According to Doug Cowan the muscle cells designed to encourage the growth of stem cells may one day replace pacemakers in children and keep young hearts beating on time. Doug Cowan is an assistant professor of anesthesia at Children's Hospital Boston. The synchronized ta-dum of a healthy heartbeat is created by electrical impulses which move first through the atria that contracts, then, after a short pause, to the ventricles, which contracts thus forcing blood through the body. When this system fails because the electrical signals cannot pass through the heart, the rhythm is disturbed, at times fatally. The present treatment is to implant a pacemaker to reestablish the connection. But pacemakers don't last forever, and infants have to undergo several operations to implant new devices as they grow. Cowan's research is aimed at engineering stem cells which will develop into a conductive tissue for the heart and restrain the need for a pacemaker. Cowan's work is in its early stages, and a crucial question lingers as how to get the stem cells into a child's body. Cowan says delivery itself kills a lot of cells.