A biomedical engineer sees the heart as a pump, plain and simple, a machine shaped by genetics and complex biomechanical forces.Larry A. Taber, professor of biomedical engineering at Washington University in St. Louis, has been probing the forces, stresses and deformations of the heart since the mid-1980s. A major focus of his work is to show that biomechanical forces may be as important as genetics in shaping the heart.
Recently, he has developed a theory on tissue growth and morphogenesis (shape change) and applied it to understanding the developing heart in chicken embryos, which is remarkably similar to its counter-part in human. Taber is studying looping one of the most critical stages of embryo heart development, where the heart at just two days of age in chickens (three weeks in humans) bends outward and rotates to the right.This must happen perfectly to avoid misconnections of arteries in the herat walls and holes in the heart, among other serious developmental problems. His research could help scientists better understant the roles physics and mechanics play in the developing heart and in heart defects. The heart either loops or it doesn’t, and if it loops it either goes left or right,’ and those often are the only distinctions made.
It takes 21 days to hatch a chicken; at day 1 tubes form on two sides of the embryo and come together to form one tube. At this juncture (two-and-a-half weeks in the human embryo) the heart is just starting to beat. During the second day, blood flow starts and by the third day the tube is beginning to look like a heart, with septums later forming in two different regions to create left and right ventricles on one side, and right and left atria on the other, says Taber.
It appears that regional stiffness plays a role in bending. Taber collaborator, Dimitri Vornov, a visiting scientist at Washington University, has discovered that a membrane that covers the tube may play a major role in causing the rotation to the right.Taber says engineers are just now looking at growth in mature heart. His theory will be valuable in looking at these situations. Growth occurring in the mature heart is extremely important and plays a role in adaptation to high blood pressure (thicker heart walls) and heart attack.
