Özet:

Objective: To compare heart rate variability in negative and positive responders to active phase of head-up tilt test. Study Design:Cross-sectional comparative study. Place and Duration of Study: Department of Cardiac Electrophysiology, Armed Forces Institute of Cardiology, Rawalpindi from Jan 2016 to Oct 2016. Material and Methods: Ninety three adult patients of either gender with recurrent unexplained syncope were recruited through convenience purposive sampling. The known cases of diabetes mellitus, cardiac diseases, cardiac arrhythmias and myocardial infarction were excluded from the study. Head-up tilt test was carried out on an electrically driven tilt table. DMS 300-4L Holters were used to obtain ambulatory ECG recordings during head-up tilt test. Cardio scan premier 12 lux software was used for analysis of heart rate variability frequency domain parameters. Results: Total ninety three patients of unexplained syncope were enrolled out of which, 77 (82.8%) patients responded positively and 16 (17.2%) patients gave a negative response. There was significant variation in heart rate variability frequency domain parameters being reduced in positive responders to active phase of head-up tilt test as compared to negative responders. This difference in mean values of heart rate variability frequency domain parameters between positive and negative responders was statistically significant with p-value less than 0.05. Conclusion: The heart rate variability frequency domain analysis done during initial 20 minutes of passive phase of head-up tilt test can predict the results of tests before the administration of drugs.

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