Abstract
From a law of physics, it is obvious that the momentum of blood ejected from heart during systole can be divided into two forms. The one is the momentum of blood running away distally and the other is that of the aortic root and blood in it. The motion of aortic root is related to the stroke volume by the equation of SV∝ D2Vao1/2× AOT, where D is the diameter of the aortic root, Vao is the mean velocity of the anterior wall during systole and AOT is the duration of aortic valve opening. Stroke volume estimated by the present method was found to be highly correlated with the stroke volume measured by the thermodilution method (r=0.81, p<0.001). A similar correlation was also observed with stroke volume determined from the left ventricular dimensions in an ordinary manner. Since the parameters that appeared in the present method were not directly affected by the mode of heart contraction, such as symmetrical or asymmetrical, it may be useful to determine stroke volume even in a heart contracting asymmetrically.
