Delayed Orthostatic Hypotension: A Pilot Study from India

Introduction: Orthostatic hypotension is defined as a sustained decrease in systolic blood pressure of 20 mm Hg or a decrease in diastolic blood pressure of 10 mm Hg within three minutes of standing compared with blood pressure from the sitting or supine position or by head-up tilt-table testing (1). When sustained blood pressure (BP) drop is after three minutes of upright posture it is called delayed orthostatic hypotension (delayed OH) (2).

Aim of the study: To detect the incidence of delayed orthostatic hypotension in patients referred to our autonomic lab.

Materials and method: BP was measured noninvasively at 1-minute intervals with an automated cuff sphygmomanometer over the right brachial artery for 45 minutes. The onset and duration of falls in blood pressure either systolic or diastolic or both were documented, and any associated symptoms were recorded. Only patients with sustained falls in BP were included. Drugs causing OH was stopped 48 hours before testing as per protocol followed in lab. We also looked into other autonomic function test abnormalities in patients with delayed OH.

Inclusion criteria: Patients above age of 18 years referred for evaluation of autonomic function tests.

Exclusion criteria: Patients with severe cardiac failure and cardiac arrhythmias were excluded and patients with rapid fall in BP and bradycardia (Neurally mediated syncope) were excluded.

Results: Total 170 patients underwent tilt table testing. Orthostatic hypotension was seen within 3 minutes in seventy patients, fifty patients had delayed OH (BP fall after 3 minutes). There were twenty seven males and twenty three females in this group. Twenty nine of the 50 patients with delayed orthostatic hypotension, had symptoms during the tilt table procedure. Asymptomatic OH was more common in patients who developed OH after 10 minutes.

Conclusion: This is a pilot study, first in India where we looked into the incidence of delayed orthostatic hypotension in patients undergoing tilt table testing in our autonomic lab. We found that fifty patients had delayed orthostatic hypotension which could have been missed on clinical evaluation. High clinical suspicion is needed to detect this disorder and tilt table testing should be done in suspicious cases since orthostatic hypotension is cause of high morbidity.