ECG Sweep: Interactive ECG Simulator

ecgsweep

Simulator 12-Lead Axis Flashcardsupdates

Cardiac axis

Where the mean QRS vector points in the frontal plane

Normal axis+59°normal -30° to +100°

Axisdrag or use arrows

Findings

Lead I: positive
aVF: positive
Narrows to: Normal quadrant → 0° to +90°
Measured: 59.0° off the drawn beat

Only the QRS turns. The P and T stay where a normal heart puts them, because axis means the QRS axis.

Normal, and what moves it

Nearer +90° in children and tall, thin adults
Nearer 0° with age, obesity and pregnancy
A normal axis does not rule out disease: right bundle branch block alone leaves it normal

The leads sit as a printed ECG shows them: I, II and III, then aVR, aVL and aVF. Cabrera lays them out in the order the dial runs, from -30° to +120°. aVR is drawn as recorded, looking along -150°, up and to the right and away from the heart, which is why it is negative on almost every normal ECG.