Electrocardiogram (ECG) illustration showing septal Q wave loss. Under normal conditions, the ventricular initial depolarization from the left ventricular septum to the right ventricular septum produces physiological septal Q waves in the left leads (I, AVL, v5-v6). There is no septal Q wave in left leads of some healthy individuals, but it is more common in various pathological conditions, such as left ventricular septal fibrosis, ischemia, invasion of electrical inert substances and so on.