[Relationship between ventricular extrasystole and parasystole]

Monomorphic ventricular extrasystoles, no less than 30 within an hour, were revealed in 89 of 300 patients with chronic ischemic heart disease during continuous 24-hour ECG recording on magnetic tape. A fixed type of the linkage interval (oscillations of no more than 0.1 sec) was established in 58 (62%) and the variable tupe (oscillations of more than 0.1 sec) in 31 (38%) patients. Oscillations in the linkage interval of more than 0.1 sec gave grounds to suspect parasystole. A deeper analysis revealed parasystole in 8 cases (2.6% of the total number of patients), the remaining cases were included in the group of extrasystoles with a variable non-parasystolic type of the linkage interval. This group of extrasystoles occupies an intermediate position between para- and extrasystole. The large number of transitional forms between extra- and parasystole suggests their common origin.