Fluid flow shapes hearts

The creation of a normal heart involves a genetic programme, mechanical stimuli, and the cellular processes that link them, but the influence of factors such as blood flow on heart development has been unclear. In the January 9 Nature, Jay R. Hove and colleagues at the California Institute of Technology, Pasadena, USA, show that intracardiac fluid forces are an essential epigenetic factor for embryonic cardiogenesis (Nature, 421:172-177, January 9, 2003).

Hove et al. performed quantitative in vivo imaging analyses of intracardiac flow forces in zebrafish embryos. They observed the presence of a high-shear, vortical flow at two key stages in the developing heart, and predicted flow-induced forces much greater than might have been expected for micro-scale structures at low Reynolds numbers. In addition, they showed that when flow was occluded at either the cardiac inflow or outflow tracts, hearts with an abnormal third chamber, diminished looping and impaired valve formation ...