[On the clinical value of electrocardiogram].
Emphasis is given to the clinical value of the electrocardiogram, a simple, quick and unexpensive method for heart exploration. It provides functional information and reliably reflects the metabolic and electrolytic characteristics of myocardial fibers. Such an information cannot generally be obtained by other more sophisticated and expensive methods. The localization and extension of myocardial infarction, the positional and structural changes observed during the evolution of chronic cor pulmonale of obstructive origin, some characteristics of atrial and ventricular arrhythmias, the site of preexcitation in WPW syndrome and troubles due to a dysfunction of the ionic channels because of metabolic or genic alterations, are particularly examined. 1. A good correlation exists between the anatomical site and electrocardiographic indication of the infarcted area. 2. In the obstructive chronic cor pulmonale, positional and structural changes of the heart are observed. The first ones correspond to a vertical heart, due to a descent of the diaphragm and an increase of lung volume. The structural changes are due to an enlargement of the right heart: dilatation and hypertrophy. 3. Ventricular arrhythmias habitually present the "jumping wave" phenomenon between both septal masses and the consecutive aberrance of the ventricular complexes. 4. In the WPW syndrome, the thoracic circle permits to infer the site of preexcitation by the orientation of the first fronts of anomalous ventricular activation. 5. Modifications in the Q-Tc interval reflect the variations of ionic intracellular concentrations in a more reliable way than the changes of plasmatic concentrations. The aforementioned evidences the great usefulness of the electrocardiogram in the clinical setting.