Two-dimensional guided M-mode color tissue Doppler echocardiography in artificial preexcitation models

The purpose of this study was to analyze the left ventricular contraction patterns in artificial preexcitation models by using 2-dimensional guided M-mode color tissue Doppler echocardiography. Three types of preexcitation models were produced in 12 patients by right atrio-mitral annular sequential pacing, carried out at the left ventricular lateral, posterior, and posteroseptal walls. Tissue Doppler M-mode was recorded at anteroseptal, posterior, lateral, and posteroseptal sites in the parasternal short-axis view. The time interval from the onset of the QRS complex during sinus rhythm or from the annular pacing spike during fusion beats to the beginning of systolic motion was measured. During sinus rhythm, the time interval at the anteroseptal wall was shortest. During fusion beats, the time intervals at the mitral annular pacing sites were shortest. In preexcitation models, tissue Doppler M-mode could clearly distinguish the difference of left ventricular contraction patterns and detect the earliest contraction site of the left ventricle.