The authors present a brief account of contemporary findings in the literature on the evaluation of the Q wave in the electrocardiogram in leads II, III and aVF in disorders of the conduction of impulses (also combination with focal lesions of the heart muscle), in preexcitation of various extent, in hypertrophy and different focal and diffuse changes of the heart muscle. They mention briefly also other cardiac and extracardiac causes of the development and persistence of the Q wave in leads, II, III, aVF. They reached the main conclusion that isolated evaluation of this phenomenon only from the electrocardiogram can lead to erroneous conclusions, therefore they advocate comprehensive evaluation of the clinical condition of these patients (in indicated cases with extension of the range of ECG examinations by vectorcardiography and mapping of electric potentials of the heart on the body surface; echocardiography and scintigraphy may prove valuable).

Keywords: Arrhythmias, Cardiac /physiopathology/; Cardiomegaly /physiopathology/; Cardiomyopathies /physiopathology/; Electrocardiography; Humans; Pre-Excitation Syndromes /physiopathology/