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Diurnal variability in orthostatic tachycardia: Implications for Postural Tachycardia Syndrome – Source: Clinical Science, Jul 14, 2011

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[Note: POTS is a dysregulation of ‘automatic’ heart rate/blood pressure adjustments that support changes in the body’s requirements – e.g., in POTS heart rate is exaggerated (tachycardia) on rising from prone to upright position. ME/CFS and POTS are often associated and “may share a common pathophysiology.”]

Patients with Postural Tachycardia Syndrome (POTS) have excessive orthostatic tachycardia (<30 bpm) when standing from a supine position [lying on the back].

Heart rate (HR) and blood pressure (BP) are known to exhibit diurnal variability [variation depending on time of day], but the role of diurnal variability in orthostatic changes of HR & BP is not known.

In this study, we tested the hypothesis that there is diurnal variation of orthostatic HR & BP in patients with POTS and healthy controls. Patients with POTS (n=54) and healthy volunteers (n=26) were admitted to the Clinical Research Center.

Supine and standing (5 min) HR & BP were obtained on the evening on the day of admission and in the following morning. Overall, standing HR was significantly higher in the morning than the evening (102±3 bpm [AM] vs. 93±2 bpm [PM]; P<0.001).

Standing HR was higher in the morning in both POTS patients (108±4 bpm [AM] vs. 100±3 bpm [PM]; P=0.012) and controls (89±3 bpm [AM] vs. 80±2 bpm [PM]; P=0.005), when analyzed separately.

There was no diurnal variability in orthostatic BP in POTS.

More subjects met the POTS HR criterion in the morning compared with the evening (P=0.008).[bolding added]

There was significant diurnal variability in orthostatic tachycardia, with a great orthostatic tachycardia in the morning compared to the evening in both patients with POTS and healthy subjects.

Given the importance of orthostatic tachycardia in diagnosing POTS, this diurnal variability should be considered in the clinic as it may affect the diagnosis of POTS.

Source: Clinical Science, Jul 14, 2011. Brewster JA, Garland EM, Biaggioni I, Black BK, Ling JF, Shibao CA, Robertson D, Raj SR.Vanderbilt University School of Medicine, Nashville, Tennessee, USA. [Email: satish.raj@venderbilt.edu]

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2 thoughts on “Diurnal variability in orthostatic tachycardia: Implications for Postural Tachycardia Syndrome – Source: Clinical Science, Jul 14, 2011”

  1. happydancer says:

    Interesting article. Maybe I’m not getting a real clear picture of the study but I would have guessed that a person would have orthostatic variability in the morning. My hypotheses would be that no fluids during the night, early a.m. urination, result would be a fluid volume issue. I have recently been giving my geriatric mother fluids in the morning before she really gets out of bed to avoid any kind of orthostatic problem. Naturally, I thought my success was volume, but now I wonder if some of it could be due to the minerals and purest colloids I have been adding to the water or juice. Just when I think I have things figured out, I discover there is so much more to learn.

  2. toddm1960 says:

    It would be nice if research documents could get it straight, POTS HAS NOTHING TO DO WITH BLOOD PRESSURE. A drop in BP would be NCS or NMS, you can have both. Just do not include hypotension as a criteria for POTS. Since they can’t take the time to get the symptoms correct, I’m not sure if you can trust anything in this paper.

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