Abstract

A computer model of the left ventricular (LV) epicardial surface was developed from Jang’s truncated ellipsoidal model, which has a minor to major axis ratio of 6:10. The model was applied in calculating the area of a segment of the myocardium, jeopardized by an impending occlusion of its associated artery. The endangered segment of the LV muscle was also visualized in different projections by rotations in three space and graphical displays simulating the three dimensions.

The area formula for the surface of the ideal model , a truncated prolate spheroid, was derived and used in producing maps for manual calculations of the coronary distribution fraction (CDF). These maps were also used as the correct or theoretical values in testing the reliability of the method to obtain CDF values by the computer program developed in this project.

The access to a computer made it feasible to make the ideal model more realistic by the single assumption that each cross section of the ventricle is a circle and each slice is a truncated cone. The formula for calculation of the surface area of a truncated cone was derived and is used in computing the total area of the LV epicardium by means of a progressive slicing method using 1 mm thick slices.

For an arbitrary coronary distribution zone (CDZ), the lateral coronary spread (LCS), occupying a part of each slice, is used to compute the coronary distribution area (CDA) of the slice. The total CDA of the entire CDZ is added up as the process is carried through. The CDF is computed as the ratio between the CDA and the total LV area thus obtained.

The computer program also provides for a slanted aortic end of the LV.

The reproducibility of this method to calculate the CDF was verified on a set of differently sized and arbitrarily shaped CDZs and ventricles.

The program can also calculate the LV muscle mass if so desired.

This part of the project was written in the FORTRAN and BASIC languages for a DGC Eclipse minicomputer and a Z-80 based microcomputer respectively, and the data from the tracings of the RAO-30° projection of a coronary angiogram were entered via a Summagraphics magnetic digitizer tablet.

The project was extended on the minicomputer system to include a 3-dimensional graphical representation on a HP 1310 A CRT x-y display with a free rotation of the ventricle in order to better visualize a certain CDZ in study. Two types of rotation were developed, one about the major axis of the LV and the other about the long axis of the patient’s body. The software program was specifically designed for the rotation and display of this particular object with a CDZ specifically marked in both the visible and the hidden hemisphere. The structure of the graphics program was also designed so as to use only main memory for fast processing and image reconstruction.

In the rotation about the LV major axis the bent axis of a realistically shaped ventricle was preserved. In the other type of rotation the "clinical" ventricle was mapped onto a more ideal model with a straight major axis.

The graphical part of the project is intended for instructional use. It also makes it possible, by an interaction during runtime, to improve the input tracings by retracing them till they match other available data.

The computer program has been used in a few clinical cases and to a larger extent in several research projects which have been presented at different national and international medical symposia. The computer method as such has also been presented at several symposia.

A separate computer program to produce diagrams of wall motion, ejection fraction (EF) and left ventricular end diastolic pressure (LVEDP) as functions of infarct size, or CDF, has been developed. This program requires statistically significant amounts of data of a specific category of patients. These data can be filed selectively during the operation of the first program. The latter program was tested on the data of 35 patients who had coronary angiograms revealing a total occlusion of the left anterior descending (LAD) artery. It is expected that, as more cases become available, these diagrams will be improved and will be used to predict the outcome of an impending occlusion of a coronary vessel, and thus to aid the physician in making decisions so as to prevent such an event.

Department

Mathematical Sciences

School

Graduate School

First Advisor

Ivan R. Neilsen

Second Advisor

Geun C. Jang

Third Advisor

C. Duane Zimmerman

Fourth Advisor

Melvin P. Judkins

Fifth Advisor

S. Andrew Yakush

Degree Name

Doctor of Philosophy (PhD)

Degree Level

Ph.D.

Year Degree Awarded

1980

Date (Title Page)

12-1980

Language

English

Library of Congress/MESH Subject Headings

Coronary Vessels; Heart Ventricle; Models, Cardiovascular

Type

Dissertation

Page Count

xi; 261

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

Download

Share

COinS