David Klemenc (2012) Development of a procedure for spatial reconstruction of coronary artery bifurcation on the basis of coronary angiogram images. EngD thesis.
Cardiovascular diseases are the most important cause of morbidity and mortality in the developed countries. It's estimated that about two million people die because of heart disease. Coronary artery disease (CAD) presents the most important part of cardiovascular diseases. Coronary arteries are conduits responsible for nutrition and oxygenation of heart muscle cells. Coronary bifurcations present special problem in CAD, because of high prevalence of stenoses - i.e. arteriosclerotic plaques. Bifurcation of coronary artery can be divided in three parts: proximal main artery (or main branch), distal main artery and side branch. The angles between branches are important as they dictate the way of dilatation and stenting: wiring of side branch can be difficult if the angle between distal main and side branch is greater than 90o, the same is true for stenting of ostial lesion of side branch; shift of carina can obstruct the ostial part of side branch after "provisional" stenting (i.e. stenting of proximal and distal part of main branch with covering of ostial part of side branch) if the angle is less than 40o-50o. Shallow angle between the proximal main vessel and side branch may be associated with higher incidence of side branch occlusion. However, shallow angle allows easier access for side branch wiring and stent delivery. Techniques that are currently proposed for determining the angle between arteries, forming the bifurcation, consider the widest angle in the least foreshortened projection. With 3-dimensional reconstruction of the bifurcation, which is the purpose of this work, we can accurately determine the angles between blood vessels forming the bifurcation, thus reducing the error that occurs due to subjective impression of the interventional cardiologist based on non orthogonal projection of the bifurcation. In the first chapter we describe the characteristics of coronary angiogram and the problems that arise due to the heart movements. Geometrical formulas, which will be used for 3-dimensional reconstruction of bifurcations are presented in second chapter. Next chapter is dedicated to the analysis of the distortion of the original angle in various projections. In the fourth chapter, we will gradually reconstruct the bifurcation, we'll start with the reconstruction based on projections without error and finish with the reconstruction of the bifurcation based on projections with multiple errors. The fifth and sixth chapters show a practical example reconstructing a bifurcation from two projections and the code that solves the problems mentioned up to this point. In conclusion, I found that it's possible to accurately construct a 3-dimensional model of coronary artery bifurcations by applying different standard 2-dimensional projections used during percutaneous coronary interventions.
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