Abstract 2458: Optimal Site Pacing in Children: Chronic LV Pacing Prevents the Loss in Function Associated with Chronic RV Pacing
Background: Chronic right ventricular (RV) pacing is associated with deleterious structural and functional outcomes in children and adults. Many animal studies showed acute hemodynamic benefit of left ventricular (LV) over RV pacing. The aim of this study is to compare the long-term effects of chronic RV and LV pacing in children with congenital or acquired AV-block with normal biventricular anatomy.
Methods: Retrospectively, echocardiographic data were collected obtained from children with surgically implanted epicardial RV (n=8, pacing duration 3.7±2.0 yr) and LV lateral wall pacing leads (n=8, pacing duration 3.6±1.7 yr) and from 18 healthy, age matched controls. End-diastolic (LVEDWT) and end-systolic LV wall thickness (LVESWT) were determined as the mean of values in 6 (pacing groups) or 4 (controls) regions on 2D-echocardiographic images. Similarly, on short axis views mean LV end-diastolic (LVEDD) and end-systolic diameter (LVESD) and fractional shortening (FS) were determined. LV dimensions were normalized to body surface area (BSA). QRS-duration was assessed as a measure of synchrony of electrical activation. P<0.05 was considered significant.
Results: Data are summarized in the table⇓. QRS-duration was similarly prolonged in the RV and LV pacing groups as compared with the control group. LVEDD/BSA was not different in the 6 regions within or between the groups. However, FS was significantly lower in the RV pacing group than in the LV pacing and control groups. This depressed systolic function was associated with a significantly larger LVESD/LVESWT and LVEDD/LVEDWT ratio in the RV paced patients. These ratios are measures of eccentricity of the LV and related to wall stress.
Conclusions: RV pacing in young children results, within 3 years, in significant deterioration of LV function and relative LV dilatation. These abnormalities can be prevented by positioning the pacing electrode at the LV lateral wall.