The authors present a brief account of data reported in the recent literature on the evaluation of the Q wave in leads, II, III, aVF in clinically healthy subjects and in patients with ischaemic heart disease, in particular in conjunction with focal myocardial lesions. A marked Q wave in these leads is not necessarily a manifestation of clinical disease (it may be due to a changed position of the electric axis of the heart) and conversely the absence of the Q wave in leads II, III, aVF does not imply clinical absence of disease (most frequently a low myocardial infarction). It is not possible to differentiate Q waves in leads III and aVF into positional and abnormal ones according to their changes during deep inspiration. Q waves in the inferior leads present the picture of myocardial infarction of the lower, or frequently posterior, possibly laterally left ventricular wall. Correct evaluation of the abnormality (normality) of the genesis and development of Q waves on the electrocardiogram is possible only after integration of anamnestic data, clinical follow-up and results of auxiliary examination methods. Recording of the posterior chest leads and in particular vectorcardiographic examination and mapping of electric potentials of the heart on the body surface may prove helpful. These methods provide more detailed and spatial visualization of the electric field of the heart.

Keywords: Coronary Disease /physiopathology/; Electrocardiography; Heart /physiopathology/; Humans; Myocardial Infarction /physiopathology/