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This paper describes a method to calculate the systolic/diastolic indices of the blood flow that pass through an artery or vein under test. The method analyzes the Doppler and the ECG signals, associating and synchronising them in order to calculate the indices. The maximum of the R and T waves, are calculated using a continuous wavelet transform. Simultaneously, the pseudo-instantaneous mean frequency is calculated from the Doppler blood flow signal. A projection of the R and T wave mark over the pseudo-instantaneous Doppler mean frequency curve is used for computing the indices. The paper shows preliminary results from real signals obtained from a carotid artery, an humeral artery and an aortic artery, demonstrating the effectiveness of the method. Further results will be obtained through a formal experimental protocol during coronary bypass surgery.

The design and construction of an ultrasonic Doppler transducer with a fixed angle for medical application using a novel acoustic matching material are described. This transducer was constructed using an 8 MHz commercial piezoelectric ceramic (PIC255) and REXOLITE which is an excellent acoustic matching material. The objective of the present work was the design and construction of an ultrasonic transducer using REXOLITE, this transducer will be part of a Doppler blood flow measurement system, the novelty of this transducer is that it includes an internal angle (45°). The resonance frequency is around 5 MHz. The transducer must work with the associated electronics using quadrature demodulation generated for the ultrasonic Doppler blood flow signal.