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A excellent description of the neonatal electrocardiogram has been made by Schwarz et al.<cite>schwarz1</cite><cite>schwarz2</cite> | |||
==Heart Axis== | ==Heart Axis== | ||
{| | {| class="wikitable" font-size="80%" width="100%" style="border:1px solid #E2ACB1;border-spacing:8px;" border="1" | ||
|+ Normal heart axis values<cite>aha</cite> | |||
!Age | !Age | ||
!QRS Axis Normal Values | !QRS Axis Normal Values | ||
!Abnormal Values | !Abnormal Values | ||
!Description | !Description | ||
|- | |||
|Adult | |||
| -30° to 90° | |||
| | |||
{| | |||
|- | |||
| <-30° | |||
|- | |||
| -30° to -45° | |||
|- | |||
| -45° to -90° | |||
|- | |||
| 90° to 120° | |||
|- | |- | ||
| | | 90° to 180° | ||
| | |} | ||
| | | | ||
{| | |||
| | |||
|- | |- | ||
|Left-axis deviation | |Left-axis deviation | ||
Moderate left-axis deviation | |- | ||
Marked left-axis deviation | |Moderate left-axis deviation | ||
Moderate right-axis deviation | |- | ||
Marked right-axis deviation | |Marked left-axis deviation | ||
|- | |||
|Moderate right-axis deviation | |||
|- | |||
|Marked right-axis deviation | |||
|} | |||
|- | |- | ||
|8 to 16 years | |8 to 16 years | ||
Line 38: | Line 50: | ||
Left-axis deviation | Left-axis deviation | ||
|- | |- | ||
|1 to 5 | |1 year to 5 years | ||
|5° to 100° | |5° to 100° | ||
|>100° | |>100° | ||
Line 44: | Line 56: | ||
|- | |- | ||
|1 mo to 1 y | |1 mo to 1 y | ||
|10° to 120° | | 10° to 120° | ||
|>120° | |>120° | ||
<10° to -90° | <10° to -90° | ||
|Right-axis deviation | |Right-axis deviation | ||
Left-axis deviation | Left-axis deviation | ||
|- | |||
|Neonate | |||
|30° to 90° | |||
|>190° to -90° | |||
<30° to <-90° | |||
|Extreme right axis deviation | |||
Left axis deviation | |||
|} | |||
==Conduction: definition of LBBB and RBBB in children== | |||
*'''RBBB''': if consistent morphology and if QRS width >90ms in children < 4 years and >100ms in children 4-16 years<cite>aha</cite> | |||
*'''LBBB''': if consistent morphology and QRS width >90ms in children < 4 years and >100ms in children 4-16 years<cite>aha</cite> | |||
==Normal neonatal ECG standards== | |||
{| class="wikitable" font-size="80%" width="100%" style="border:1px solid #E2ACB1;border-spacing:8px;" border="1" | |||
|+Normal neonatal ECG standards<cite>schwarz1</cite> | |||
! style="width:70px" | Age group | |||
! style="width:90px" | Heart rate<br/>(beats . min<sup>-1</sup>) | |||
! style="width:105px" | Frontal plane<br/>QRS axis<sup>a</sup><br/>(degrees) | |||
! style="width:65px" | P wave<br/>amplitude<br/>(mm) | |||
! style="width:100px" | P-R<br/>interval<sup>a</sup><br/>(s) | |||
! style="width:100px" | QRS<br/>duration<sup>a</sup><br/>V<sub>5</sub> | |||
! style="width:40px" | Q III<sup>c</sup> (mm) | |||
! style="width:40px" | QV<sub>6</sub><sup>c</sup> (mm) | |||
! style="width:40px" | RV<sub>1</sub><sup>b</sup> (mm) | |||
! style="width:40px" | SV<sub>1</sub><sup>b</sup> (mm) | |||
! style="width:50px" | R/S V<sub>1</sub><sup>c</sup> | |||
! style="width:40px" | RV<sub>6</sub><sup>b</sup> (mm) | |||
! style="width:40px" | SV<sub>6</sub><sup>b</sup> (mm) | |||
! style="width:50px" | R/S V<sub>6</sub><sup>c</sup> | |||
! style="width:70px" | SV<sub>1</sub> + RV<sub>6</sub><sup>c</sup> (mm) | |||
! style="width:70px" | R + SV<sub>4</sub><sup>c</sup> (mm) | |||
|- | |||
|0–1 days | |||
| align="center" | 93–154 (123) | |||
| align="center" | +59 to +192 (135) | |||
| align="center" | 2·8 | |||
| align="center" | 0·08–0·16 (0·11) | |||
| align="center" | 0·02–0·08 (0·05) | |||
| align="center" | 5·2 | |||
| align="center" | 1·7 | |||
| align="center" | 5–26 | |||
| align="center" | 0–22·5 | |||
| align="center" | 9·8 | |||
| align="center" | 0–11 | |||
| align="center" | 0–9·8 | |||
| align="center" | 10 | |||
| align="center" | 28 | |||
| align="center" | 52 | |||
|- | |||
|1–3 days | |||
| align="center" | 91–159 (123) | |||
| align="center" | +64 to +197 (134) | |||
| align="center" | 2·8 | |||
| align="center" | 0·08–0·14 (0·11) | |||
| align="center" | 0·02–0·07 (0·05) | |||
| align="center" | 5·2 | |||
| align="center" | 2·1 | |||
| align="center" | 5–27 | |||
| align="center" | 0–21 | |||
| align="center" | 6 | |||
| align="center" | 0–12 | |||
| align="center" | 0–9·5 | |||
| align="center" | 11 | |||
| align="center" | 29 | |||
| align="center" | 52 | |||
|- | |||
|3–7 days | |||
| align="center" | 90–166 (129) | |||
| align="center" | +77 to +187 (132) | |||
| align="center" | 2·9 | |||
| align="center" | 0·08–0·14 (0·10) | |||
| align="center" | 0·02–0·07 (0·05) | |||
| align="center" | 4·8 | |||
| align="center" | 2·8 | |||
| align="center" | 3–24 | |||
| align="center" | 0–17 | |||
| align="center" | 9·7 | |||
| align="center" | 0·5–12 | |||
| align="center" | 0–9·8 | |||
| align="center" | 10 | |||
| align="center" | 25 | |||
| align="center" | 48 | |||
|- | |||
|7–30 days | |||
| align="center" | 107–182 (149) | |||
| align="center" | +65 to +160 (110) | |||
| align="center" | 3·0 | |||
| align="center" | 0·07–0·14 (0·10) | |||
| align="center" | 0·02–0·08 (0·05) | |||
| align="center" | 5·6 | |||
| align="center" | 2·8 | |||
| align="center" | 3–21·5 | |||
| align="center" | 0–11 | |||
| align="center" | 7 | |||
| align="center" | 2·5–16 | |||
| align="center" | 0–9·8 | |||
| align="center" | 12 | |||
| align="center" | 22 | |||
| align="center" | 47 | |||
|- | |||
|1–3 months | |||
| align="center" | 121–179 (150) | |||
| align="center" | +31 to +114 (75) | |||
| align="center" | 2·6 | |||
| align="center" | 0·07–0·13 (0·10) | |||
| align="center" | 0·02–0·08 (0·05) | |||
| align="center" | 5·4 | |||
| align="center" | 2·7 | |||
| align="center" | 3–18·5 | |||
| align="center" | 0–12·5 | |||
| align="center" | 7·4 | |||
| align="center" | 5–21 | |||
| align="center" | 0–7·2 | |||
| align="center" | 12 | |||
| align="center" | 29 | |||
| align="center" | 53 | |||
|- | |||
| colspan="16" | | |||
<ul> | |||
<li><sup>a</sup> 2nd–98th percentile (mean)</li> | |||
<li><sup>b</sup> 2nd–98th percentile (1 mm=100 µV)</li> | |||
<li><sup>c</sup> 98th percentile (1 mm=100 µV)</li> | |||
</ul> | |||
|} | |||
==Distinguishing tachyarrhythmias in infants== | |||
{| class="wikitable" font-size="80%" width="100%" style="border:1px solid #E2ACB1;border-spacing:8px;" border="1" | |||
|+ Distinguishing tachyarrhythmias in infants<cite>schwarz1</cite> | |||
! style="width:80px" | | |||
! style="width:200px" | Sinus tachycardia | |||
! style="width:200px" | SVT | |||
! style="width:200px" | Atrial flutter | |||
! style="width:200px" | VT | |||
|- | |||
| valign="top" | '''History''' | |||
| valign="top" | Sepsis, fever, hypovolaemia, etc. | |||
| valign="top" | Usually otherwise normal | |||
| valign="top" | Most have a normal heart | |||
| valign="top" | Many with abnormal heart | |||
|- | |||
| valign="top" | '''Rate''' | |||
| valign="top" | Almost always <230 b/min | |||
| valign="top" | Most often 260–300 b/min | |||
| valign="top" | Atrial 300–500 b/min. Vent. 1:1 to 4:1 conduction | |||
| valign="top" | 200–500 b/min | |||
|- | |||
| valign="top" | '''R-R interval variation''' | |||
| valign="top" | Over several seconds may get faster and slower | |||
| valign="top" | After first 10–20 beats, extremely regular | |||
| valign="top" | May have variable block (1:1, 2:1, 3:1) giving different ventricular rates | |||
| valign="top" | Slight variation over several beats | |||
|- | |||
| valign="top" | '''P wave axis''' | |||
| valign="top" | Same as sinus almost always visible P waves | |||
| valign="top" | 60% visible P waves, P waves <em>do not</em> look like sinus P waves | |||
| valign="top" | Flutter waves (best seen in LII, LIII, aVF, V<sub>1</sub>) | |||
| valign="top" | May have sinus P waves continuing unrelated to VT (AV dissociation), retrograde P waves, or no visible P waves | |||
|- | |||
| valign="top" | '''QRS''' | |||
| valign="top" | Almost always same as slower sinus rhythm | |||
| valign="top" | After first 10–20 beats, almost always same as sinus | |||
| valign="top" | Usually same as sinus, may have occasional beats different from sinus | |||
| valign="top" | Different from sinus (<em>not</em> necessarily ‘wide’) | |||
|- | |||
| colspan="5" | | |||
<ul> | |||
<li>SVT = Supraventricular tachycardia</li> | |||
<li>VT = ventricular tachycardia</li> | |||
</ul> | |||
|} | |} | ||
==References== | |||
<biblio> | |||
#aha pmid=19228822 | |||
#schwarz1 pmid=12269267 | |||
#schwarz2 pmid=12739597 | |||
</biblio> |