[Electrocardiography in pediatrics. 1: Critical considerations of methods and experimental findings].

: The results of experimental cardiology are reported on the basis of the electrophysiology of the heart. The QRS complex of the ECG, representing the spread of excitation through the ventricles, is used as an example to reflect the physiological and pathological events of the heart. The limitations of this example arise from the uncorrected recordings of the potential differences from the body surface. The need to use corrected lead systems is pointed out. The most commonly used FRANK lead system is extremely sensitive to the inaccurate positioning of lead points on the thorax. Evidence for this drawback is given by experimental findings in infantile and juvenile rats. It is clear that inaccurate positioning of electrodes is especially crucial in small subjects. A fundamental criticism of the FRANK lead system used in growing subjects is the impossibility of eliminating the errors caused by the changing geometry of the thorax of children of different ages. Improvement of the physical correction of ECG recordings in children for the purpose of reliable diagnostics is vital.