Postural Orthostatic Tachycardia Syndrome (POTS) is a clinical syndrome characterized by the presence of tachycardia in the absence of orthostatic hypotension; symptoms of orthostatic intolerance (presyncope and syncope) are present secondary to autonomic dysfunction (1). It is thought that one of the implications for POTS involves plasma volume disturbances leading to blood pooling. The Renin Angiotensin Aldosterone System (RAAS) is one system that assists in plasma volume regulation (2). In this study we hypothesized that these disturbances are brought about by an inactivation of RAAS. This was done by retrospectively reviewing the medical records of POTS patients. In these patients, diagnosis of POTS was established by an increase in Heart Rate of over 30 bpm within 10 minutes of tilt. Stroke Volume was used as a measure of volume disturbances; those POTS patients whose stroke volumes had not increased by the End of the Tilt as compared to their 6 minute supine baseline were considered to have an inactivation of RAAS. Our total sample of POTS patients numbered at 447, out of which 417 patients had lower stroke volumes at the end of their tilt table tests when compared to their baseline; this makes for 92.87% of our POTS Patient Sample. The average Stroke Volume at the 6 minute mark was calculated to be 74.67; the average stroke volume at the end of the tilt table test (30 minutes) was calculated to be 46.33 mL; . The results seen in this study show that more than 90% of our POTS Patient Sample there is no recovery of the stroke volume by the end of the tilt table test, this volume disturbance can be the result of decreased RAAS activation. This observation is supported by the difference found between average stroke volumes seen at 6 minute baseline and at 30 minutes of tilt. In normal individuals, we should see an increase in stroke volume at the end of the tilt as RAAS is activated. However, as patients with POTS are known to have lower plasma volumes (2), compounded with the inactivation of RAAS; the resulting hypovolemia will amplify the symptoms of POTS, increasing their severity. These patients should respond well to fludrocortisone, as there will be a correction of hemodynamic impairments (RAAS inactivation) leading to symptomatic relief (3). Further studies and analyses are needed to look into the levels of Renin and Aldosterone at Baseline & at Tilt, as well as the effects of fludrocortisone on such patients with RAAS inactivation. References:(1) Satish R. R., Circulation. 2013. June 11; 127(23): 2336-2342.(2) Satish R. R. et al., Circulation. 2005. March 2; 111(13): 1574-1582. (3) Freitas. J et al., Clin Auton Res. 2000. October; 10(5): 293-303. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to ...

Thoracic outlet syndrome (TOS) refers to a constellation of symptoms resulting from neurovascular compression at the thoracic outlet, causing some combination of pain in the neck and upper extremity, weakness, sensory loss, paresthesia, swelling, and discoloration. Classification of TOS would depend on the anatomical structure that is compressed: venous TOS (VTOS)—compression of Subclavian vein; arterial TOS (ATOS)—compression of subclavian artery; and neurogenic TOS (NTOS)—compression of brachial plexus. Postural Orthostatic Tachycardia Syndrome (POTS) is characterized by orthostatic tachycardia that develops in the absence of orthostatic hypotension, with a symptom duration of >6 months. POTS is now known to be commonly associated with Ehlers-Danlos Syndrome (EDS), thereby raising speculation about the extent of prevalence of TOS symptoms in EDS patients. The aim of the study was to quantify the influx of patients with POTS, reporting symptoms of arm fatigue with or without numbness and tingling. The symptoms were quantified initially by conducting postural maneuvers that would reproduce the symptoms, to rule-in the possibility of TOS and further confirmed by using ultrasonography in upper limbs as the imaging modality of choice to evaluate arterial and/or venous compression. This study also looks at the presence of a concurrent diagnosis of EDS among the symptomatic patients who test positive for TOS.

Introduction: Postural Orthostatic Tachycardia Syndrome (POTS) is a form of dysautonomia which primarily affects young adult women. The hallmark of this condition is an exaggerated heart rate in response to postural changes. The symptoms of POTS can cause cerebral hypoperfusion and include generalized weakness, dizziness, lightheadedness, darkening of the visual fields and in some, palpitations and loss of consciousness. Increased sympathetic activation results in increase of the conduction through the AV node. Increased conduction through the AV node results in a shorter PR interval and a faster heart rate. The aim of this study is to determine if patients with severe POTS have resting Adrenal Hyperactivity by utilizing PR-Intervals. Methods: A team of researchers randomly selected pts with POTS from our clinic. This group consisted of 455 pts and these pts’ tilt table results as well as their resting ECG’s were reviewed from their electronic medical records. Pts were then categorized based on the degree of change in heart rate during the tilt table test. The categories were as follows: Orthostatic intolerance (<30 bpm), mild POTS (30-50 bpm), and severe POTS (>50 bpm). A few patients in the data set did not have tilt table results and were subsequently removed. We noted the resting PR intervals of these pts from their multiple ECG’s. For each pt the mean of these values was gathered and biostatistical analysis was performed on this first collection of data. After the first data was analyzed, a second team of researchers, blinded to the first team, collected the same data set on patients with POTS from our clinic. This was done in order to minimize observer bias and reproduce results. This team of researchers further filtered out 8 patients whose data did not meet the criteria required to categorize the patients, thus the second data set consisted of 447 pts. Tilt table results and resting PR intervals were taken from their electronic medical records and the pts were then categorized in the same manner as the first data set. Results: In the second group of 447 pts (n=447), 28.6% (n= 128) are categorized as having orthostatic intolerance, 51.6% (n=231) are categorized as mild POTS, and 19.6% (n=88) are categorized as severe POTS. Using a significance level of 0.05, the P-value was lower than 0.05 (0.00787), thus ANOVA fails to accept the null hypothesis that the means of the PR-intervals across the various categories are equal. That is to say, statistically the resting PR intervals are not equal across the different POTS categories in both groups with a significance level of 0.05. Average P-R (Severe POTS:137.0 ms & Orthostatic Intolerance: 145.59 ms) Conclusion: A statistically significant increase in resting Adrenal Hyperactivity in pts with severe POTS (>50 bpm) as opposed to pts with Orthostatic Intolerance (<30 bpm); the severity of which may have long-term prognostic significanc...