ELECTROCARDIOGRAPHIC SIGNS OF DISTURBANCE S OF MONOPOLAR PACING OF THE HEART

ECG recordings and results of pacemaker function tests from 32 patient s with cardiac pacemaker malfunction were used for the study of electr ocardiographic signs of stimulation disturbances due to various causes . Dislocation and microdislocation of an endiocardial lead were charac terized by persistence of registration of high amplitude (up to 2 mV) stimulus artifacts during complete or partial loss of capture. Endocar dial lead dislocation in approximately half of cases resulted in decre ase of sentivity of a pulse generator and disturbances of synchronizat ion function. According to VARIO test microdislocation led to progress ive elevation of stimulation threshold while synchronization function remained intact. When stimulation theshold was high progressive attenu ation of a stimulus artifact occurred. This was followed by conversion to asynchronous pacing mode and eventually by cessation of stimulatio n.