Frequent Dilatation of the Descending Aorta in Children With Hypoplastic Left Heart Syndrome Relates to Decreased Aortic Arch Elasticity

Abstract

BackgroundPatients with hypoplastic left heart syndrome after a Norwood operation show dilatation and reduced distensibility of the reconstructed proximal aorta. Cardiac magnetic resonance imaging (CMR) and angiographic examinations indicate that the native descending aorta (DAo) is also dilated, but this has not been studied in detail.Methods and ResultsSeventy‐nine children with hypoplastic left heart syndrome in Fontan circulation (aged 6.3±3.2 years) and 18 control participants (aged 6.8±2.4 years) underwent 3.0‐tesla CMR. Gradient‐echo cine and phase‐contrast imaging was applied to measure cross‐sectional areas (CSAs), distensibility, pulse wave velocity, and the incremental elastic modulus of the thoracic aorta. CSA of the DAo in patients was also compared with published percentiles for aortic CSA. Patients had significantly larger CSA of the DAo at the level of pulmonary artery bifurcation (229.1±97.2 versus 175.7±24.3 mm/m2, P=0.04) and the diaphragm (196.2±66.0 versus 142.6±16.7 mm/m2, P<0.01). In 41 patients (52%), CSA of the DAo was >95th percentile level for control participants, and the incremental elastic modulus of the aortic arch and the DAo was higher than in patients with normal CSAs (arch: 90.1±64.3 versus 45.6±38.9 m/s; DAo: 86.3±53.7 versus 47.1±47.6 m/s; P<0.01). Incremental elastic modulus of the aortic arch and the DAo correlated with the CSA of the DAo (arch: r=0.5; DAo: r=0.49; P<0.01).ConclusionsChildren with hypoplastic left heart syndrome frequently show dilatation of their DAo associated with increased stiffness of the aortic arch. Higher aortic impedance increases the afterload of the systemic circulation and likely contributes to the burden of the systemic right ventricle.

Aortic stiffening and its impact on left atrial volumes and function in patients after successful coarctation repair: a multiparametric cardiovascular magnetic resonance study

“…These findings do not contradict one another. Rather, they demonstrate that bioelasticity, in terms of the elastic modulus of the carotid arteries was not impaired, and the higher PWV in patients can be attributed to the increased carotid wall thickness [ 35 , 36 ]. For comparisons of PWV’s the effect of vessel wall thickness needs to be taken into account [ 36 ].…”

Determinants of Aortic Size and Stiffness and the Impact on Exercise Physiology in Patients After the Fontan Operation

“…Finally, the present study did not include postFontan patients with hypoplastic left heart syndrome; therefore, our data may not be applicable to the pathophysiology of those with hypoplastic left heart syndrome. 52) Conclusions: Fontan patients have a significantly stiffer dilated aAO with a rapidly tapering smaller dAO that is closely associated with exercise pathophysiology. In addition to intrinsic aortic structural abnormalities and individualized medical history, current heart failure severity as well as traditional cardiovascular risk factors, such as inflammation and impaired glucose metabolism, are also involved in the aortic structural and functional abnormalities (ie, Fontan aortopathy), suggesting that a lifelong meticulous management strategy for vascular health is mandatory to improve long-term outcomes in Fontan patients.…”

Mechanical Concepts Applied in Congenital Heart Disease and Cardiac Surgery

“…In the congenital realm, decreased aortic arch elasticity was found to be related to dilation of the descending aorta in children with hypoplastic left heart syndrome [35]. Distensibility of a vessel might have a great significance in the Fontan circulation, where flow in the conduit is greatly related to intrathoracic pressure changes during ventilation, a phenomenon known as "lung pump.…”