Remodeling of the Maternal Mitral Valve During Pregnancy: A Recapitulation of Fetal Development?

Pregnancy involves volume overload, cardiac enlargement, and heart valve remodeling. The mitral remodels via increased leaflet area, composition, mechanics—and remarkably an increase in the number of chordae attachments. This is striking contrast to pathological remodeling as failure. Indeed, we hypothesize that maternal during pregnancy recapitulates fetal developmental mechanisms. To test this hypothesis, compared structural changes developing gestation (respectively) using a bovine model. Maternal hearts were obtained from local abattoir, pregnancy/gestational time calculated crown-rump length. We measured anterior size, tendineae attachments, collagen content (newly synthesized mature forms), fibril diameter crimp Chordae attachments growth/expansion both valves. numbers fetus at full term comparable those adult, suggesting chordal multiplication ceases birth—despite continuing postnatal growth. In valves, accumulated faster than leaflets enlarged, resulting tissue concentration collagen. Collagen was maintained, despite rapid increases size Paradoxically, amount newly remained unchanged leaflets, crosslinking upregulated both. Anatomical parallel occurring simultaneously fetus. may involve re-activation