The aim of this study was to estimate the usefulness of ECG Holter Monitoring (HM) in the detection of asymptomatic stimulation disturbances in patients with VVI pacemakers and normal pacemaker function during routine ECG. We retrospectively examined 424 patients, who had an implanted artificial pacemaker between 1992-1994. The examined patients were divided into two groups according to HM indications: group 1 (asymptomatic) - 360 patients (85%) referred for assessment of antiarrhythmic therapy; group 2 (symptomatic) - 64 patients (15%) with a history of fainting or loss of consciousness. We found stimulation disturbances in 35 patients (8%), 25 patients (6.9%) from group 1 and 10 (15.6%) from group 2. Amongst the 35 patients with stimulation disturbances we noted muscular inhibition in 19 patients, periodic ineffective stimulation in 10 and transient disturbances of sensing in 6 patients. Conclusions: 1. 24-hour Holter monitoring is a valuable diagnostic method in the detection of stimulation disturbances in asymptomatic and symptomatic patients with implanted VVI unipolar pacemakers. 2. Stimulation disturbances occurred twice more frequently in symptomatic than in asymptomatic patients. 3. In 7.5% of patients suffering from syncope or loss of consciousness we noted stimulation disturbances.

Keywords: asymptomatic stimulation disturbances, Holter monitoring, VVI pacemakers