A Non-Invasive Study Using MR-Derived Wave Intensity Analysis to Highlight the Effect of Surgical Arch Reconstruction on Ventriculo-Arterial Coupling in Patients With Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS) is a congenital heart disease whose staged surgical palliation aims to progressively separate the systemic and pulmonary circulations. The first stage or Norwood procedure [1] involves surgical reconstruction of the aortic arch, usually with pulmonary homograft patch [2]. Recent evidence suggested that, because of this extensive reconstruction, HLHS patients have abnormal elastic properties [3] and reduced distensibility [4,5] of the ascending aorta. However, the impact of the reconstructed aorta and its abnormal elastic properties on ventricular mechanics, i.e. ventriculo-arterial coupling mismatch, has not been assessed. In the light of this mismatch, a change in impedance on the arterial side will reflect on the ventricular side and quantification of this phenomenon may provide mechano-energetic information for further understanding a complex physiology such as palliated HLHS with aortic arch surgical reconstruction. In this study we suggest that wave intensity analysis (WIA) is a valid method for studying ventriculo-arterial coupling, as WIA is a hemodynamic index able to assess the performance of the heart and its interaction with arterial system. Previously, distensibility quantification necessitated either of invasive [5] or cuff [4] arterial pressure monitoring, or multiple magnetic resonance (MR) images acquisitions for transit time wave speed calculation [6]. Instead, here we propose a non-invasive and semi-automated method based only on MR images analysis, with single slice analysis for estimate of local distensibility. The method, including WIA, was developed as a plug-in for DICOM viewer OsiriX, and applied to two cohorts of single ventricle patients.