Influence of AV synchrony on the plasma levels of atrial natriuretic peptide (ANP) in patients with total AV block.

ANP was determined in 13 patients with DDD pacemakers due to total AV block, at rest and during bicycle ergometry under both pacing modes, DDD and VVI (7O/min). Under DDD pacing, the mean ANP level (normal range 5-95 pg/mL) at rest was 36 +/- 18 pg/mL (mean +/- SD) and increased significantly by the factor of 3.5 to 1 27 pg/mL during exercise (p less than 0.01). By just changing the pacing mode to VVI, the ANP levels rose to 73 +/- 28 pg/mL (p less than O.0 1) at rest (= 203% of DDD resting level) and to 216 +/- 184 pg/mL (= 170% of DDD peak level) during exercise P less than 0.01). These results show that under AV synchronous pacing, the ANP levels we generally lower. A possible explanation for this increased release of ANP during asynchronous VVI pacing is the acute increase of the atrial wall tension which occurs when the atria contacts during the systole against closed AV valves.