Palpitations ––When to Worry

Postural Orthostatic Tachycardia Syndrome

Being female protects us from early atherosclerotic heart disease. However, there are some clinical conditions that seem to afflict women in a greater proportion than would seem appropriate. One group of diseases includes those of autonomic regulation, among them Postural Orthostatic Tachycardia Syndrome (POTS), considered to be a part of the autonomic nervous system dysfunction that includes vasovagal syncope.

In 1944, the first descriptions of a clinical syndrome, which involved orthostatic intolerance, inappropriate tachycardia, and often disabling fatigue, began. Sporadically, over the years, case reports were u\published, and attributed to neurasthenia and various other mechanisms. Unfortunately, many of the patients affected by this problem were considered, frankly, nuts. However, this is an autonomic dysfunction, where inappropriate catecholamine responses occur, which is very difficult to treat, and seems to have a female predominance. There may also be a crossover with chronic fatigue syndrome, and in fact, in one of the reports on using tilt table testing to evaluate children with chronic fatigue syndrome six of the seven patients were female.

In a series by Grubb (PACE, 1997), 26 of 28 patients with POTS were female. In many of these cases, the symptoms began after a viral infection, and 3 were associated with endocrine changes, including post-partum and menopausal state. Many of the patients had gastrointestinal symptoms and in some cases delayed gastric emptying was demonstrated. With tilt testing, venous pooling, inappropriate sinus tachycardia and hypotension were noted. The response to low dose isoproterenol was a heart rate increase, on average, of nearly 40 beats per minute. This also evoked severe symptoms, even though most of the patients did not faint. The most effective therapy in this group appeared to be fludrocortisone, even though this agent was often combined with beta-blockers or serotonin reuptake inhibitors.

In summary, POTS appears to be an autonomic disorder characterized by inappropriate catecholamine response to orthostatic stress, often triggered by viral illnesses or other physiologic stressors, and with a particular female preponderance. Its confusion with psychiatric disorders has led to incorrect diagnoses including anxiety neurosis and panic attacks. However, since serotonin reuptake inhibitors can be effective therapy for POTS, many patients may receive partially or completely effective therapy without a correct diagnosis.

_{Related links:

Cardiac Arrhythmias: Why Women are Different from Men

Palpitations –– When to Worry}

This page was contributed by Lou-Anne M. Beauregard, M.D., cardiologist and electrophysiologist who is in private practice in Manalapan, NJ

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