Research in review

• Postural syncope: mechanisms and management
• POTS: An underrecognized disorder
• POTS during Pregnancy
• Disturbed sleep and equality of life in patients with POTS
• ‘Early’ vs ‘Late’ Pots
• Salt and Caffeine: Good or Bad?

Postural syncope: mechanisms and management

Vaddadi G, Lambert E, Corcoran SJ, Esler MD.
Baker Heart Research Institute, Melbourne, VIC, Australia. gautam.vaddadi@baker.edu.au

Postural syncope is a transient loss of consciousness secondary to a reduction in cerebral blood flow and is typically precipitated by standing. It is the commonest cause of recurrent transient loss of consciousness. Recurrent unexplained postural syncope is most often due to one of the five disorders of circulatory control: vasovagal syncope, postural tachycardia syndrome, chronic autonomic failure, initial orthostatic hypotension, or persistently low supine systolic blood pressure. Failure to identify the underlying cause of postural syncope can result in ongoing morbidity, impaired quality of life and high health care costs. With a detailed history, examination, blood pressure assessment and electrocardiography, most disorders of circulatory control can be diagnosed. In difficult cases, analysis of sympathetic nervous system and circulatory responses during head-up tilting can aid diagnosis. Treatment is challenging and compounded by a lack of evidence. Most patients can be managed in an outpatient setting, and hospital admission or emergency department assessment is rarely warranted.

PMID: 17767437

Intern Med J. 2007 Aug;37(8):529-35. Epub 2007 Apr 16.

POTS: An underrecognized disorder

Pandian JD, Dalton K, Henderson RD, McCombe PA.

Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.

BACKGROUND: Postural orthostatic tachycardia syndrome (POTS), a clinical syndrome of orthostatic intolerance characterized by excessive tachycardia and symptoms of cerebral hypoperfusion on standing, is not well recognized in Australia. The aim was to study the clinical symptomatology, results of autonomic testing and outcome in patients with POTS.

METHODS: Sixteen subjects from a tertiary referral centre who met the criteria for POTS were studied between January 2003 and January 2006. Ten of these patients consented to be interviewed using a validated autonomic symptom questionnaire. Heart rate responses to deep breathing and the Valsalva manoeuvre were measured using Colin BP-508 machine (WR Medical Electronic Co., Stillwater, MN, USA). Tilt studies were carried out for 10 min to 80 degrees of head-up tilting. Patient outcome was assessed as functionally normal, able to stand 30 min without symptoms, able to work and carry out recreational activities or worse on follow up.

RESULTS: The mean age of 10 subjects was 24.9 +/- 6.8 years, six being women. The mean duration of symptoms was 70.7 months (range 3-228 months). The common presenting orthostatic symptoms were light-headedness (100%), palpitations (90%), pallor (90%), weakness (80%) and clammy skin (80%). The mean heart rate increment during the tilt study was 51.7 +/- 14.3 b.p.m. The mean duration of follow up was 8.9 months (range 1-16 months). Only five patients were functioning normally at the follow-up visit.

CONCLUSION: POTS is an underrecognized but persistent autonomic disorder in young patients with a variety of symptoms and variable outcome.

PMID: 17445012

POTS during Pregnancy
by Heather Thompson*

POTS is a fairly new finding so there is limited information on POTS and pregnancy. Most patients have managed very well during pregnancy and delivery. Patients typically do well during pregnancy and sometimes even feel better than when they weren’t pregnant.

One thing that you must remember is that the patient shouldn’t be on any medications during their pregnancy. Although sometimes physicians will allow patients to stay on beta blockers.

The information found so far while researching this topic is that one, the patient needs to be at a point where they feel well enough that they can manage without taking any medications. The patient should also be on a high salt, high fluid regimen. The pregnancy should be managed as a high risk pregnancy by their OBGYN.

During delivery physicians need to ensure that the patient is volume expanded and also remember that the patient should not undergo prolonged labor.
The main things the patient must realize that they may feel worse after the delivery when their symptoms may return.

*Information used within this article was taken from an article by Dr. Phillip A Low, M.D.

Disturbed sleep and equality of life in patients with POTS
by Heather Thompson*

There have been numerous amounts of studies done on the topic of sleep. The below paragraph is a brief conclusion on what has been found so far:

There is excessive daytime sleepiness and a significant reduction in the quality of sleep in postural tachycardia syndrome. This is associated with a marked increase in fatigue and a significantly lower quality of life. The cause of these sleep problems might relate to patients in some ways because POTS patients tend to have a higher or elevated adrenaline. Further research is currently being done to find out more about the underlying pathophysiology.

*Research done by the Department of Medicine, Vanderbilt University, Nashville, TN, USA

‘Early’ vs ‘Late’ Pots
by Heather Thompson*

Traditional diagnosis of POTS involves a rise in heart rate by 30 beats per minute or to 120 beats per minute within the first 10 minutes of head-up tilt. However, a rise in heart rate after 10 minutes is very frequently seen. It is unknown if there is a physiologic difference between an ‘early’ (within 10 minutes) vs ‘late’ (after 10 minutes) rise in HR in those with POTS. Blood volume and hemodynamic testing of venous pooling and circulatory kinetics is used to further investigate the diagnosis found during head-up tilt.

Conclusion: Significant differences were found between ‘early’ and ‘late’ POTS patients, suggesting that there are two distinct entities based on different mechanisms. The implications for therapy are still unknown at this time, but there is further research going on to study this issue.

*Research conducted by K.A. Mayuga, K. Butters, F. Fouad-Tarazi-Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, OH, USA

Salt and Caffeine: Good or Bad?
by Heather Thompson*

One of the more important factors to prevent reduction in blood pressure when standing up is to have an adequate blood volume. Two of the most important factors of maintaining normal blood volume that you can control are an adequate intake of salt and fluids. People with orthostatic intolerance are very sensitive to reduced blood volume. The reason salt is so important is due to the fact that sodium ions are retained in the blood, which helps ensure a normal blood volume. Excessive salt is then passed in urine.

Caffeine is a drug that raises blood pressure. For example, two cups of strong coffee contains around 250 mg of caffeine. This dose is adequate to raise blood pressure in a patient that has orthostatic hypotension, which is a fall in blood pressure on standing up. Many POTS patients do not tolerate caffeine because their sympathetic nervous system is already in overdrive, and caffeine will often aggravate their tachycardia.

*Information from article published by Dr. Phillip A Low, M.D

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