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Right ventricular pacing and left ventricular filling pattern. An echo-Doppler study.

The influence of right ventricular pacing on left ventricular filling has not been completely clarified. The aim of the study was to analyze the possible alteration in and effects on left ventricular filling resulting from right ventricular pacing. The study population consisted of two groups; group A was comprised of 12 patients with a spontaneous left bundle branch block, and group B had 12 patients without left bundle branch block. All the patients underwent an interrogation of the mitral valve inflow by Doppler echocardiography, in order to measure isovolumic relaxation time, early and late peak velocity (E and A wave), E/A ratio and deceleration time. The study was performed at spontaneous rhythm and after, inhibition of the pacemaker. In group A, there were no changes in the Doppler parameters when passing from a spontaneous to an 80/min electrically induced rhythm. Analysis of group B revealed a statistically significant lengthening of IVR and Dec t with electrical stimulation. No statistically significant differences were found when we compared the Doppler parameters of the two populations at the same pacing frequency. Right ventricular pacing causes interventricular asynchrony and abnormalities in diastolic filling times, which resulted in a lengthening of either IVR and Dec t, simulating a pattern of abnormal relaxation.