Abstract
Background: Autonomic failure is an integral component of Parkinson’s disease (PD), and orthostatic hypotension (OH) is commonly observed in advanced cases of PD. OH may be the result of underlying cardiovascular autonomic dysfunction or adverse effect of antiparkinsonian drugs. Patients may be asymptomatic during the early stage of disease but may have underlying cardiovascular dysautonomia which becomes obvious on stress. Most of the earlier studies used morphological and functional methods to evaluate cardiovascular autonomic control but were unable to evaluate during dynamic conditions.

Aims and Objectives: The aim of the study was to evaluate cardiovascular autonomic disturbances in patients with PD using head-up tilt table test (HUTT). The objective of the study was to compare the spectral profile of heart rate variability (HRV) and blood pressure (BP) to orthostatic challenges using HUTT in patients with PD with healthy individuals.

Materials and Methods: In this cross-sectional study, we have recorded continuous lead II ECG along with BP every 2 min in patients with PD and control group during HUTT for 10 min in supine, 45 min in 70° tilt and again 10 min in supine position which were later analyzed using Biopac software for HRV.

Results: Symptoms indicating autonomic nervous system dysfunction were present in 65% (20) patients with PD. Postural dizziness was present in 20% (6) patients. After 5 min of tilt-up, increase in HR in patients with PD was lower than in controls. There was no significant change in diastolic BP (DBP) on tilting-up in patients with PD while DBP significantly increased in controls on tilting-up from73 ± 9 mm Hg to 80±11 mm Hg (P < 0.00001). The low frequency (LF) was not significantly changed in patients with PD, and it increased significantly in controls from 3.05 (2.28 to 4.70) ms2 to 3.73 (2.69–5.03) ms2. There was decrease low frequency/high frequency (LF/HF) in patients with PD, but the change was not significant, and there was a significant increase in LF/HF ratio from 3.43 (3.15 to 4.02) to 5.01 (4.39–5.74) in control group (P < 0.00001).

Conclusions: Patients with PD suffered from symptoms of autonomic dysfunction and had cardiovascular autonomic dysfunction which becomes obvious only during stress. This will help clinicians to identify the patients of PD with cardiovascular autonomic dysfunction at an early stage and modify the treatment accordingly to prevent frequent falls.

Key words: Parkinson Disease; Autonomic Dysfunction; Heart Rate Variability; Tilt-table Test