Assessment of Arterial Elasticity by Cardiovascular MRI.

Although some of the energy of left ventricular contraction produces forward blood flow during systole, the majority is briefly stored as potential energy in the distended arteries. During diastole, this energy is then reconverted into forward flow as the arteries contract (1,2). This serves to ease the load on the left ventricle, promote coronary artery perfusion, and maintain forward flow to the peripheral vessels. In Otto Frank's original "Windkessel" model (3), the arterial system acts as an elastic chamber in which diastolic pressure decays exponentially with a time constant determined by total arterial resistance and capacitance or compliance. Later refinements to this model include the addition of an inductance, or blood inertia, term and the division of the arterial tree into smaller Windkessel elements in analogy to a transmission line (4,5). Systemic arterial compliance is dominated by the aorta, which contributes over 60% of the total value (6). [ABSTRACT FROM AUTHOR]