cardiolab: Interactive ECG Simulator

cardiolab

Simulator 12-Lead Axis Flashcardsupdates

Cardiac axis

Where the mean QRS vector points in the frontal plane

Right axis deviation+140°normal -30° to +100°

Axisdrag or use arrows

Findings

Lead I: negative
aVF: positive
Narrows to: Right quadrant → +90° to +180°
Measured: 140.0° 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.

Causes of right axis deviation

Right ventricular hypertrophy
Acute right heart strain, such as pulmonary embolism
Left posterior fascicular block
Lateral myocardial infarction
Chronic lung disease
Dextrocardia or limb lead reversal
Normal in infants and young children

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.