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Altered systemic hemodynamic and baroreflex response to angiotensin II in postural tachycardia syndrome.

ABSTRACT: Postural tachycardia syndrome (POTS) is characterized by excessive orthostatic tachycardia and significant functional disability. We have previously found that patients with POTS have increases in plasma angiotensin II (Ang II) that are twice as high as healthy subjects despite normal blood pressures (BPs). In this study, we assess systemic and renal hemodynamic and functional responses to Ang II infusion in patients with POTS compared with healthy controls.Following a 3-day sodium-controlled diet, we infused Ang II (3 ng/kg per minute) for 1 hour in patients with POTS (n=15) and healthy controls (n=13) in the supine position. All study subjects were women with normal BP. Ages were similar for patients with POTS and controls (mean±SEM, 30±2 versus 26±1 years; P=0.11). We measured the changes from baseline mean arterial pressure, renal plasma flow, plasma renin activity, aldosterone, urine sodium, and baroreflex sensitivity in both groups. In response to Ang II infusion, patients with POTS had a blunted increase compared with controls in mean arterial pressure (10±1 versus 14±1 mm Hg, P=0.01) and diastolic BP (9±1 versus 13±1 mm Hg, P=0.01) but not systolic BP (13±2 versus 15±2 mm Hg, P=0.40). Renal plasma flow decreased similarly with Ang II infusion in patients with POTS versus controls (-166±20 versus -181±17 mL/min per 1.73 kg/m(2), P=0.58). Postinfusion, the decrease in plasma renin activity (-0.9±0.2 versus -0.6±0.2 ng/mL per hour, P=0.43) and the increase in aldosterone (17±1 versus 15±2 pg/mL, P=0.34) were similar in both groups. The decrease in urine sodium excretion was similar in patients with POTS and controls (-49±12 versus -60±16 mEq/g creatinine, P=0.55). The spontaneous baroreflex sensitivity at baseline was significantly lower in patients with POTS compared with controls (10.1±1.2 versus 16.8±1.5 ms/mm Hg, P=0.003), and it was further reduced with Ang II infusion.Patients with POTS have blunted vasopressor response to Ang II and impaired baroreflex function. This impaired vasoconstrictive response might be exaggerated with upright posture and may contribute to the subsequent orthostatic tachycardia that is the hallmark of this disorder. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00962949.

SUBMITTER: Mustafa HI

PROVIDER: S-EPMC3577936 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Altered systemic hemodynamic and baroreflex response to angiotensin II in postural tachycardia syndrome.

Mustafa Hossam I HI Raj Satish R SR Diedrich André A Black Bonnie K BK Paranjape Sachin Y SY Dupont William D WD Williams Gordon H GH Biaggioni Italo I Robertson David D

Circulation. Arrhythmia and electrophysiology 20120113 1

<h4>Background</h4>Postural tachycardia syndrome (POTS) is characterized by excessive orthostatic tachycardia and significant functional disability. We have previously found that patients with POTS have increases in plasma angiotensin II (Ang II) that are twice as high as healthy subjects despite normal blood pressures (BPs). In this study, we assess systemic and renal hemodynamic and functional responses to Ang II infusion in patients with POTS compared with healthy controls.<h4>Methods and res ...[more]

PMID: 22247480

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Project description:Gastrointestinal (GI) symptoms are common in postural orthostatic tachycardia syndrome (POTS). We aimed to explore the prevalence and severity of GI symptoms in POTS, and to investigate immunological factors, hemodynamic findings, and their possible association with GI symptoms in POTS. Forty-three patients (93% female, median age 30.6 (26.0-41.0) years), previously diagnosed with POTS and 74 healthy controls (78% female, median age 35.6 (28.8-41.7) years) were included. The participants completed a questionnaire including prevalence of GI symptoms, the irritable bowel syndrome severity scoring system (IBS-SSS), and visual analog scale for IBS (VAS-IBS). All POTS patients were previously examined by tilt test (2010-2021) and the vast majority with more recent active standing test (2017-2021), which included monitoring of heart rate (HR). ΔHR was calculated as difference between supine and upright position. Continuous variables from IBS-SSS and VAS-IBS were correlated to ΔHR. A microarray containing several autoantigens commonly targeted in systemic autoimmune disorders was used to assess prevalent autoantibodies in POTS and controls. Total IgE and S-tryptase were analyzed. GI symptoms were more prevalent and severe in POTS than in controls; nausea being the most prevalent (79.1% vs 4.9%, p < 0.001) and bloating and flatulence being the most severe (median 65 (25-88) vs 0 (0-14), p < 0.001). The median total IBS-SSS was 213 (135-319) in POTS vs 13 (0-54) in controls (p < 0.001). Total IBS-SSS was associated with low psychological wellbeing (r = 0.539, p < 0.001) in POTS. ΔHRmax correlated inversely with abdominal pain (r = -0.406, p = 0.007). After adjustments for psychological wellbeing, total IBS-SSS still associated inversely with ΔHR10min (β: 4.748; 95% CI: -9.172 to -0.324; p = 0.036). Similar results were seen with active standing test. The prevalence of autoantibodies did not differ between POTS and controls (29.4% vs 33.3%, p = 0.803). There was no association between GI symptoms and autoantibody status. Total IgE and tryptase were elevated in a few cases. This study confirms the high prevalence of GI symptoms in POTS. More pronounced tachycardia upon tilt table testing seems to be inversely correlated with severity of chronic GI symptoms in POTS. This study did not support the hypothesis that POTS is associated with immunological factors.

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Altered systemic hemodynamic and baroreflex response to angiotensin II in postural tachycardia syndrome.

Publications

Altered systemic hemodynamic and baroreflex response to angiotensin II in postural tachycardia syndrome.

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