Solving practical issues of a portable Doppler Ultrasound system for blood flow assessment during coronary graft surgery

This paper presents some practical issues regarding the development of a dedicated Doppler Ultrasound system (DUS) for the assessment of blood flow signal on coronary grafts during heart surgery. The DUS is composed of several processing units. This paper concentrates on front-end units: the transducer and a particular issue of the software interface for clinical evaluation, the noise cancellation technique (NCTech). The experimental set-up implemented to evaluate the transducer response is presented. The procedure employed to eliminate the noise components embedded in the DUS data is described. Each of these units was primarily tested in laboratory. Results show their effectiveness in achieving their specific goals. Comments on the overall system´s performance are presented denoting the usefulness of such dedicated DUS during bypass assessment at heart surgery.