Table 1.

Patient dimensions and hemodynamic data

	Control	POTS
Weight, kg	72±5	69±4
Height, cm	167±4	167±3
Body surface area, m2	1.76±0.09	1.70±0.05
Normalized blood volume, ml/kg	65±5	68±6
Cardiac index (by ICG), l· min−1·m−2	3.5±0.5	4.3±0.6
Total peripheral resistance, mmHg·l−1·min·m2	31±4	23±5
Venous occlusion calf blood flow, ml·100 ml−1·min−1	2.3±0.4	2.7±0.3
HR phase 0, beats/min	63±5	81±3*
Systolic BP phase 0, mmHg	118±5	120±3
MAP phase 0, mmHg	82±4	89±4
Impedance blood flows phase 0, ml/min
Thoracic	5,805±824	4,975±720
Splanchnic	1,245±220	2,247±366*
Pelvic	662±171	618±127
Leg	112±18	93±14
% Change in blood volume during Valsalva maneuver
Thoracic	−9±1	−29±8*
Splanchnic	6±1	20±8*
Pelvic	2±1	1±1
Leg	1±1	1±1

Values are means ± SE. POTS, postural tachycardia syndrome; ICG, indocyanine green; HR, heart rate; BP, blood pressure; MAP, mean arterial pressure.

^*P < 0.05 difference compared with control subjects.