Visual measurement of any shape of the flaccid membrane of the extracorporeal pneumatic heart assist pump

Abstract

The new visual method has been invented in order to measure the stroke volume of the extracorporeal pneumatic heart assist pump. Heart pumps of this type have a pneumatic chamber and a blood chamber separated by a flaccid membrane. Equipping the heart pump with a miniature camera makes it possible to observe the surface of the membrane from the pneumatic chamber side without obstructing its normal operation. The momentary shape of the flaccid membrane affects the volume of the blood chamber. The essence of the used measurement method is to observe a surface of the membrane using a camera and to determine the shape of this membrane in the actual 3-dimensional space, only on the basis of a one-shot image. This method works due to markers arranged on the surface of the membrane from the pneumatic chamber side. In the measurement, the image processing and analysis techniques are used. The difficulty of the accuracy verification of the shape mapping is that heart assist pump fitted with a flaccid membrane has only two membrane states with a known mathematical description. Research has already been conducted to verify the method for the extreme states and it has produced very good results. Invented new technique to 3D modeling of any shape of the flaccid membrane with well-known geometric dimensions allowed verifying the method for any shape of the membrane. The real membrane was replaced in sequence with four different rigid models with the known geometric dimensions. Results obtained in the study were presented.