Coronary artery impedance estimation based on the intravascular ultrasound technique and its experimental studies

In order to perform more reliable and comprehensive clinical description for the coronary's hemo-dynamics, ultrasound images, Doppler blood flow signals and blood pressure waveforms from the coronary artery were acquired using the intravascular ultrasound (IVUS) technique and blood pressure detection instruments. Here a modified active contour model was applied to estimate the lumen area of the coronary artery from IVUS images, and a method integrating the morphology and the dynamic programming was applied to extract the velocity information from the Doppler spectrogram. With the ECG as the synchronization, the blood volume waveform over a cardiac cycle was calculated. With the blood volume and pressure waveforms, the impedance of the coronary artery was obtained using the Fourier series. From the controlled experiments on pigs, it was seen that the impedance estimated using this approach can reflect the coronary artery's blood supply and reservation capability under various degrees of the microcirculation dysfunction of the coronary. With the further efforts in the research, the coronary impedance obtained by this method may become a significant parameter for the clinical diagnosis.