Pediatric Electrocardiography

Pediatric Electrocardiography

ECG

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Sequence of electrical activity in the heart forming the P-Q-R-S-T waves

I. Atrial depolarization Axis: 0-90 P wave is upright in I & AVF		II. Slow AV node conduction No electrical activity recorded by ECG PR interval is flat
III. Depolarization of the ventricular septum Axis: 180-270 Negative deflection in I & AVF		IV. Depolarization of the ventricles Axis: 0-90 Upright in I & AVF
V. Depolarization of the heart base Axis: 180-270 Negative deflection in I & AVF		VI. Repolarization of the Ventricles Upright deflection in I & AVF

Normal 12 Lead Electrocardiogram

Normal Values

Age	HR bpm	QRS axis degrees	PR interval seconds	QRS interval seconds	R in V1 mm	S in V1 mm	R in V6 mm	S in V6 mm
1st week	90-160	60-180	0.08-0.15	0.03-0.08	5-26	0-23	0-12	0-10
1-3wks	100-180	45-160	0.08-0.15	0.03-0.08	3-21	0-16	2-16	0-10
1-2 mo	120-180	30-135	0.08-0.15	0.03-0.08	3-18	0-15	5-21	0-10
3-5 mo	105-185	0-135	0.08-0.15	0.03-0.08	3-20	0-15	6-22	0-10
6-11 mo	110-170	0-135	0.07-0.16	0.03-0.08	2-20	0.5-20	6-23	0-7
1-2 yr	90-165	0-110	0.08-0.16	0.03-0.08	2-18	0.5-21	6-23	0-7
3-4 yr	70-140	0-110	0.09-0.17	0.04-0.08	1-18	0.5-21	4-24	0-5
5-7 yr	65-140	0-110	0.09-0.17	0.04-0.08	0.5-14	0.5-24	4-26	0-4
8-11 yr	60-130	-15-110	0.09-0.17	0.04-0.09	0-14	0.5-25	4-25	0-4
12-15 yr	65-130	-15-110	0.09-0.18	0.04-0.09	0-14	0.5-21	4-25	0-4
> 16 yr	50-120	-15-110	0.12-0.20	0.05-0.10	0-14	0.5-23	4-21	0-4

Normal ECG tracing:

Corrected QT interval

QT interval should be compared to the heart rate to determine if it is normal or prolonged. This could be done by referencing the measured QT interval to normal QT interval range for each heart rate, as obtained from normal population. Alternatively, the QT interval could be corrected to the heart rate using the Bazett formula:

QTc = QT / square root of RR interval

The table below provides the QTc for each listed QT intervals at various heart rates.

To determine the QTc, measure the QT interval from the onset of the QRS complex to the end of the T wave. Then determine the heart rate and find from the table below the QTc.

QT HR	0.20	0.25	0.30	0.35	0.40	0.45	0.50
50	0.18	0.23	0.27	0.32	0.37	0.41	0.46
52	0.19	0.23	0.28	0.32	0.37	0.42	0.46
54	0.19	0.23	0.28	0.33	0.38	0.42	0.47
56	0.19	0.24	0.29	0.34	0.38	0.43	0.48
58	0.20	0.24	0.29	0.34	0.39	0.44	0.49
60	0.20	0.25	0.30	0.35	0.40	0.45	0.50
63	0.21	0.25	0.31	0.36	0.41	0.46	0.51
66	0.21	0.26	0.31	0.36	0.42	0.47	0.52
68	0.22	0.26	0.32	0.37	0.43	0.48	0.53
71	0.22	0.27	0.33	0.38	0.44	0.49	0.55
75	0.23	0.27	0.34	0.39	0.45	0.51	0.56
79	0.24	0.28	0.34	0.40	0.46	0.52	0.57
83	0.24	0.29	0.35	0.41	0.47	0.53	0.69
88	0.25	0.29	0.36	0.43	0.49	0.55	0.61
94	0.26	0.30	0.38	0.44	0.50	0.56	0.63
100	0.27	0.31	0.39	0.45	0.52	0.58	0.65
107	0.28	0.32	0.40	0.47	0.53	0.60	0.67
115	0.28	0.35	0.42	0.49	0.55	0.63	0.69
125	0.29	0.36	0.43	0.51	0.58	0.65	0.72
136	0.30	0.38	0.45	0.53	0.60	0.68	0.75
150	0.32	0.40	0.47	0.56	0.63	0.71	0.79

Right Atrial Enlargement (RAE)

The P wave is taller than two small squares in infants and small children
and more than three small squares in older children and adults.

Left Atrial Enlargement (LAE)

The P waves are wide, more than two small squares (> 0.08 sec) in infants and small children
and more than three small squares (> 0.12 sec) in older children and adults.

Right Ventricular Hypertrophy (RVH)

This could present in many different forms:

R in V1 taller than 95% of normal PLUS S in V6 deeper than 95%.

rsR’ in V1 & V2 without widening of QRS complex as in bundle branch block. (The upper case R in rsR’ indicate that the R’ deflection is taller than the r wave.

qR in V1 & V2 .

Pure R wave in V1 & V2 , with or without ST & T changes indicative of strain.

Left Ventricular Hypertrophy (LVH)

R in V6 taller than 95% of normal and S in V1 deeper than 95%

Bi-Ventricular Hypertrophy (BVH)

Features of both RVH and LVH as above