Background evaluation of influence of beta-blocker (bisoprolol) on clinical indicators and heart rate variability in children with rhythm disturbances and mitral valve prolapse (MVP).

Material and methods The carried out research has included 50 children, with mitral valve prolapse and rhythm disorders : I group (bisoprolol) 30 (60,0%) children, average age (12,90±0,53) years and II group (placebo) 20 (40,0%) children, average age (13,5±0,60) years, doses of bisoprolol (PO): 1,25–2,5 mg/kg/dose with inspection of haemodynamic and heart rate variability indicators, who were examined with ECG, echocardiography, ECG Holter monitoring over 24 hours, and monitoring blood pressure over 24 hours.

Results The analysis of haemodynamic parametres has revealed, that bisoprolol has not changed average values of systolic and dyastolic blood pressure in the first group in the beginning of research and in dynamics a month later, in comparison with the second group (p>0,05). At patients with MVP, bisoprolol has lowered number of heart rate reductions (−8,9) in dynamics a month later in comparison with placebo (p<0,001). ECG Holter monitoring for 24 hours has defined heart rate average maximum and minimum value in the beginning of research and in dynamics a month later. Dynamics in a month of action of a bisoprolol has not changed the minimum values of heart rate in the first group in comparison with placebo (p>0,05), but has lowered the maximum values of heart rate reductions at children with MVP (−8,74; p<0,01) in the first group in comparison with placebo (0,55; p>0,05) and average values of heart rate (−4,70; p<0,001) in the first group in comparison with placebo (−0,10; p>0,05). Statistical parametres HRV (SDNN and PNN 50) defined in the beginning in both groups did not differ considerably (p>0,05). Dynamics in a month of action bisoprolol on indicators HRV was showed by decrease in value PNN 50 in the first group (−6,42; p<0,001). Spectral parameters of the heart rate variability at children with MVP have been calculated during 24 hours period and there were observed a prevalence of waves with low and very low frequency. Dynamics in a month and 3 months of action bisoprolol there were observed a decrease of spectral parameters with sympathetic vegetative nervous system activity in group I.

Conclusions results of research have revealed, that at children with symptomatic mitral valve prolapse, bisoprolol has considerably reduced heart rate (−8,9; p<0,001) in comparison with placebo, without influence on systolic and diastolic blood pressure. Influence bisoprolol on indicators HRV in the first group it was characterised by decrease by statistics PNN 50 characteristic for activity of sympathetic vegetative nervous system (−6,42; p<0,001). Spectral analysis of the heart rate variability there were observed a decrease of parameters with sympathetic vegetative nervous system activity.