Abstract 15301: Effects of Surgical Arch Reconstruction and Shunt Type on Ventriculo-Arterial Coupling in Palliated Hypoplastic Left Heart Syndrome: Non-Invasive Assessment
Background: right ventricular dysfunction is an important contributor to mortality and morbidity in children with hypoplastic left heart syndrome (HLHS) and abnormal afterload can contribute to it.
Patients and methods: Ventriculo-arterial (VA) coupling was assessed prior to Fontan completion in 32 patients with HLHS (19 had modified Blalock-Taussig shunt and 13 Sano shunt at Stage 1). Cardiovascular magnetic resonance (CMR) data was analysed, deriving functional parameters as well as 3D anatomical volumes from which areas of transverse arch, isthmus and descending aorta were calculated. Coarctation indices were computed as the ratio of areas of the isthmus and a) the descending aorta (=CI1), b) the transverse, surgically enlarged arch (=CI2). Wave intensity analysis was performed using CMR data with an in-house written plug-in. Peaks of the forward compression and expansion waves (FCW and FEW) in early and late systole were surrogate indicators of ventricular systolic and diastolic function, respectively. The plug-in also yielded wave speed, from which distensibility was directly derived.
Results: Aortic distensibility (3.6±2.7 x10-3 1/mmHg), which was reduced in HLHS, was not associated with a greater time elapsed from stage 1 palliation (p=0.94), suggesting that loss of elasticity in the aorta occurs early but does not progress thereafter. CI1 was 1.0±0.4 and CI2 was 0.3±0.1; FCW did not correlate with CI1 (R=0.09,p=0.6), but was significantly related to CI2 (R=0.47,p=0.006). Patients with reduced ejection fraction (EF) exhibited larger ventricular mass (R=0.54, p=0.001). Furthermore, Sano shunt patients had lower EF (p=0.02) and a trend of 10% higher end-diastolic volume compared to mBT shunt patients. However, neither FCW nor FEW varied significantly between mBT and Sano shunt cohorts.
Conclusions: These data suggest that VA coupling i) is affected by aortic arch size mismatch, not aortic coarctation as defined by CI1, and ii) is not considerably affected by type of shunt placed at the Norwood operation and ventriculotomy-associated scarring and myocardial thinning.
- © 2013 by American Heart Association, Inc.