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Studying Splanchnic Venous Capacitance in POTS

This study is investigating Postural Tachycardia Syndrome (POTS), a condition causing dizziness and lightheadedness when standing, especially after meals. Researchers want to understand if the worsening of POTS symptoms after eating sugary foods is linked to increased blood pooling in the splanchnic circulation (blood vessels in your abdomen). They will measure how much blood pools in these vessels using a special technique involving continuous positive airway pressure (CPAP). Some participants with POTS will receive either saline or GIP(3-30)NH2, a drug that blocks a hormone called GIP, to see if it changes blood flow. You may be eligible if you are 18-50 years old with a POTS diagnosis and post-meal symptoms, or a healthy control. The study aims to understand how glucose affects blood pooling and POTS symptoms. The current status of the study is unclear.

Study design
This interventional study plans to enroll 50 participants, including those with POTS and healthy controls. Participants with POTS will be randomly assigned to receive either saline or GIP(3-30)NH2.
What's involved
Participants will undergo measurements of splanchnic venous capacitance and superior mesenteric arterial flow at baseline and after a 75-gram glucose drink, both lying down and tilted upright. These measurements will occur for up to 3 hours.
Compensation
Not stated in the trial record.
Follow-up
Measurements will be taken up to 180 minutes after a glucose challenge to observe changes in splanchnic venous capacitance and symptoms.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT05375968

Splanchnic Venous Capacitance in Postural Tachycardia Syndrome

Recruiting
PHASE2Ages 18–50InterventionalDiagnostic
Vanderbilt University Medical Center
~50 participants
Updated 2025-12-05 on ClinicalTrials.gov
What's tested:Measurement of Splanchnic venous capacitance(SVC)done at Baseline and after 90 min of 75 g glucose in Healthy Controls POTS patientsMeasurement of Splanchnic venous capacitance(SVC)done at Baseline and after 90 min of 75 g glucose in Healthy ControlsCompare change is SVC and SMA flow due to GIP antagonist GIP(3-30)NH2Compare change is SVC and SMA flow due to saline

At a glance

Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Change in splanchnic venous capacitance in Postural Orthostatic Tachycardia Syndrome
Measured over Baseline up to 180 minutes post glucose challenge
+2 more outcomes measured

Conditions

Postural Tachycardia Syndrome (POTS)

Explore related trials

Postural Orthostatic Tachycardia Syndrome

NCT05375968

Where you'd take part

This study runs at 1 site. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

  • Vanderbilt University Medical Center

    Nashville, Tennesseestudy coordinator listed

    Recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

Study leadership

  • Cyndya Shibao, M.D · PRINCIPAL_INVESTIGATOR · Vanderbilt University Medical Center

Who to contact

Pedro J Ortiz, MD
[email protected]
689-233-2623
Email the study team

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Eligibility criteria

Inclusion

Between 18 and 50years of age
Cases: Diagnosis of POTS with presyncope symptoms after meals Or
With no significant past medical history, non-smokers and not on chronic medications.
Body mass index (BMI) between 18.5 to 29.9 kg/m2
If pre-menopausal women: must have regular menstrual cycle.

Exclusion

BMI above ≥30 kg/m2
Irregular menstrual cycle
Intolerance to CPAP.
Chronic use of acetaminophen
Heart problems: myocardial infarction, angina, heart failure, stroke
Undergone any heart related procedures or stents or on pacemaker.
Uncontrolled hypertension.
Type 1 or type 2 diabetes mellitus
Pregnant or breast-feeding women.
Impaired liver function
Impaired Kidney function test.
Anemia (Hematocrit\<34%).
Ongoing substance abuse.
Subjects with abnormal EKG
History of seizures.
Diagnosed with neuropathy due to any reason
History of neck surgery.
Smoker,
On statin therapy for high cholesterol
Rheumatoid arthritis.
On oral corticosteroids,
Current infections
Documented of moderate decrease in blood volume

What this trial measures

  • Change in splanchnic venous capacitance in Postural Orthostatic Tachycardia SyndromeBaseline up to 180 minutes post glucose challenge

    The changes in splanchnic venous capacitance and superior mesenteric arterial flow will be measured, before and after a 75 gram of oral glucose challenge. It will compared in POTS and Healthy controls. While segmental bio impedance is monitored, continuous positive airway pressure (CPAP) will be applied sequentially at 0, 4, 8, 12 and 16 cm H2O for about 30 seconds each; this positive airway pressure will increase the intrathoracic pressure, which is transmitted to the venous circulation. Pressure (CPAP pressure, x-axis) - volume (splanchnic vascular volume measured by segmental impedance and expressed as % change from baseline, y-axis) relationships are then constructed to assess for splanchnic venous capacitance.

  • Effect of glucose-induced GIP secretion on splanchnic venous capacitance0-180 mins

    25 participants with POTS diagnosis, will be randomized them to either saline versus GIP antagonist (GIP(3-30)NH2) acute infusion. We will measure changes in their splanchnic venous capacitance and superior mesenteric arterial flow before and after a 75-g oral glucose challenge during supine and 45-degree head-up tilt positions (orthostatic challenge) for up to 3 hr

  • Effect of glucose-induced GIP secretion on POTS postprandial symptoms.0-90 mins

    Compare the post prandial symptoms on the participants who got infused with GIP antagonist GIP(3-30)NH2 and compare it with Saline infused participants at baseline and 45 degree head tilt. Total of 25 participants with diagnosis of POTS will randomized at visit 2, as 1:1 saline vs GIP antagonist GIP(3-30)NH2 At visit 3, the subjects who received Saline, will get GIP antagonist GIP(3-30)NH2 , vice versa.