Research On Sinoatrial Node Based On Intracardial Doppler Tissue Imaging

Sinoatrial node (SAN) is the pace maker of the heart and the origin of the cardiac conduction system. It is very important to the normal functioning of the heart. Though there is much research on its morphology and electrophysiology in vitro, there's no research on its movement and activation in vivo.A method has been developed to quantitatively analyze SAN based on intracardial Doppler Tissue Imageing(DTI) in the present thesis. An ultrasound intracardial catheter with all DTI functions was used to image the SAN via the superior vena cava (SVC) in animal experiments. The color information in the Doppler Tissue Acceleration(DTA) image sequences was then separated and mapped to quantitative acceleration values. Finally several statistic parameters, include mean values, variances, time curves, and cumulative distribution function (CDF) of acceleration were calculated to describe the movement of the SAN.Complete cycles of a SAN excitation are observed. The estimated tune-acceleration curve of the SAN is remarkably similar to the ECG curve. It implies that tissue movement of a SAN is highly correlated with its electrical activities. The experiments also show that the CDFs of the accelerations have strong associations with different phases of a cardiac cycle. It is demonstrated that the method has great potential to characterize SANs, which may provide a new way to characterize cardiac activities. None of the research has been reported before.