A QRS axis beyond +90°: lead I negative, aVF positive.
Right axis deviation means the frontal QRS axis is beyond +90°. Quick check: lead I negative, aVF positive. Causes include right ventricular strain or hypertrophy (pulmonary embolism, COPD), lateral infarction, left posterior fascicular block, and the normal axis of children and tall, thin adults, so it isn't always pathology.
Each is a standard 12-lead: 2.5 seconds of each lead in four columns, with 10 seconds of lead II along the bottom, drawn to scale (25 mm a second, 10 mm a millivolt). The measurements are under each one.
Right axis deviation with rS in I and aVL, qR in II, III and aVF, and a QRS under 0.12 s.
A QRS axis between -90° and 180° (the 'northwest'): lead I and aVF both negative, aVR positive.
Sinus rhythm, a normal axis, normal intervals, R waves growing from V1 to V5, and no ST elevation or depression.
The ECG tool in the app gives you a new 12-lead every time and walks you through reading it: rate, QRS, axis, then where the ST is up and down. It's part of the Paramedic level, and you can try 5 ECGs a day free.
Try the 12-lead drill
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