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Arterial stiffness may also affect the time at which pulse wave reflections return to the heart. As the pulse wave travels through the circulation it undergoes reflection at sites where the transmission properties of the arterial tree change (i.e. sites of impedance mismatch).
The theory of the velocity of the transmission of the pulse through the circulation dates back to 1808 with the work of Thomas Young. [9] The relationship between pulse wave velocity (PWV) and arterial wall stiffness can be derived from Newton's second law of motion (=) applied to a small fluid element, where the force on the element equals the product of density (the mass per unit volume ...
Compliance diminishes with age and menopause. Arterial compliance is measured by ultrasound as a pressure (carotid artery) and volume (outflow into aorta) relationship. [5] Compliance, in simple terms, is the degree to which a container experiences pressure or force without disruption. It is used as an indication of arterial stiffness.
The high pulse pressure in elderly people with hypertension or isolated systolic hypertension is explained by increased arterial stiffness, which typically accompanies aging and may be exacerbated by high blood pressure. [81] Many mechanisms have been proposed to account for the rise in peripheral resistance in hypertension.
The stiffness of the aorta is associated with a number of diseases and pathologies, and noninvasive measures of the pulse wave velocity are an independent indicator of hypertension. Measuring the pulse wave velocity (invasively and non-invasively) is a means of determining arterial stiffness .
Pulse pressure is calculated as the difference between the systolic blood pressure and the diastolic blood pressure. [3] [4]The systemic pulse pressure is approximately proportional to stroke volume, or the amount of blood ejected from the left ventricle during systole (pump action) and inversely proportional to the compliance (similar to elasticity) of the aorta.
The arterial compliance - the amount of tension produced per stretch of arteries, decreases with age, and the stiffness of arteries increases with age. [3] The structural change in blood vessels causes the elderly to be more susceptible to hypertension, which leads to complications in arteries, the heart and even the brain.
This is probably due to vascular calcification causing increased arterial stiffness, increased pulse pressure and resulting in exaggerated damage to the heart and kidneys. [12] The clinical symptoms of Mönckeberg's arteriosclerosis are similar to giant cell arteritis in which the two can be mistakenly interchanged.