Patients with POTS exhibited higher resting venous pressure (16 vs. 10 mmHg) and a lower threshold for edema formation (8.3 vs. 16.3 mmHg) compared with normal controls.
Case-Control (n=23)
How do arterial and venous vascular properties differ between adolescent POTS patients and normal controls during supine and head-up tilt positions?
Adolescent POTS patients exhibit higher resting venous pressure and a lower threshold for edema formation, predisposing them to lower extremity fluid pooling and potentially contributing to tachycardia via vagal withdrawal.
Absolute Event Rate: 16% vs 10%
Chronic orthostatic intolerance is often related to the postural orthostatic tachycardia syndrome (POTS). POTS is characterized by upright tachycardia. Understanding of its pathophysiology remains incomplete, but edema and acrocyanosis of the lower extremities occur frequently. To determine how arterial and venous vascular properties account for these findings, we compared 13 patients aged 13-18 yr with 10 normal controls. Heart rate and blood pressure were continuously recorded, and strain-gauge plethysmography was used to measure forearm and calf blood flow, venous compliance, and microvascular filtration while the subject was supine and to measure calf blood flow and calf size change during head-up tilt. Resting venous pressure was higher in POTS compared with control (16 vs. 10 mmHg), which gave the appearance of decreased compliance in these patients. The threshold for edema formation decreased in POTS patients compared with controls (8.3 vs. 16.3 mmHg). With tilt, early calf blood flow increased in POTS patients (from 3.4 +/- 0.9 to 12.6 +/- 2.3 ml. 100 ml(-1). min(-1)) but did not increase in controls. Calf volume increased twice as much in POTS patients compared with controls over a shorter time of orthostasis. The data suggest that resting venous pressure is higher and the threshold for edema is lower in POTS patients compared with controls. Such findings make the POTS patients particularly vulnerable for edema fluid collection. This may signify a redistribution of blood to the lower extremities even while supine, accounting for tachycardia through vagal withdrawal.
Stewart et al. (2000) conducted a case-control in Postural orthostatic tachycardia syndrome (POTS) (n=23). Postural orthostatic tachycardia syndrome (POTS) vs. Normal controls was evaluated on Resting venous pressure (mmHg). Patients with POTS exhibited higher resting venous pressure (16 vs. 10 mmHg) and a lower threshold for edema formation (8.3 vs. 16.3 mmHg) compared with normal controls.