STUDY OF CARDIAC STRUCTURES IN RELATION TO THE PERICARDIAL CAVITY FORTOTAL ARTIFICIAL-HEART IMPLANTATION

To enhance the design of the completely implantable total artificial h eart (TAH), we developed a coordinate system that expresses the geomet ry of the heart, including that at the interface with the TAH and that of the pericardial cavity. This coordinate system (ventricular coordi nate system) was developed using 3D images of the heart which were obt ained from magnetic resonance images. The origin is located on the cen troid of the mitral annulus at 25 ms delay from the ECG R wave (MO), a nd the y axis is the axis from MO to the apex at 25 ms delay (ApexO). The x-y plane includes MO, ApexO, and the centroid of the tricuspid an nulus at 25 ms delay. Since the y axis expresses the apical orientatio n of the heart, data using this coordinate system are not affected by individual variation in heart orientation. Heart geometry data were ob tained in 5 normal subjects. Compared with that using the coordinate s ystem based on the thoracic wall, the expression of the data of interf ace geometry for the heart and the TAH is simplified when the ventricu lar coordinate system is used. A method of expressing the geometry of the pericardial cavity using the ventricular coordinate system is also proposed. These methods may be applicable in obtaining data in patien ts suffering from cardiomyopathy.