Objective: To determine whether isovolumic relaxation flow (IRF) and isovolumic contraction flow (ICF) resulted from asynchrony and asynergy due to VVI and DDD pacemakers modulated neurohormones, we measured neurohormone levels in plasma and investigated the characteristics of IRF and ICF using Doppler echocardiography.
Methods and results: We studied 11 patients with dual-chamber pacemakers (DDD) and 11 patients, with ventricular inhibiting mode (VVI). All patients underwent Doppler echocardiography of the left ventricle. Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), renin and aldosteron were measured. The LV was scanned for the presence of intracavitary flow during the isovolumic relaxation and isovolumic contraction period. The plasma levels of BNP and ANP were significantly lower in DDD mode than in VVI mode (56 +/- 32 pg/ml vs. 94 +/- 32 pg/ml, p = 0.022 and 98 +/- 20 pg/ml vs. 134 +/- 17 pg/ml, p = 0.042, respectively). There were no significant differences in the plasma level of renin or aldosteron. VVI mode versus DDD mode increased isovolumic relaxation flow time (129 +/- 41 vs. 111 +/- 36 sec, p = 0.020) and isovolumic relaxation flow velocity (50 +/- 4 vs. 37 +/- 2 cm/s, p = 0.018). A strong relationship between blood ANP and BNP levels and IRF velocity was found in patients with a VVI pacemaker (r: 0.632, p: 0.028; r: 0.528, p: 0.024, respectively).
Conclusion: VVI mode has a longer isovolumic relaxation time, isovolumic relaxation flow velocity and has higher ANP and BNP plasma levels than DDD mode. IRF resulting from asynergy and asynchrony in VVI mode pacemakers versus DDD mode pacemakers affects the plasma levels of ANP and BNP compared to renin and aldosteron.