IRREGULAR SINUS PARASYSTOLE DUE TO INTERMITTENCY AND MODULATION OF PARASYSTOLIC ACTIVITY

A case of intermittent sinus parasystole in which the parasystolic foc us is protected from the dominant sinus rhythm only during the second half of its intrinsic cycle is reported, In addition, a modulating (i, e,, electrotonic) effect is often clearly exerted from the dominant rh ythm upon the focus during the protected period, Coexistence of both m odulation and intermittency in sinus parasystole, as well as a modulat ing effect limited to the second part of the parasystolic cycle, have not been previously reported.