This paper sets out and presents a new approach to determine the stroke volume of the artificial ventricle. The stroke volume of the chamber is one of the basic heart function parameters. For the artificial heart assist purpose, in the study this value is calculated based on the mapped shape of the flaccid membrane of the extracorporeal pneumatic heart assist pump. This is a continuation of the earlier work on the use of image processing and analysis techniques to determine the membrane shape and the stroke volume of an artificial ventricle. The study focused on the determining the stroke volume using the numerical integration method. To do this, the membrane shape in the actual dimensions in millimetres is first mapped, and then a double integral under this surface is calculated. The comparison of different ways of numerical integration for different sizes of the measurement matrix as well as the obtained results were presented.