Ultrasonic 3D speckle tracking for assessment the effects of various cardiac pacing modes on left ventricular function of healthy canine

Abstract

Objective To evaluate the effects of various cardiac pacing modes on mechanical synchrony of left ventricular wall and left ventricular function using ultrasonic 3D speckle tracking imaging.Methods Ten healthy open—chest beagles left ventricular full volumetric real—time imaging in a completed cardiac cycle were acquired respectively during baseline(BASE)and right ventricular apex pacing(RVAP),left ventricular apex pacing(LVAP),left ventricular lateral wall pacing(LVLP)state.Left ventricular pressure—time sequence curve was recorded simultaneously for achieving left ventricular ejection pressure and the maximal upstroke velocity of left ventricular systolic pressure.Radial 3D strain maps and radial 3D peak strain of left ventricutar wall,and left ventricular end systolic volume,end diastolic volume,stroke volume,ejection fraction,cardiac output of different states were extracted respectively using ultrasonic 3D speckle tracking analysis software.The radial 3D strain synchrony of left ventricular wall during different states was qualitatively observed and compared.The t test,chi square test and linear correlation analysis was applied respectively for analyzing the quantitative parameters.Results ①The radial 3D strain asynchrony of different myocardial segments of left ventricular wall during LVAP or LVLP was worse than that during RVAP.②There were more myocardial segments of left ventricular wall which radial 3D peak strain degraded significantly during LVAP or LVLP than those during RVAP(9/16 vs2/16,P<0.05).③To be compared with RVAP,left ventricular stroke volume,ejection fraction,cardiac output and the global radial 3D peak strain of left ventricular wall were degraded during LVAP or LVLP(P<0.05).④There were statistic significant linear correlations between the global 3D peak strain of left ventricular wall and left ventricular stroke volume,and left ventricular ejection fraction,and cardiac output in different states(r=0.781～0.984,P<0.05).Conclusions As far as the destructive effect on the mechanical synchrony of left ventricular wall and left ventricular function of healthy canine is concerned,LVAP or LVLP mode is more harmful than RVAP mode. Key words: Echocardiography,three-dimensional; Cardiac pacing,artificial; Ventricular function,left; Speckle tracking imaging