Localizing systolic ejection within a trans-esophageal CW Doppler ultrasound aortovelographic waveform

Localizing systolic ejection within trans-esophageal Doppler (TED) ultrasound aortograms is crucial for clinical application, but can be difficult to achieve especially during low flow states commonly encountered in critical care medicine. Termination of ventricular systole within the thoracic aorta is marked by the incisura, a transient, easily recognized on an intra-aortic pressure waveform but not on the non-invasive TED derived flow waveform. We have attempted to develop a new digital signal processing (DSP) strategy with the aim of recognizing physiologically relevant transients within quadrature demodulated Doppler ultrasound signals. We have applied our strategy to real aortic blood flow signals recorded during hypovolemia. Our new approach to TED quadrature demodulated signals shows how systole can be identified non-invasively and offers the real potential for refinement of the device.