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Splanchnic-mesenteric capacitance bed in the postural tachycardia syndrome (POTS)
1Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
Autonomic Neuroscience : Basic & Clinical
|March 29, 2001
Summary
Patients with postural tachycardia syndrome (POTS) exhibit excessive splanchnic blood pooling at rest. This finding helps explain common gastrointestinal issues in POTS patients.
Area of Science:
- Cardiovascular Physiology
- Gastroenterology
- Autonomic Dysfunction
Background:
- Gastroenterologic symptoms are prevalent in Postural Tachycardia Syndrome (POTS).
- Orthostatic symptom exacerbation after meals is common in POTS.
- Splanchnic-mesenteric vasoregulation in POTS requires further investigation.
Purpose of the Study:
- To investigate splanchnic-mesenteric vasoregulation in patients with POTS.
- To compare hemodynamic responses to orthostatic stress and a meal in POTS patients and healthy controls.
Main Methods:
- Eleven POTS patients and 10 controls underwent head-up tilt (HUT) and hyperventilation tests, before and after a liquid meal.
- Continuous monitoring of blood pressure, heart rate, end-tidal CO2, and cardiovascular indices.
- Superior mesenteric artery (SMA) blood flow, area, velocity, and vascular resistance were measured using Doppler ultrasound.
Main Results:
- POTS patients exhibited higher resting heart rate, blood pressure, SMA blood flow, and SMA velocity, with lower SMA vascular resistance compared to controls.
- Both groups showed reduced pulse pressure, CO2, SMA area, SMA velocity, and increased heart rate and SMA vascular resistance during HUT.
- POTS patients had a greater heart rate increase and CO2 reduction during HUT.
- Hyperventilation increased heart rate and cardiac index, and reduced SMA vascular resistance in controls, but not in POTS patients.
- A test meal increased heart rate, cardiac index, SMA area, SMA velocity, and decreased SMA vascular resistance in both groups.
Conclusions:
- Increased resting superior mesenteric artery blood flow and velocity, along with reduced vascular resistance, suggest excessive splanchnic pooling at rest in POTS.
- These findings support the hypothesis of abnormal splanchnic vascular regulation contributing to POTS symptoms.
- Understanding splanchnic vasoregulation is crucial for managing gastrointestinal dysfunction in POTS.
Keywords:
Non-programmatic