page_title: Windkessel effect
section_title: Applications
hierarchical_section_title: Windkessel effect / Applications
caption_attribution_description: The image shows the pressure in the aorta (red line) and the left ventricle (blue line) over two cardiac cycles, as well as the systolic pressure and diastolic pressure.
context_page_description: Windkessel effect is a term used in medicine to account for the shape of the arterial blood pressure waveform in terms of the interaction between the stroke volume and the compliance of the aorta and large elastic arteries and the resistance of the smaller arteries and arterioles. Windkessel when loosely translated from German to English means 'air chamber', but is generally taken to imply an elastic reservoir. The walls of large elastic arteries contain elastic fibers, formed of elastin. These arteries distend when the blood pressure rises during systole and recoil when the blood pressure falls during diastole. Since the rate of blood entering these elastic arteries exceeds that leaving them via the peripheral resistance, there is a net storage of blood in the aorta and large arteries during systole, which discharges during diastole. The compliance of the aorta and large elastic arteries is therefore analogous to a capacitor.
  The Windkessel effect helps in damping the fluctuation in blood pressure over the cardiac cycle and assists in the maintenance of organ perfusion during diastole when cardiac ejection ceases.
context_section_description: These models relate blood flow to blood pressure through parameters of R, C (and, in the case of the four-element model, L). These equations can be easily solved (e.g. by employing MATLAB and its supplement SIMULINK) to either find the values of pressure given flow and R, C, L parameters, or find values of R, C, L given flow and pressure. An example for the two-element model is shown below, where I(t) is depicted as an input signal during systole and diastole. Systole is represented by the sin function, while flow during diastole is zero. s represents the duration of the cardiac cycle, while Ts represents the duration of systole, and Td represents the duration of diastole (e.g. in seconds).
caption: Graph Evaluating Systole and Diastole Pressure
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