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Acute volume loading and exercise capacity in postural tachycardia syndrome.

ABSTRACT: Postural tachycardia syndrome (POTS) is associated with exercise intolerance, hypovolemia, and cardiac atrophy, which may contribute to reduced stroke volume and compensatory exaggerated heart rate (HR) increases. Acute volume loading with intravenous (iv) saline reduces HR and improves orthostatic tolerance and symptoms in POTS, but its effect on exercise capacity is unknown. In this study, we determined the effect of iv saline infusion on peak exercise capacity (VO2peak) in POTS. Nineteen patients with POTS participated in a sequential study. VO2peak was measured on two separate study days, following administration of placebo or 1 liter of i.v. saline (NaCl 0.9%). Patients exercised on a semirecumbent bicycle with resistance increased by 25 W every 2 min until maximal effort was achieved. Patients exhibited blood volume deficits (-13.4 ± 1.4% ideal volume), consistent with mild to moderate hypovolemia. At baseline, saline significantly increased stroke volume (saline 80 ± 8 ml vs. placebo 64 ± 4 ml; P = 0.010), increased cardiac output (saline 6.9 ± 0.5 liter/min vs. placebo 5.7 ± 0.2 liter/min; P = 0.021), and reduced systemic vascular resistance (saline 992.6 ± 70.0 dyn-s/cm(5) vs. placebo 1,184.0 ± 50.8 dyn-s/cm(5); P = 0.011), with no effect on HR or blood pressure. During exercise, saline did not produce differences in VO2peak (saline 26.3 ± 1.2 mg·kg(-1)·min(-1) vs. placebo 27.7 ± 1.8 mg·kg(-1)·min(-1); P = 0.615), peak HR [saline 174 ± 4 beats per minute (bpm) vs. placebo 175 ± 3 bpm; P = 0.672] or other cardiovascular parameters. These findings suggest that acute volume loading with saline does not improve VO2peak or cardiovascular responses to exercise in POTS, despite improvements in resting hemodynamic function.

SUBMITTER: Figueroa RA

PROVIDER: S-EPMC4157162 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Acute volume loading and exercise capacity in postural tachycardia syndrome.

Figueroa Rocío A RA Arnold Amy C AC Nwazue Victor C VC Okamoto Luis E LE Paranjape Sachin Y SY Black Bonnie K BK Diedrich Andre A Robertson David D Biaggioni Italo I Raj Satish R SR Gamboa Alfredo A

Journal of applied physiology (Bethesda, Md. : 1985) 20140724 6

Postural tachycardia syndrome (POTS) is associated with exercise intolerance, hypovolemia, and cardiac atrophy, which may contribute to reduced stroke volume and compensatory exaggerated heart rate (HR) increases. Acute volume loading with intravenous (iv) saline reduces HR and improves orthostatic tolerance and symptoms in POTS, but its effect on exercise capacity is unknown. In this study, we determined the effect of iv saline infusion on peak exercise capacity (VO2peak) in POTS. Nineteen pati ...[more]

PMID: 25059240

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Project description:Background and purposePostural orthostatic tachycardia syndrome (POTS) is increasingly recognized as a complication affecting recovery from concussion. Individuals with POTS demonstrate refractory dizziness, lightheadedness, cognitive dysfunction, fatigue, headache, chronic pain, nausea and gastrointestinal dysmotility, activity and exercise intolerance, syncope, and tachycardia. Subtypes of POTS may include hypovolemia, hyperadrenergic states, autonomic neuropathy, and underlying autoimmunity, which may variably impact response to rehabilitation in varying ways. The subtle presentation of POTS postconcussion is often mistaken for underlying anxiety, conversion disorder, or lack of motivation for recovery. This article will present clinical features of POTS that may arise after concussion, and propose a role for physical therapists in the diagnosis and management of POTS during concussion recovery.Summary of key pointsData recorded and entered into a database during clinic visits from a large pediatric institution indicate that 11.4% of individuals diagnosed with POTS report onset of symptoms within 3 months of sustaining a concussion. Activation of the sympathetic nervous system can result in lightheadedness, shortness of breath, chest pain, tachycardia, palpitations on standing or with exertion, and activity and exercise intolerance. Identified comorbidities in people with POTS such as joint hypermobility and autoimmune disorders can further influence recovery.Recommendations for clinical practicePhysical therapists may identify signs and symptoms of POTS in a subset of individuals who remain refractory to typical interventions and who exhibit symptom exacerbation with orthostatic activity. Incorporation of an individualized POTS exercise program into current established concussion interventions may be useful, with emphasis on initial recumbent exercises and ongoing physical therapy assessment of exercise tolerance for dosing of activity intensity and duration.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A211).

Project description:Background:Postural tachycardia syndrome (POTS) is a complex syndrome of orthostatic intolerance that significantly affects quality of life. The relationship between functional capacity, quality of life, and age remains poorly understood in this patient population. The purpose of this cross-sectional study was to assess the clinical and exercise characteristics of patients with POTS who underwent exercise stress testing as part of cardiac rehabilitation, and to evaluate the relationships between functional capacity with age and sex, as well as the relationship between functional capacity and quality of life. Methods:We included 255 consecutive adult patients with the diagnosis of POTS, by tilt table testing, who underwent exercise stress testing between 2012 and 2017. Clinical and stress test data were obtained from electronic medical records. Results:Of the 255 patients, 232 (91%) were women, with median age 33.5 years. Prevalence of traditional CAD risk factors was low (2% diabetes, 13% hypertension, 7% hyperlipidemia, and 26% smoking history). Mean resting BP was 114 ± 13 mmHg systolic, resting HR was 76 ± 13 bpm, METs achieved 9.2 ± 2.2, and 1 min HR recovery 32 ± 17 bpm. 113 patients (44%) had abnormal functional capacity for age and sex. When analyzed by age groups, younger POTS patients had increasingly lower than expected functional capacity (compared to predicted normals) than did older patients (ANOVA P = 0.0017). The SF-36 physical component of patients with abnormal functional capacity was significantly lower than those with normal functional capacity. (p = 0.006). Conclusions:In this large cohort, patients with POTS were predominantly female (91%) and relatively young. The novel findings are that younger patients with POTS were more likely to have lower-than-average functional capacity for their age and sex compared to older patients, and that abnormal functional capacity was associated with lower quality of life by SF-36 physical component.

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Acute volume loading and exercise capacity in postural tachycardia syndrome.

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Acute volume loading and exercise capacity in postural tachycardia syndrome.

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