Windkessel Effect (and Large Artery Physiology)

Windkessel Effect Basic Details:

• Windkessel in German means 'air chamber'.
• Term implies an elastic reservoir in large arteries.

Windkessel Effect Mechanism:

• Distension of the aorta following ejection of blood from the left ventricle during systole.
• The distended aorta then recoils during diastole, smoothing out pressure & blood flow.
• The walls of large elastic arteries (eg. aorta, common carotid, subclavian, & their larger branches, plus pulmonary artery) contain elastic fibers which are composed of elastin.
• These same arteries distend when the blood pressure rises during systole & then recoil when the blood pressure falls during diastole. 
• The rate of blood entering these elastic arteries significantly exceeds that leaving them due to arterial peripheral resistance.
• This results in a net storage of blood during systole which unloads during diastole.

Windkessel Effect Accomplishes the following:

• Decreases pulse pressure during cardiac cycle.
• Increased efficiency of pumping of the left ventricle.
• Provides more continuous flow.
• Contributes to organ perfusion during diastole when cardiac ejection ceases.
• Specifically helps the perfusion of the coronary arteries during diastole.

Ageing & The Windkessel Effect:

• Diminution of the Windkessel effect occurs with age.
• Associated with the elastic arteries becoming less compliant.
• Pathologically related to 'hardening of the arteries' or arteriosclerosis where there is fragmentation & loss of elastin in the arteries.
• Clinically results in increased pulse pressure, systolic pressure & cardiac oxygen consumption for any given cardiac stroke volume.
• The consequences of these pathophysiological changes include greater risks for myocardial infarction, cardiac enlargement, heart failure, stroke, peripheral vascular disease & renal damage.

Tags: Aorta - Arteriosclerosis - Diastole - Elastic Fibers - Elastin - Pulse Pressure - Systolic Blood Pressure - Windkessel Effect - Systole - Vascular Disease
Posted by Medicalchemy
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