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Updated: Jul 6, 2026

Non-invasive Assessment of Microvascular and Endothelial Function
Published on: January 29, 2013
Arterial hemodynamics in human hypertension
Insights
Hypertension is linked to higher aortic impedance, including increased resistance and reflections. Vasodilatation normalized these differences, suggesting increased vasomotor tone contributes to hypertension.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Hemodynamics
Background:
- Aortic impedance differences between normotensive and hypertensive individuals are not well understood.
- Essential hypertension is characterized by complex hemodynamic alterations.
Purpose of the Study:
- To investigate and characterize aortic impedance parameters in hypertensive versus normotensive patients.
- To explore the impact of vasodilatation and beta-blockade on these hemodynamic differences.
Main Methods:
- Cardiac catheterization was performed on 8 normotensive and 11 hypertensive Chinese patients.
- Measurements were taken at rest, during nitroprusside administration, and handgrip exercise, before and after propranolol (beta blockade).
Main Results:
- Hypertensives exhibited significantly higher resistance, characteristic impedance, total external power, peripheral reflections, and first zero crossing of impedance phase angle.
- Vasodilatation with nitroprusside normalized these abnormal impedance parameters.
- Beta blockade (propranolol) increased resistance and reflections in both groups.
Conclusions:
- Hemodynamic abnormalities in essential hypertension, including increased resistance and reflections, are associated with elevated vasomotor tone.
- This increased tone is further revealed by beta-blockade and can be reversed by vasodilatation.
Abstract:
Differences in aortic impedance between normotensives and hypertensives are not well characterized. We examined impedance in 8 normotensive and 11 hypertensive (mean 96.7 vs. 122.2 mmHg) age-matched, Chinese patients undergoing cardiac catheterization at rest, during nitroprusside, and handgrip exercise before and after beta blockade (propranolol). Hypertensives had higher resistance (2,295 vs. 1713 dyn-s/cm5), characteristic impedance (145.7 vs. 93.9 dyn-s/cm5), total external power (1,579 vs. 1174 mW), peripheral reflections (ratio of backward to forward wave components of 0.54 vs. 0.44), and first zero crossing of impedance phase angle (4.15 vs. 2.97 Hz). These abnormalities were eliminated with vasodilatation. Differences between groups were not further exacerbated when pressure was increased during handgrip exercise. Beta blockade further increased resistance and reflections. Thus, hemodynamic abnormalities of essential hypertension (increased resistance, reflections, and pulse wave velocity, and decreased compliance) are compatible with an increased vasomotor tone that is further unmasked during generalized beta blockade.
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