TY - JOUR
T1 - Hemodynamics of orthostatic intolerance
T2 - Implications for gender differences
AU - Fu, Qi
AU - Arbab-Zadeh, Armin
AU - Perhonen, Merja A.
AU - Zhang, Rong
AU - Zuckerman, Julie H.
AU - Levine, Benjamin D
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2004/1
Y1 - 2004/1
N2 - Women have a greater incidence of orthostatic intolerance than men. We hypothesized that this difference is related to hemodynamic effects on regulation of cardiac filling rather than to reduced responsiveness of vascular resistance during orthostatic stress. We constructed Frank-Starling curves from pulmonary capillary wedge pressure (PCWP), stroke volume (SV), and stroke index (SI) during lower body negative pressure (LBNP) and saline infusion in 10 healthy young women and 13 men. Orthostatic tolerance was determined by progressive LBNP to presyncope. LBNP tolerance was significantly lower in women than in men (626.8 ± 55.0 vs. 927.7 ± 53.0 mmHg ± min, P < 0.01). Women had steeper maximal slopes of Starling curves than men whether expressed as SV (12.5 ± 2.0 vs. 7.1 1.5 ml/mmHg, P ± 0.05) or normalized as SI (6.31 ± 0.8 vs. 4.29 ± 0.6 mI·m -2·mmHg-1, P < 0.05). During progressive LBNP, PCWP dropped quickly at low levels, and reached a plateau at high levels of LBNP near presyncope in all subjects. SV was 35% and SI was 29% lower in women at presyncope (both P < 0.05). Coincident with the smaller SV, women had higher heart rates but similar mean arterial pressures compared with men at presyncope. Vascular resistance and plasma norepinephrine concentration were similar between genders. We conclude that lower orthostatic tolerance in women is associated with decreased cardiac filling rather than reduced responsiveness of vascular resistance during orthostatic challenges. Thus cardiac mechanics and Frank-Starling relationship may be important mechanisms underlying the gender difference in orthostatic tolerance.
AB - Women have a greater incidence of orthostatic intolerance than men. We hypothesized that this difference is related to hemodynamic effects on regulation of cardiac filling rather than to reduced responsiveness of vascular resistance during orthostatic stress. We constructed Frank-Starling curves from pulmonary capillary wedge pressure (PCWP), stroke volume (SV), and stroke index (SI) during lower body negative pressure (LBNP) and saline infusion in 10 healthy young women and 13 men. Orthostatic tolerance was determined by progressive LBNP to presyncope. LBNP tolerance was significantly lower in women than in men (626.8 ± 55.0 vs. 927.7 ± 53.0 mmHg ± min, P < 0.01). Women had steeper maximal slopes of Starling curves than men whether expressed as SV (12.5 ± 2.0 vs. 7.1 1.5 ml/mmHg, P ± 0.05) or normalized as SI (6.31 ± 0.8 vs. 4.29 ± 0.6 mI·m -2·mmHg-1, P < 0.05). During progressive LBNP, PCWP dropped quickly at low levels, and reached a plateau at high levels of LBNP near presyncope in all subjects. SV was 35% and SI was 29% lower in women at presyncope (both P < 0.05). Coincident with the smaller SV, women had higher heart rates but similar mean arterial pressures compared with men at presyncope. Vascular resistance and plasma norepinephrine concentration were similar between genders. We conclude that lower orthostatic tolerance in women is associated with decreased cardiac filling rather than reduced responsiveness of vascular resistance during orthostatic challenges. Thus cardiac mechanics and Frank-Starling relationship may be important mechanisms underlying the gender difference in orthostatic tolerance.
KW - Lower body negative pressure
KW - Orthostatic hypotension
KW - Pulmonary capillary wedge pressure
KW - Stroke volume
KW - Vascular resistance
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U2 - 10.1152/ajpheart.00735.2002
DO - 10.1152/ajpheart.00735.2002
M3 - Article
C2 - 14527942
AN - SCOPUS:0345737069
VL - 286
SP - H449-H457
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
SN - 0363-6135
IS - 1 55-1
ER -