- Increased cardiac workload by closure of the ductus arteriosus leads to hypertrophy and apoptosis rather than to hyperplasia in the late fetal period. van den Hoff, M.J., Deprez, R.H., Ruijter, J.M., de Boer, P.A., Tesink-Taekema, S., Buffing, A.A., Lamers, W.H., Moorman, A.F. Naunyn Schmiedebergs Arch. Pharmacol. (2004)