Cardiac function, fiber shortening and dynamic geometry

Many models for the study of the pump function of the heart emphasize the importance of cardiac geometry and detailed dimensional data. Because of the lack of accurate measuring techniques, approximate geometries such as shells of revolution have been applied. In this study, methods are presented that measure the dynamic geometry of the working, isolated canine heart by means of ultrasound- velocity tomography techniques. In addition, cardiac dimensions, intramural deformations, and fiber shortening have been measured dynamically in the in situ canine heart throughout the cardiac cycle with implanted tadiopaque markers and biplane roentgen techniques. Results of regional contraction and relaxation patterns are presented. Epicardial fiber shortening between apex and base were computed and found to be dependent on the duration of the preceding RR interval

A measurement system for left ventricular volume determination

A system for measurement of left ventricular volume is described, in which biplane angiocardiograms are recorded on a video disk. Into the video frames, ECG and pressure curves are coded as well as time references, values of 5 other quantities among which the time elapsed since the preceding R wave sampled at the moment of the X-ray flash, and 1000 characters of alphanumeric information. Videosubtraction is used as a preprocessing technique, after which the ventricular contours are drawn with a light-pen and retained in a digital memory. Via a video computer interface the contour data are fed to a PDP-15 computer which calculates the ventricular volume according to a geometrical model based on measurements of casts of the left ventricle