Acute and chronic changes in atrial natriuretic factor induced by ventricular pacing: a self controlled clinical...

A self controlled clinical trial was carried out to study the acute and chronic effects of ventricular pacing (VVI) on the atrial natriuretic factor (ANF). Eleven people were selected from a pool of 20 DDD paced patients. Pacemakers were programmed to the VVI mode for 1 month and their effectiveness tested by ECG at rest and after an effort test. AnF was measured by radioimmunoassay at baseline, after 15 minutes, and again 1 month after programming. The reliability of the radioimmunoassay was confirmed using the coefficients of variation between (12.5%) and within assay (9.7%). Data analysis was done using Wilcoxon's test. Our results showed that the onset of VVI pacing led to a sudden sharp rise in ANF in all patients (P < 0.0001). During VVI pacing, three patients were dropped from the study (2 were withdrawn because of symptoms and 1 voluntarily withdrew). After 1 month of VVI pacing, a significant increase of ANF above the baseline was observed (P < 0.05). The results showed that ventricular pacing led to an immediate rise in ANF and, that with long-term VVI pacing, there was an increase in ANF levels as well. The role of these findings in the pathophysiology of the pacemaker syndrome calls for further research.