Abstract
Right ventricular apical pacing alters impulse conduction producing an intraventricular desynchronization that could be detrimental for LV function. Direct His bundle pacing (DHBP) represents a novel approach to cardiac pacing in pts with normal His-Purkinje activation because it maintains or restores the physiological activation of the ventricular muscle during cardiac pacing.
13 pts (mean age 76±3 years; 2 females; QRS duration 118±24 ms; LV EF% 60±11; LV end-diastolic volume 61±22 ml/m2) have been investigated. At baseline and after DHBP Tissue Doppler Imaging was performed to evaluate the intraventricular dyssynchrony [defined as the interval between the earliest LV wall motion and the latest (intra LV delay) or as standard deviation (SD, modified Yu index) of all time intervals]. Tei index, E/A ratio, dP/dT, MR (mitral regurgitation-diameter of vena contracta) were also obtained. Baseline intra-LV desynchronization (intra-LV delay above 40 ms) was observed in 2 pts with normal QRS and in all 4 pts who had intraventricular conduction delay (QRS > 120 ms).
in table are displayed the values at baseline and after DHBP:
After DHBP only one pt with baseline QRS >120 ms maintained an intra-LV desynchronization. Moreover both Tei index and dP/dT improved but not significantly. Conclusion: DHBP maintains the normal activation and contraction of ventricular myocardium.
