P664Systemic right ventricle remodelling patterns and systolic function.


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Abstract

Background: Following atrial switch procedure due to complete transposition of the great arteries right ventricle (RV) is subjected to systemic blood pressure and undergoes significant remodeling. However little is known about patterns of RV wall hypertrophy in this setting.Methods: In 33 patients following atrial switch we measured diastolic right ventricular diameter (RVD) and intraventricular (IVS) and free wall (FW) thickness [compact (FWC) layer + trabeculated (FWT) layer] at midventricular level. Relative wall thickness (RWT) was calculated as FW+IVS/RVD. Patterns of RV hypertrophy were assessed qualitatively with respect to location (apex vs free wall mid-basal segments vs interventricular septum) and intensity (mild, moderate, severe).Results: In 27% patients FW hypertrabeculation was limited to RV apex and nearly absent in mid-basal FW. FW mid- basal hypertrabeculation was mild in 30% patients and moderate-to-severe in 43%. IVS hypertrabeculation was universally absent. RVD was 48.1±7.5 mm, IVS was 6.3±1.4 mm, FWC layer was 3.6±1.0 mm and FWT layer was 7.3±2.9 mm (10.9±3.3 combined FW). RV RWT was 0.36±0.09. RV RWT >0.44 was present in 21% of patients. Compared to patients with RWT ≤0.44, patients with RWT >0.44 had significantly better RV systolic function (fractional area change 0.47±0.6 vs 0.40±0.9; p<0.05).Conclusion: In spite of being subject to systemic pressures RV walls are not significantly thickened. RV concentric hypertrophy (RWT>0.44) is associated with better RV systolic function, but is relatively infrequent. Its absence may contribute to late RV systolic dysfunction in these patients. Distinct hypertrophy pattern may explain apparent lack of efficacy of classic heart failure drugs used to prevent or reverse ventricular remodeling.

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