P766Ventricular interaction plays a major role in left ventricular systolic synchrony of pediatric transplanted hearts: a three dimensional echocardiography study.

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Introduction: three-dimensional echocardiography (3D-e) allows evaluation of segmental LV contraction on a single cardiac beat.No data are available on the prevalence of LV dyssynchrony in pediatric population with heart transplant(c-Tx)and normal EF obtained by 3D echocardiography.Methods: 55c-Tx patients and 10 healthy volunteers underwent standard 2D and 3D echocardiographic examination with analysis of LV synchrony (iE33, Philips). LV systolic contractile synchrony was studies by 3D-e acquisition of the apical view.Images were analyzed offline and percent delay in segmental contractile peak was used to derive LV synchrony(3D-SSI%).Data from the c-Tx were compared to the control group as well as to previously published partition values, to identify patients with clear-cut LV dyssynchrony (defined as 3D-SSI%>8.3%).Results: Patients with rejection,coronary artery occlusion,EF< 55%,inadequate echocardiographic images and/or with transplant performed less than 4 months beforewere excluded.Accordingly data on 25 c-Tx were available for analysis.Mean time from heart transplant was 6 years.No differences were observed among groups in LV ejection fraction(62% vs 63%), fractional shortening, diastolic mitral inflow pattern or mitral E/e' ratio(all p=ns). In c-Tx, mean 3D-SSI% values were significantly higher as compared to normal controls (4.5% vs 2.5%;p<0.05).Accordingly while in the control group none of the patients showed LV dyssynchrony,in the c-Tx group LV dyssynchrony could be identified in 20% of the patients (n=5).As compared to c-Tx with normal 3D-SSI%,those with evidence of dyssynchrony were slightly older (p=0.05) without significant differences in LV systolic or diastolic functional parameters(including 3D-EF,3D-fractional shortening,diastolic mitral inflow pattern or mitral E/e' ratio).In contrast patients with clear-cut LV dyssynchrony showed a significant reduction in parameters of right ventricular(RV)function,including RV fractional shortening(46% vs 40%)and tricuspid annular plane systolic excursion(15mm vs 10mm; both p<0.05).In multiple binary logistic regression, independently of EF,RV fractional shortening was the major determinant of LV dyssynchrony (r=−0.3; p<0.05).Conclusions: Despite normal ejection fraction,a significant proportion of pediatric c-Tx patients show evidence of clear-cut LV dyssynchrony.LV dyssynchrony is associated with depressed RV function,independently of indices of LV diastolic and/or systolic function.Our findings show a major effect of RV function on LV synchrony in c-Tx,suggesting a significant interaction between LV and RV function in these patients.

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