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[Properties of arteries, cardiac function and structure in chronic hypertension]
C Paillole1, J F Lerallut, J P Mérillon
1Service de cardiologie, hôpital Bichat, Paris.
Insights
Hypertension involves complex interactions between the left ventricle and the arterial system. Key factors include arterial stiffness, blood flow inertia, and wave reflections influencing aortic pressure.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Hypertension Research
Context:
- Hypertension links left ventricular (LV) properties with arterial system dynamics.
- Aortic impedance, a measure of resistance to blood flow, is influenced by arterial wall viscoelasticity, blood inertia, and wave reflections.
- Understanding these interactions is crucial for managing hypertensive conditions.
Purpose:
- To elucidate the relationship between left ventricular function and arterial system properties in hypertension.
- To analyze the factors contributing to altered aortic pressure waveforms in hypertensive individuals.
- To investigate the interplay of systemic arterial resistance, elastic forces, inertial forces, and pulse wave reflections.
Summary:
- Hypertension is characterized by increased mean aortic pressure (MAP), systolic, late systolic, and differential pressures, with a normal stroke volume.
- These changes result from increased systemic arterial resistance, heightened elastic forces due to arterial rigidity, and premature return of reflected pulse waves.
- A strong correlation exists between left ventricular mass, geometry (concentric hypertrophy), pump function, and arterial properties like pulse wave velocity and characteristic impedance.
Impact:
- Provides a deeper understanding of the biomechanical factors underlying hypertension.
- Highlights the significance of arterial properties (e.g., pulse wave velocity) in assessing cardiovascular risk.
- Suggests that interventions targeting arterial stiffness may be beneficial in managing hypertension.
Abstract:
Hypertension is a condition which demonstrates the relationship between the properties of the left ventricle and arterial system. The spectrum of aortic impedence expresses the principal factors which oppose LV ejection into the initial aorta: 1) capacitive forces related to the viscoelastic properties of the arterial wall, directly proportional to its rigidity, 2) forces of inertia which increase with the acceleration of the blood and which are inversely proportional to the aortic cross sectional area, 3) reflection. With respect to a stroke volume which is usually normal, hypertension is characterised by: 1) an increase in mean aortic pressure (MAP), 2) with respect to the increase in MAP, an increase in systolic, late systolic and differential pressures. These changes in the level and morphology of aortic pressure are due to: a) the increase in systemic arterial resistances, a continuous expression of the spectrum of the module, b) an increase in the elastic forces (increased rigidity of the aorta related to increased pressure and structural wall changes) usually insufficiently compensated by a decrease in the inertial forces (aortic dilatation), c) an earlier return of the reflected pulse wave, well before the end of the anterograde wave. Overall, there is a relationship between the mass, the geometry (concentric hypertrophy) and pump function of the left ventricle and the properties of the arterial system expressed in terms of pulse wave velocity, characteristic impedence or the late systolic pressure/stroke volume ratio. The relationship is much closer than that of the properties of the LV and aortic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)