[Methods of recording late ventricular potentials as a basis for their rational clinical use]

The risk of development of ventricular arrhythmias can be evaluated at present also by examination of late ventricular potentials. Late ventricular potentials are high-frequency low-amplitude signals which develop in the terminal part of the QRS complex and are the manifestation of retarded excitation in the myocardial area where islets of vital muscle alternate with islets of fibrosis and/or necrosis. Their detection is very pretentious as regards recording and processing of the electrocardiographic signal. Only relatively complicated procedures ensure that the result of the examination has a clinically acceptable sensitivity and specificity. These procedures are not "observed and appreciated" by the majority of workers because they are "hidden" in the instrumental technique which is used. The objective of the submitted paper is to focus attention of clinicians on the frequently omitted aspect of examinations of late ventricular potentials--its technical prerequisites. The author did not focus attention on complicated mathematical formulations which are the basis of processing of the signal but tried to concentrate on the link between the technical aspect and clinical consequences. Similarly as in other examinations based on the latest technique, also in this case the effect depends to a considerable extent on the knowledge of usable and technical procedures applied in a given case. Unless we are aware of these facts the clinician becomes a mechanical consumer of results of examinations and is restricted to the simplest level of interpretation. The objective of the paper is moreover to remind that it is not possible to adopt and compare uncritically the results of investigations implemented under different technical conditions.