[Changes of parameters of hemodynamics and systems of neurohumoral regulation in patients with implanted cardiac pacemakers after switching from DDD to VVI pacing mode].

To study complex of pathogenetic changes arising during VVI mode single chamber ventricular pacing we temporarily (for 1 hour) switched pacing mode from dual (DDD) to single (VVI) chamber stimulation in 11 patients. Parameters studied were cardiac output (CO), total peripheral vascular resistance (TPVR), levels of precursors of atrial and inactive fragment of brain natriuretic peptides (pro-ANP and NT-pro-BNP, respectively), noradrenaline, aldosterone, and renin activity in blood plasma. Reprogramming of pacing mode was associated with 21.4% lowering of CO and 11.4% elevation of TPVR according to impedance cardiography data, and augmentation of pro-ANP secretion from 429.79 to 620.22 fmol/l. At the background of VVI pacing there was a tendency to increase of noradrenaline blood concentration without significant changes of aldosterone concentration and plasma renin activity.