Tachycardia | Pathophysiology of Orthostatic Intolerance

Tachycardia research study

What is the primary objective of this study?

The purpose of this study is to describe the mechanism of orthostatic intolerance, relying on cardiovascular physiological studies. The syndrome is of undetermined etiology, but the syndrome causes impairment of a number of young adults, females more than males, with symptoms of tachycardia, fatigue, lightheadedness, palpitations, blurred vision, chest discomfort, difficulty concentrating, and dizziness with the upright posture. It is believed that many different pathophysiological processes can give rise to this disorder.

Who is eligible to participate?

Inclusion Criteria: - Orthostatic intolerance Exclusion Criteria: - Inability or unwillingness to give informed consent

Which medical condition, disease, disorder, syndrome, illness, or injury is researched?


Postural Orthostatic Tachycardia Syndrome

Study Interventions

Interventions can include giving participants drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available or noninvasive approaches such as surveys, education, and interviews.

Radiation:DAXOR131-I-Human Serum Albumin Blood Volume Assessment Kit

Procedure:QSweatQuantitative Sweat Testing

Drug:Intrinsic Heart RateAtropine 0.04 mg/kg IV in divided doses Propranolol 0.2 mg/kg IV in divided doses

Study Arms

Research studies and clinical trials typically have two or more research arms. An arm is a group of people who receive the same treatment in the study.

PatientsPatients with orthostatic intolerance

Healthy Control SubjectsHealthy subjects to determine "normal" response

Study Status


Start Date: December 1996

Completed Date: December 2019

Phase: N/A

Type: Interventional


Primary Outcome: Physiological abnormalities in orthostatic intolerance

Secondary Outcome: blood volume

Study sponsors, principal investigator, and references

Principal Investigator: David Robertson, MD

Lead Sponsor: Satish R. Raj

Collaborator: National Institutes of Health (NIH)

More information:

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