Dietary Salt in Postural Tachycardia Syndrome
This trial is active, not recruiting.
|Condition||postural orthostatic tachycardia syndrome|
|Treatments||blood volume, total blood volume, exercise capacity test - bicycle, posture study|
|Collaborator||National Institutes of Health (NIH)|
|Start date||March 2012|
|End date||March 2017|
|Trial size||30 participants|
|Trial identifier||NCT01547117, 111261, R01HL102387|
Patients with POTS may not adequately expand their plasma volume in response to a high-sodium diet. Mechanisms involved in the regulation of plasma volume, such as the renin-angiotensin-aldosterone system and renal DA, may be impaired in POTS and may respond inappropriately to changes in dietary sodium.The purpose of this study is to determine (1) whether a high dietary sodium level appropriately expands plasma volume in POTS; (2) whether plasma renin activity and aldosterone are modified appropriately by changes in dietary sodium in POTS; and (3) whether patients with POTS have improvements in their orthostatic tachycardia and symptoms as a result of a high dietary sodium level.
|Intervention model||crossover assignment|
|Primary purpose||basic science|
time frame: after 7 days of each dietary sodium level
Magnitude of suppression of aldosterone (from low sodium to high sodium diets) and a reduction in orthostatic tachycardia and orthostatic symptoms in POTS patients with the high-sodium diet.
time frame: after 7 days of each dietary sodium intervention
Male or female participants from 18 years up to 50 years old.
- Diagnosed with postural tachycardia syndrome by the Vanderbilt Autonomic Dysfunction Center
- Increase in heart rate ≥30 beats/min with position change from supine to standing (10 minutes)
- Chronic symptoms consistent with POTS that are worse when upright and get better with recumbence
- Age between 18-50 years old
- Premenopausal patients with POTS and healthy volunteers
- Only female participants are eligible.
- Since 80-90% of POTS patients are female, and there can be differences in measures with the menstrual cycle, including a small number of males might introduce a significant amount of noise.
- Able and willing to provide informed consent
- Overt cause for postural tachycardia, i.e., acute dehydration
- Significant cardiovascular, pulmonary, hepatic, or hematological disease by history or screening results
- Pregnant (positive pregnancy test) or breastfeeding
- Hypertension defined as supine resting BP>145/95 mmHg off medications or needing antihypertensive medication
- Other factors which in the investigator's opinion would prevent the participant from completing the protocol, including poor compliance during previous studies or an unpredictable schedule
- Unable to give informed consent
|Official title||Dietary Salt in Postural Tachycardia Syndrome|
|Principal investigator||Satish R Raj, MD MSCI|
|Description||Study Day 1 - Start 150 mEq Na+/day diet (POTS patients as inpatients; healthy control subjects with CRC provided outpatient diet) - Start a 24h urine collection (for Na+, K+, Cr, fractionated catecholamines) - Blood work - Blood volume - carbon monoxide rebreathing Study Day 2 - Complete 24h urine - Start STUDY DIET (10 mEq Na+/day or 300 mEq Na+/day in a random order) after 3 meals of 150 mEq Na+/day are complete; water ad lib Study Day 3 - 5 - Continue STUDY DIET; water ad lib - On Day 5, a 24 hr holter combined ECG monitor will be placed on the subjects. Study Day 6 - Continue STUDY DIET; water ad lib - Remove 24h Holter combined ECG monitor and BP monitor from subject - Start a 24h urine collection (for Na+, K+, Cr, fractionated catecholamines) - Complete questionnaires - NPO after midnight for study next day Study Day 7 (BIG DAY) - Awaken early (~6am) to void (still collecting 24h urine) - Patient returns to bed, IV catheter inserted - Posture Study (in morning; between 7-8am ideally) - Blood pressure and heart rate will be measured while supine and then while standing for up to 30 minutes - We will draw 3 tablespoons of blood in each body position to measure hormones that regulate blood pressure and blood volume - Hormones to verify the subject's phase of menstrual cycle - Serum/plasma aliquots for future analysis - Subjects will rate symptoms during supine period and at end of stand using Vanderbilt Orthostatic Symptoms Score (VOSS) - Total Blood Volume (DAXOR)- using injection of iodinated I-131 tagged human serum albumin nominally 25 micro-Ci of radiation blood samples drawn through IV catheter before injection and for ~30 minutes post-injection (total - 25 ml) - This will be done after supine assessment, but before standing the subject up - Autonomic Function Test with Cardiac Output and Brief Tilt - The subject will be tilted up to 60-75 degrees head-up tilt for up to 10 minutes to measure the changes in heart rate and blood pressure and symptoms with upright challenge. - Blood volume - carbon monoxide rebreathing - Exercise Capacity Test (in the afternoon) Will estimate maximal oxygen consumption (VO2 max) This test will be conducted on a stationary bicycle. Effort will be gradually increase while expired air is measured during exhaustive physical work. All procedures are repeated at least a month later with the 2nd level of dietary salt. (Randomized to high or low salt to the first phase, the second phase is the remaining level)|
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