Assessment Of Regional Myocardial Function In Patients With DDD Pacing By Strain Rate Imaging

Objective To assess by strain rate imaging (SRI) the effect of atrio-ventricular delay (AVD)on regional left ventricular systolic long axis function as well as global left ventricularsystolic function in patients with dual-chamber pacemakers in the DDD mode, then discussits clinical value. Methods In 40 patients with complete atrioventricular block anddual-chamber pacemakers in the DDD mode, the AVD was programmed at 70, 110, 150, 190and 230ms, at a fixed rate of 70 min^-1, Using Color tissue Doppler imaging to acquire theimages in the apical 4-chamber, 2-chamber and long-axis views in each pacing modeselected, then use strain rate and strain Q-analyze to measure the peak strain rate of systolic(SRs), and the peak strain of systolic (S) along the left ventricular long axis in basical,middle and apical of anteroseptal, posterior, anterior, inferior, posteroseptal and lateral. Todetermin left ventricle stroke volume using the dimension of left ventricle outflow tract andtime velocity integral. Result In all the eighteen myocardial segments anylized, the SRs andS was highest when AVD=150ms (F=3.07～4.84,3.18～21.05, P＜0.01). Left ventriclestroke volume was maximum also at AVD=150ms. Conclusions In patients withdual-chamber pacemakersin the DDD mode, different AVD affects regional left ventricularsystolic long axis function and global left ventricular systolic function. Measuring SRs and Sof left ventricle segments is helpful to determine the optimal AVD in individual patients.