In patients with aortic stenosis, reduced cardiac output may increase sympathetic nerve activity. However, the magnitude of the increase in sympathetic activity in such patients and the effect of valve replacement (VR) on this activity are unknown.
In this preliminary study, we prospectively included 24 patients (mean age=76,0±8,7 years) with severe aortic stenosis (defined for <0,60cm2/m2). Holter-EKG recording (lasting 24hours) allowed heart rate variability analysis (temporal and spectral parameters) and QT dynamicity calculation. The latter was assessed by plotting QT and RR intervals to obtain a liner characterized by its slope linear. 24-h Holter recordings, clinical, biological and morphological data were collected before and after aortic valve eplacement.
Valve replacement induced a significant improvement in cardiac output. Holter EKG parameters evaluating the sympathetic nervous system activity showed a decrease of SDNN, VLF and LF. Hence, SDNN/5mn, eflecting sympathetic modulation of heart rate, calculated on 24hours significantly decreased after aortic valve replacement (42,1±25,0 to 27,27±24ms; p<0,05). Significant changes of EKG parameters are summarized in table below (* for p<0.05). None of parameters evaluating QT dynamicity were significantly modified after aortic valve replacement.
This study shows for the first time the beneficial effect of aortic valve replacement on the sympathetic nervous tone. We plan to follow up these patients and assess occurrence of cardiovascular complications (i.e. Heart failure, atrial fibrillation). Complimentary results will allow us to identify SNS measurement.
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