EVALUATION OF BARORECEPTOR SENSITIVITY DURING HEAD-UP TILT TEST IN PATIENTS WITH VASOVAGAL SYNCOPE
The aim of study was an analysis of baroreceptor sensitivity during head-up tilt test (HUTT) in patients with vaso-vagal syncope.
Study population: we observed 240 pts. (78 men, 162 women) aged 18-56 yrs (median of age: 23 yrs) with vaso-vagal syncope (VVS) referred to head-up tilt test (HUTT). Cardio- and neurogenic reasons of syncope were previously excluded in all pts.
Methods: All pts underwent HUTT performed according standard Westminster protocol. Continuous non-invasive monitoring of heart rate (HR) and blood pressure (beat-to beat) was performed using NEXFIN analyser. Based on registered HR and blood pressure values the baroreceptor sensitivity index was calculated both for systolic (BRS-S) and diastolic (BRS-D) blood pressure. We analyse values of baroreceptor sensitivity indexes between pts. with and without HUTT-induced syncope as well as between different types of vasovagal response.
Results: Significant reduction of baroreceptor sensitivity index for systolic blood pressure was observed I patients with positive HUTT in relation to non-fainters (8,6 vs. 21,4 ms/mmHg; p<0,015) whereas there was no significant differences regarding baroreceptor sensitivity index for diastolic blood pressure (15,3 vs. 15,6 ms/mmHg, p=0,85). There were no significant trend thru higher values of BRS-S in patients with cardiodepressive VVS.
Conclusions: Induction of vasovagal syncope during head-up tilt test was concerned with significant reduction of baroreceptor sensitivity calculated for systolic blood pressure.
Impairment of baroreceptor sensitivity seems to play an important role in the patomechanism of vasovagal syncope.