I.V. Shanina, D.E. Volkov, N.I. Yabluchansky. Changes of permanent pacing parameters in patients with implanted pacemakers depending on QRS complex duration at six months follow-up

66 patients (26 women, 40 men) with permanent pacemakers due to atrio-ventricular block II and III degrees, mean age 69±7 years were examined. Patients were divided into three groups depending on QRS complex duration: under 120 ms (normal), 120–149 ms (extended) and 150 and more ms (significantly extended). The programmer was used to define the basic pacing rate, atrioventricular delay (stimulated and detected), ventricular threshold and ventricular lead impedance, percentage of ventricular pacing, atrial fibrillation time percentage. Basic pacing rate, ventricular threshold, atrioventricular delay, the percentage of ventricular pacing in did not change in any group at six-month period of observation. Ventricular lead impedance decreased, and its rate of decrease was the largest in patients with increased QRS complex duration. Percentage of atrial fibrillation time was higher at the beginning of pacing in patients with significantly extended QRS complex. It gradually decreased during follow-up but didn’t reach the levels in patients with lower QRS complex duration where they remained almost at the same level.

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