Acute and Chronic Changes in Atrial Natriuretic Factor Induced by Ventricular Pacing: A Self Controlled Clinical Trial

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 WI 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 During VVI pacing, three patients were dropped from the study (2 were withdrawn because of symptoms and 1 voluntarily withdrew).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 WI 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.