Overview: No significant age-related differences for P wave amplitude to define RAE in children Therefore, adult RAE diagnostic criteria applied for all ages ECG features: Assumes sinus rhythm present P wave amplitude (≥1 of the following): II: ≥2.5 mm V1 or V2: initial positive deflection ≥1.5 mm

Heart rate (HR): measure of the frequency of cardiac cycles; expressed in beats per minute (BPM) Determining Heart Rate 3-step approach: (1) Locate R wave that falls on or near thick line (2) Count # of thick lines until next R wave (3) Use “300-150-100-75-60-50” rule Regular rhythms: If HR

Overview P wave: 1st positive/negative deflection & start of cardiac cycle Cardiac event: atrial depolarization Begins when SA node (normal) or neighboring atrial pacemakers fire; includes impulse transmission through internodal pathways, Bachmann bundle, & atrial myocytes 3 specialized pathways containing Purkinje fibers connecting SA node to AV node: (1) anterior,

Overview PR segment: flat, typically isoelectric segment representing time from end of P wave to start of QRS complex (note: does not include P wave) Cardiac event: impulse transmission through AV node, His bundle, bundle branches, & ventricular Purkinje system AV node allows for critical delay in conduction system &

ECG features: may precede clinical manifestations Rhythm disturbances: Atrial fibrillation: Incidence increases with age [1,2] May spontaneous revert to sinus rhythm after treatment [1,2] Frequency may be greater in triiodothyronine (T3) toxicosis compared to when both T3 & thyroxine (T4) are increased [3] Sinus tachycardia: More common than atrial fibrillation