Why the study?
In postural tachycardia syndrome (POTS), hemodynamic changes due to postural changes are poorly understood, and whether inappropriate upright venous return can be detected by echocardiography was unknown.
Does postural change from supine to sitting reveal differences in stroke volume and venous return in school children with POTS compared to healthy controls?
Does postural change from supine to sitting reveal differences in stroke volume and venous return in school children with POTS compared to healthy controls?
Echocardiographic assessment during postural change from supine to sitting reveals decreased stroke volume and venous return in school children with POTS, highlighting underlying hemodynamic pathophysiology.
Echocardiography may identify reduced venous return in pediatric POTS; hypothesis-generating for hemodynamic subtyping and requires prospective validation before clinical use.
In postural tachycardia syndrome (POTS), a subtype of orthostatic intolerance, the changes in hemodynamics due to postural changes are poorly understood. We speculated that inappropriate venous return, which may occur in the upright position in patients with school-aged POTS, could be detected by echocardiography. Our prospective study was conducted with 100 POTS patients (45 boys and 55 girls), aged 13.1 ± 1.5 years and 52 age- and sex-matched healthy subjects (control). Echocardiography was performed in the supine and sitting positions. Cardiac parameters [stroke volume index, cardiac index, heart rate, and the maximum inferior vena cava diameter (max IVC)] were evaluated in addition to pulse pressure. Unlike the control subjects, POTS patients demonstrated decreased stroke volume index (P = 0.02) and max IVC (P < 0.01) irrespective of posture. The rates of max IVC change did not differ between control and POTS groups. The enrolled POTS patients were divided into two subgroups [dilatation (n = 57) and contraction (n = 43)] based on whether the change rate of max IVC was less than zero or not. The contraction group showed a significantly higher heart rate than the dilatation group with respect to posture (P = 0.03), indicating the poor response of peripheral vessels in the lower limbs only in the contraction group. In conclusion, echocardiographic assessment detected decreased stroke volume and venous return in POTS. The changes in max IVC in response to postural changes may indicate an underlying pathophysiology in POTS.
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Jimbo et al. (2021) studied this question.
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