ECG Axis Interpretation
Cardiac axis represents the sum of depolarisation vectors generated by individual cardiac myocytes. Clinically is is reflected by the ventricular axis, and interpretation relies on determining the relationship between the QRS axis and limb leads of the ECG (below diagram) Since the left ventricle makes up most of the heart muscle under normal circumstances, normal cardiac axis is directed downward and slightly to the left: Normal Axis = QRS axis between -30° and +90°. Abnormal axis deviation, indicating underlying pathology, is demonstrated by: ...