Postural Tachycardia Syndrome (POTS)

Phillip A. Low, M.D.; Paola Sandroni, M.D., Ph.D.; Michael Joyner, M.D.; Win-Kuang Shen, M.D.

Disclosures

J Cardiovasc Electrophysiol. 2009;20(3):352-358. 

In This Article

Abstract and Introduction

Postural Tachycardia Syndrome

Introduction: POTS is defined as the development of orthostatic symptoms associated with a heart rate (HR) increment ≥30, usually to ≥120 bpm without orthostatic hypotension. Symptoms of orthostatic intolerance are those due to brain hypoperfusion and those due to sympathetic overaction.
Methods: We provide a review of POTS based primarily on work from the Mayo Clinic.
Results: Females predominate over males by 5:1. Mean age of onset in adults is about 30 years and most patients are between the ages of 20–40 years. Pathophysiologic mechanisms (not mutually exclusive) include peripheral denervation, hypovolemia, venous pooling, β-receptor supersensitivity, psychologic mechanisms, and presumed impairment of brain stem regulation. Prolonged deconditioning may also interact with these mechanisms to exacerbate symptoms. The evaluation of POTS requires a focused history and examination, followed by tests that should include HUT, some estimation of volume status and preferably some evaluation of peripheral denervation and hyperadrenergic state. All patients with POTS require a high salt diet, copious fluids, and postural training. Many require β-receptor antagonists in small doses and low-dose vasoconstrictors. Somatic hypervigilance and psychologic factors are involved in a significant proportion of patients.
Conclusions: POTS is heterogeneous in presentation and mechanisms. Major mechanisms are denervation, hypovolemia, deconditioning, and hyperadrenergic state. Most patients can benefit from a pathophysiologically based regimen of management.

Introduction

Orthostatic intolerance is defined as the development of symptoms of cerebral hypoperfusion or sympathetic activation while standing that is relieved by recumbency. Patients with orthostatic intolerance often present with complaints of exercise intolerance, lightheadedness, diminished concentration, tremulousness, nausea and recurrent syncope, and may be incorrectly labeled as having panic disorder or chronic anxiety.[1] Simple activities such as eating, showering, or low-intensity exercise may profoundly exacerbate these symptoms and may significantly impair even the most rudimentary activities of daily living. Somewhat paradoxically, the magnitude of these symptoms is often significantly greater than those observed in patients with obvious clinically detectable autonomic failure.

Although neurogenic orthostatic hypotension (OH) due to the autonomic neuropathies, such as those of diabetes and amyloidosis, and nonneuropathic disorders such as MSA (multiple system atrophy; Shy-Drager syndrome) and PAF (pure autonomic failure; idiopathic orthostatic hypotension) are better known, these disorders are relatively uncommon. Most patients with orthostatic intolerance do not have florid autonomic failure and do not have OH. Improved recognition of lesser degrees of orthostatic intolerance came with the observation that the most common and the earliest manifestation of orthostatic intolerance is an excessive tachycardia.[2] These subjects have disorders that are sometimes termed "benign" disorders of reduced orthostatic tolerance. The unifying feature is the development of orthostatic symptoms without consistent OH. Investigators and clinicians have been impressed with different aspects of the conditions and have approached orthostatic intolerance from different perspectives. Terms such as effort syndrome, neurasthenia, idiopathic hypovolemia,[3] sympathotonic orthostatic hypotension, emphasizing sympathetic overactivity,[4] and mitral valve prolapse syndrome[5] exemplify the concentration on particular components of the patient's disease. Postural tachycardia ± syncope can be present in several of the disorders. Some patients with chronic fatigue syndrome have orthostatic intolerance with tilt-induced syncope, and a subset will respond to treatment directed at syncope.[6]

We have focused on orthostatic tachycardia since an excessive HR increment appears to be the earliest and most consistent of the easily measured indices of orthostatic intolerance.[7] Most of the other terms focus on manifestations that are not consistently present. The term idiopathic hypovolemia is unsatisfactory, since most patients do not have reduced plasma volumes or red cell mass. Current thinking is that the occurrence of mitral valve prolapse with POTS is fortuitous. The emphasis on postural tachycardia does, however, have a disadvantage in that it ignores nonorthostatic symptoms such as paroxysmal episodes of autonomic dysfunction, including sinus tachycardia, BP fluctuations, vasomotor (especially acral) symptoms, and fatigue.

The prevalence of POTS is unknown. In clinical practice, it is probably about 5–10 times as common as orthostatic hypotension. One estimate is the prevalence is at least 170/100,000.[8] This is based on the investigators' documentation that 40% of patients with chronic fatigue syndrome have POTS.

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