Pulmonary artery conduit in vivo dimensional requirements in a growing ovine model: comparisons with the ascending aorta.

BACKGROUND AND AIM OF THE STUDY: The pulmonary trunk (PT) structure and function are abnormal in multiple congenital cardiovascular diseases. Existing surgical treatments of congenital malformations of the right ventricular outflow tract and PT do not provide a long-term replacement that can adapt to normal growth. Although there is strong interest in developing tissue-engineered approaches for PT conduit replacement, there remains an absence of any complete investigation of the native geometric growth patterns of the PT to serve as a necessary benchmark.
METHODS: Eleven Dorset sheep (aged 4-12 months) underwent a single cardiac magnetic resonance imaging study, from which luminal arterial surface points were obtained using a novel semi-automated segmentation technique. The three-dimensional shapes of the PT and ascending aorta (AA) were measured over the same time period to gain insight into differences in the geometric changes between these two great vessels.
RESULTS: The volumetric growth of the PT appeared to be a linear function of age, whereas its surface geometry demonstrated non-uniform growth patterns. While tortuosity was maintained with age, the cross-sectional shape of the main pulmonary artery (MPA) evolved from circular in young animals to elliptical at 12 months. In addition, the distal MPA near the pulmonary artery bifurcation tapered with age.
CONCLUSION: It can be concluded that postnatal growth of the PT is not a simple proportionate (i.e. isotropic) size increase, but rather exhibits complex three-dimensional geometric features during somatic growth.