ANP concentrations during interchanging DDD-VVI pacing modes in patients with retrograde ventriculoatrial conduction.

The main reason for the pacemaker syndrome during VVI pacing is the existence of ventriculoatrial conduction (V-AC). Twenty-five patients with a permanent DDD pacemaker and ventriculoatrial conduction were included in the study. IN those patients the hemodynamic changes were evaluated in relation to ANP plasma concentration changes during different modes of pacing. After a resting period of 30 minutes in the supine position ANP plasma concentration and blood pressure were evaluated: a) under DDD atrioventricular pacing at 90/min and for 30 minutes and b) under VVI pacing at 90/min and for 30 minutes. A decrease of systolic blood pressure by 12.77% (P < 0.0001) and diastolic blood pressure by 10.50% (P < 0.0001) was noticed during VVI pacing. ANP was increased during VVI pacing by 215.95% (P < 0.0001). It was observed that the acute transition from DDD to VVI pacing leads to a 3-fold increase in the levels of plasma ANP; this may be partially responsible for the pathogenesis of the haemodynamic changes during VVI pacing mediated through the direct hypotensive effect in addition to the coincidence of atrial and ventricular contraction. This study also proves the role of the increased systolic stress of atrial myocardium for the increased ANP secretion.