The following ECG tracing was recorded in a 14 y/o male. Well do a step by step assessment.
1) Rhythm
Upright P-waves in inferior leads prior to every QRS complex --> Sinus Rhythm
2) Heart Rate
Counting the boxes between the R-waves of the first and second beat --> 11 boxes
50mm/s strip --> 1 box =100ms, 11 boxes = 1100ms, 60.000/1100 = 55 bpm
3) QRS axis
Inferior leads (II/III/aVF) entirely positive (pure R, no S), lead I more positive than negative (R/S = 2) --> axis +80°
4) Intervals
PR 110ms (short), QT 410ms = QTc 390ms (Bazett formula; normal)
5) QRS duration & morphology
QRS 80ms (normal), no bundle branch block morphology
6) Chest leads
R-wave transition (R-wave gets larger than S-wave) in V4 (normal transition).
Negative T wave in V1, biphasic in V2 (normal for age).
J-point elevation V2-V4 (max. 1.5mV), suggestive of benign early repolarisation (BER) in adolescent patients.
7) PR-segment & ST-segment
No delta-wave, isoelectric PR-segment.
BER, no ischemic ST changes.
8) Arrhythmias / premature beats
No premature ventricular or atrial contractions. No arrhythmia present.
9) Interpretation
Relative sinus bradycardia, BER, short PR suggestive of fast AV nodal conduction. Overall normal ECG in an adolescent.
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