Pediatric EKG
Step 1: Rate, Rhythm, Axis
1 Small box = 1mm = 0.04 sec
1 Large box = 5mm = 0.2 sec
6 Large Boxes = 30 mm = 1 sec
300 Large Boxes = 1 min
RATE
-If rate is fast, count R to R cycles in 6 large boxes and multiply by 10 (# cycles / 6 seconds X 10)
-If rate is slow, count # of large divisions b/t 2 R waves and divide into 300 (300 / # boxes)
-on unmounted paper, markers are placed at 3 sec intervals. Multiply the # of RR cycles by 20 for rate
-if rate is regular, use 300-150-100-75-60-50 method (counting large boxes)
Keep in mind these normal rates:
Neonates (110-150); 2 yrs (85-125); 4 yrs (75-115); 6yrs (65-100); 6 yrs (60-100)
RHYTHM:
Regular Rhythms
Normal rate:
- Sinus rhythm (P before every QRS, QRS before every P, all P waves look the same, upright P in leads I and AVF)
- Non-sinus rhythm (ectopic atrial pacemaker, accelerated AV, nodal rhythm, 2:1 AV block w/ sinus or atrial tach, implanted ventricular pacemaker)
Raid rate:
- Sinus tachy
- SVT (paroxysmal atrial tacht (PAT), a-flutter, junc tachy)
- V tach
Slower rate:
- Sinus brady
- AV nodal rhythm w/ SA block or complete AV block
- Idioventricular rhythm w/ SA block or complete AV
Irregular Rhythms:
Regularly Irregular: sinus arrhythmia
- Wenckebach (Mobitz I)
- Bigeminy or Trigeminy (atrial, AV nodal, ventricular)
Irregularly Irregular: Atrial fibrillation
- Arial flutter w/ variable AV block
- Ventricular fibrillation
- Infrequently irregular premature beats, second degree AV block
P-wave method-
3 criteria for sinus – 1) normal P wave axis (LLQ); 2) wave before each QRS; 3)
QRS after each P
Abnormal P axis or abnormal shape:
PAC (infrequent), wandering atrial pacemaker (gradual changes), ectopic atrial pacemaker, atrial situs inversus, incorrectly placed arm leads nodal rhythm w/ retrograde P wave conduction, SVT
Absent P waves:
Infrequent – SA block w/ nodal escape, nodal premature beats, PVCs
Constant – nodal rhythm, SVT, A-fib, idioventricular rhythm, V-tach
Multiple P waves before QRS:
AV block
AXIS
1) locate quadrant using leads I and aVF
2) find the limb lead w/ equiphasic QRS, the axis is perpendicular to this
3) find a lead w/ the tallest QRS, the QRS axis is close to the positive or negative of this lead
Step 2: P, Q, R, S, T
P – P axis is always positive
– P amplitude is normally < 3 mm
– P duration is max 0.1 sec in children, max 0.08 sec in infants < 1 y.o.
– Tall P waves mean right atrial hypertrophy (p-mitrale)
– pR interval varies w/ age and heart rate
– Long PR means AV block
– (myocarditis, ASD, endocardial cushion defect, Ebstein’s anomaly, toxicity to meds (digitalis quinidine), hyperkalemia, hypoxia)
Q – commonly present in I, II, III, aVF, and usually V5 and V6
– Q amplitude usually<5mm(except in lead III, up to 8 min)
– Q duration is 0.02-0.03 sec
– Deep but not wide Qs may mean vent hypertrophy (not overload LVH)
– Deep ad wide Qs may mean MI, myocardial fibrosis, or IHSS
Bazel’s formula: QTc= measure QT/square root of preceding R-R
- QTc should not exceed 0.44 sec, except in infants (up to 0.49 sec nl up to 6 mo old) Long QTc may be seen in hypocalcemia, myocarditis, head injury, CVA, quinidine, procainamide or LONG QT syndrome (Jerveil and Lange-Nielson, Romano Ward)
– Do not use cisapride (propulsid) in children w h/o prolonged QT
– QRS duration norms vary w/ age, 0.04 sec in preemies to 0.08 in adults
– Wide QRS means ventricular conduction defect, bundle branch block, WPW pre-excitation, vet arrhythmias/pacemake
R – R too tall for age in V1 suggestsRVH
– R too tall for age in V5 suggests LVH
– R prime- rsR’ (bunny ears) in V1 or V2 suggests RBBB
– R prime- rsR’ in V5 or V6 suggests LBBB
– R/S progression: progressive increase in R wave and decrease in S wave amplitude going from V1 to V6
– Seen in 3 yr olds thru adulthood
– May see complete reversal in neonates (tallest Rs in V1 and V2)
– 1mo to 3yrs see partial reversal (hybrid patterns ex: tallest Rs in V1, 6)
S – S too tall for age in V6 suggests RVH
– S too tall for age in V1 suggests LVH
– Look at R/S ratios as criteria for hypertrophy
– Big in V1 means RVH and big in V6 means LVH
– ST segment occurs after vent depolarization and before repolarization
– Normally horizontal and isoelectric
– Elevation or depression up to 1 min in limb leads OK
– Elevation or depression up to 2 mm in precordial leads OK w/ high/low ST segment consider peri/ myocarditis, MI/ ischemia, hypo/ hyperkalemia, ventricular, aneurysm, drug effect, intracranial pathology
T – Peaked T waves seen in hyperkalemia, LVH w/volume overload, CVA, posterior MI
– Flat T waves seen in normal newborns, hypothyroidism, hypokalemia, hypo/ hyperglycemia, peri/ myocarditis, MI, digitalis effect
