: The electrocardiogram in ventricular septal defect, Circulation 23: 225, 1961. Saling, E.: Neue Untersuchungergebnisse fiber den Kreislauf des Kindes unmittelbar naeh der Geburt, Arch. Gyn~ik. 194: 287, 1960.
28. Rothfeld, E. L., Wachtel, F. W., Karlen, W. S., and Bernstein, A.: The evaluation of the
Electrocardiogram in normal newborn
29. 30.
31. 32. 33.
587
vectorcardiogram and electrocardiogram in the normal infant. II. Transition toward adult patterns, Am. J. Cardiol. 5: 450, 1960. Scott, O., and Franklin, D.: The electrocardiogram in the normal infant, Brit. Heart J. 25: 441, 1963. Lucas, R. V., Jr., St. Geme, J. W., Jr., Anderson, R. C., Adams, P., Jr., and Ferguson, D. J.: Maturation of the pulmonary vascular bed. A physiologic and anatomic correlation in infants and children, Am. J. Dis. Child. 101: 467, 1961. Dawes, G. S.: Changes in the circulation at birth, Brit. M. Bull. 17: 148, 1961. Stern, L., and Lind, J.: Neonatal T-wave patterns, Acta paediat. 49" 329, 1960. Walsh, S. Z.: The S-T segment and T-wave during the first week of life, Brit. Heart J. 26: 679, 1964.