Τόμος 10 (1992) – Τεύχος 4 – Άρθρο 3 – Επιθεώρηση Κλινικής Φαρμακολογίας και Φαρμακοκινητικής-Ελληνική Έκδοση – Volume 10 (1992) – Issue 4 – Article 3 – Epitheorese Klinikes Farmakologias και Farmakokinetikes-Greek Edition

10: 217-221 (1992)

PHARMAKON-Press: Epitheorese Klin. Farmakol. Farmakokinet.

10: 217-221 (1992)

Ventricular tachycardia, electrophysiologic study

The aim of electrophysiological study (EPS) in patients with suspected or clinical ven­tricular tachycardia is a) to confirm the appearance of the above arrhythmia, b) to elucidate the possible starting mechanism and perpetuation of arrhythmia, c) to study the behaviour of arrhythmia after having induced electric stimuli or after given antiarrhythmic drugs. The patients who need EPS may be divided in three groups according to the type of the arrhythmia and the presence of cardiac disease. This type of EPS comprises of pro­grammed cardiac pacing of the Right and Left Ventricle with extrastimuli and simultaneous multiple endocavitary and surface recordings, in an attempt to initiate ventricular arrhythmia and to record evidences of the possible mechanisms or the areas of arrhythmiα initiation. Also, by scanning of the diastolic phase of arrhythmia cycle length with extrastimuli, one is able to estimate the behaviour of the tachycardia. The EPS results are different in the above three groups of patients and have direct relationship with the underlined heart disease, the degree of ventricular dysfunction and, possibly, the mechanism of in­itiation of arrhythmia. Also, the EPS results are directly dependent on the patients’ population under study and on the “aggressiveness” of the stimulation protocol, although the initiation of polymorphic sustained ventricular tachycardia with art “agressive” EPS protocol is an event without any meaning. In patients having myocardial in­farction the Electrophysiological Study may reveal a potential reentry circuit with short refraction periods capable of serving as a substrate for sustained monomorphic ventricular tachycardia after the patient receives any drugs that may prolong the refractoriness. This helps to avoid the use of such a drug in this category of patients. The initiation of sustained monomorphic ventricular tachycardia in the above patients ident­ifies a high risk group for arrhythmic events, while it is difficult to induce the above arrhythmia in patient with normal myocardium. The response to programmed electrical stimulation of the heart reveals inducible VT and/or VF in 80 to 90% of patients suggesting a reentry mechanism for the arrhythmia. Apart from any doubt, the EPS may be predictive of impending events of sudden death or sustained ventricular tachycardia and any treatment based on EPS is pretty successful. For the above reason the number of patients subjected in EΡS is constantly increasing.

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