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Background: The crucial step in prevention of sudden cardiac death (SCD) is a method of a precise and most accessible identification of those patients with ischaemic cardiac disease (ICD), especially after MI, who are highly presumptive candidates of malign ventricular arrhythmias. The selection of individuals exposed to risk, and individual judgment of the threat to patients after MI is a complex problem. Patients after MI are endangered by reinfarction, cardiac failure, heart wall rupture and primary ventricular tachyarrhythmia. Stratification of patients exposed to a presumably higher risk of probable new coronary event and malign ventricular arrhythmia with an early decision to intervene, gains practical clinical significance. Similarly, it is important to identify also the patients after MI exposed to lower risk, who need no interventional therapeutical procedure. The cardiologic practice utilizes several examinatory procedures and tests, prevailingly of non-invasive character., Aims and Objectives: The study reviews the latest information on pathophysiology and current level of clinical interpretation of non-invasive ecg procedure from the field of high-resolution electrocardiography including the late ventricular potentials (LVP). The study is aimed at: a) presentation of a review of available information from the field of electrophysiology and clinical electrocardiography and the mechanism of impact of myocardial ischaemia on the existence of high-frequency, but at the same time extremely low-amplitude potentials abnormalities in the course of QRS complex and S-T segment (LVP), b) presentation of a review on the informative value and clinical significance produced by non-invasively detected electrophysiological heterogeneity of myocardium during ischaemia, aiding the short-term and long-term prognosis judgments in patients with ICD, especially after undergoing its most serious form--myocardial infarction. Beside the group analysis the study is also aimed at individual non-invasive judgment of risk of the development of malign ventricular arrhythmias in patients with acute coronary syndromes. (Fig. 3, Ref. 41.)

Experiences with the determination of the preexcitation focus in 13 patients with W-P-W syndrome aged 18-62 years are presented. The data of ECG mapping from the chest surface and the abdominal wall were processed by computer. For classification of the maps the criteria elaborated by Yamada et al., da Ambroggi et al., and Benson et al. were used. It was possible to determine on their basis the preexcitation focus in all examined subjects, although a reduced system of ECG leads was employed. Surface ECG mapping makes possible a more precise location of the preexcitation, which is of great clinical importance for the indication of surgical treatment, determination of prognosis and of working ability.

Electrocardiographic methods play a decisive role in evaluation of the health condition of subjects with WPW pattern. The authors examined 54 patients with WPW pattern with different degrees of preexcitation. The presence of preexcitation and the localization of its focus was determined by surface electrocardiographic mapping using the original Czechoslovak computer equipment KARDIO-SMEP 01.0. The duration of ventricular activation was determined according to root mean square signals. By means of potential and temporo-spatial analysis of peak negative regions of instantaneous maps (in 2 ms intervals) they determined the duration of the period of proper preexcitation, of fusion of the two activation events, and of the end depolarization of the ventricles. In localizing the preexcitation focus they proceeded according to the criteria of Benson et al. (1982) with individual evaluation of quantitative preexcitation parameters of ECG maps and according to vector analysis of the delta wave. Quantitative and temporo-spatial evaluation of the mutual relationship of the two activation events in WPW pattern allows to establish reliably the presence, degree and focus localization of preexcitation even at a low degree of preexcitation and at a low-potential level of the preexcitation surface activity on ECG maps.

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).