Abstract:

Abstract:Objective To study the mechano-electric delay phenomenon,an unrecognized phenomenon and its mechanism in cardic cycle with M-mode echocardiography and tissue Doppler imaging (TDI). Methods The mitral valve closure point to the onset of QRS complex by M-mode and TDI（C-Q interval,C’-Q interval）and the onset of isovolumic contraction wave S1 to the onset of QRS complex（S1-Q interval）by TDI of 26 patients with first-degree AV block were obtained,as well as the displacements and strains of myocardium in C’-Q interval and  S1-Q interval. Results The  onset of S1 of 26 patients were ahead of the onset of QRS complex,furthermore,the mitral valve closure point of 23 patients were ahead of QRS complex too. The obvious displacements and strains of myocardium in C’-Q interval and S1-Q interval could be seen. Conclusion Because of  passive contraction not controlled by electrical signals,another contraction fashion except active contraction,there should be exist a mechano-electric delay phenomenon in cardic cycle.

Key words: echocardiography;mechano-electric delay;passive contraction