REGISTRO Y CONTROL CONTINUO DEL pH PARA LA APLICACIÓN EN EL ESTUDIO DE LA CALCIFICACIÓN INVITRO DE UNA BIOPRÓTESIS DE VÁLVULA CARDIACA

Abstract

One of the most repeated problems when implanting cardiac valves, is the calcification of the tissue when they remain for a long time in the human body. Therefore the Criobiology and Biomaterials Department of the German University of “Reinischwestfälische Technische Hochschule Aachen” (RWTH) together with the Metronic Interprise, pioneer in the manifacturing of the proteinic valves are carrying out during some years studies to determine with accuracy the cause of the phenomenon. The study lies in subjecting 10 valves to an operation test during 8 weeks, equal to 24 millions of heart beatings to start the production of calcification and be able to determine its cause. These valves are all the time submerged in a liquid with similar characteristics to the human blood characteristics.
The first experiments were carried out without considering the acid degree of the liquid which should stay with a constant pH of 7.4. In these experiments it was not able to determine if the variation of the pH that the liquid presented had influenced on the calcification of the valves after the 8 weeks.
The present thesis shows a practical solution to this problem, by introducing a design whose goal is to measure and control the pH of the liquid used in the experiment, and so be able to discard the variation of pH in the calcification of the valves.
This thesis shows the details of the introduction of the measurer-controller of the pH likewise also of the program carried out in Visual Basic in charge of reading and processing the data given by the measurer.
The measurer-controller can measure and control the pH of any liquid, but it is designed to be used in the pH control of the liquid in which the valves are submerged when carrying out the test.
The correct functioning of the pH measurer-controller was tested in a simulated environment and although the design has a device for a measurer of conventional pH, a simulated sensor of pH was used in this case.