Orthostatic Intolerance Differential Diagnoses

Updated: Nov 13, 2019
  • Author: Julian M Stewart, MD, PhD; more...
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DDx

Diagnostic Considerations

Low risk patients with no heart disease may have a diagnosis of vasovagal syncope (VVS) established on history, which is characteristic. However, until cardiovascular risk has been established by a cardiologist the diagnosis of VVS is not certain. Asystolic VVS occurs and data from adults suggest the utility of pacing such patients in order to reduce morbidity. No such data exist in young people. However, asystolic VVS requires loop recording either external or internal to ascertain the diagnosis. A 24-hour ambulatory monitor will not suffice.

In general, the diagnosis of orthostatic intolerance other than VVS requires some validated form of orthostatic stress test. Moreover, not all OI is VVS or postural tachycardia syndrome (POTS); the definition of OI is left vague on purpose to include a wide range of symptoms or signs that are relieved by recumbency.

If the patient fits the definition of orthostatic intolerance, then they have OI. If symptoms initiate while supine and intensify then they are likely to have another etiology. Symptoms present in all body positions are not OI.