Reduced ascending aorta distensibility relates to adverse ventricular mechanics in patients with hypoplastic left heart syndrome: Noninvasive study using wave intensity analysis

Objective: To evaluate the aortic arch elastic properties and ventriculoarterial coupling efficiency in patients with single ventricle physiology, with and without a surgically reconstructed arch. Methods: We studied 21 children with single ventricle physiology after bidirectional superior cavopulmonary surgery: 10 with hypoplastic left heart syndrome, who underwent surgical arch reconstruction, and 11 with other types of single ventricle physiology but without arch reconstruction. All children underwent pre-Fontan magnetic resonance imaging. No patient exhibited aortic recoarctation. Data on aortic wave speed, aortic distensibility and wave intensity profiles were all extracted from the magnetic resonance imaging studies using an in-house-written plug-in for the Digital Imaging and Communications in Medicine viewer OsiriX. Results: Children with hypoplastic left heart syndrome had significantly greater wave speed (P = .002), and both stiffer (P = .004) and larger (P < .0001) ascending aortas than the patients with a nonreconstructed arch. Aortic distensibility was not influenced by ventricular stroke volume but depended on a combination of increased aortic diameter and abnormal wall mechanical properties. Those with hypoplastic left heart syndrome had a lower peak wave intensity and reduced energy carried by the forward compression and the forward expansion waves, even after correction for stroke volume, suggesting an abnormal systolic and diastolic function. Lower wave energy was associated with an increased aortic diameter. Conclusions: Using a novel, noninvasive technique based on image analysis, we have demonstrated that aortic arch reconstruction in children with hypoplastic left heart syndrome is associated with reduced aortic distensibility and unfavorable ventricular-vascular coupling compared with those with single ventricle physiology without aortic arch reconstruction. (J Thorac Cardiovasc Surg 2012; 144:1307-14)