Few research groups are studying the biomechanical aspects of cardiovascular development. The pioneering work on physiology was initiated by Clark and colleagues over the last 25 years. The SCOR research team has expanded to include pediatric cardiologists, biologists, experimental and theoretical biomechanics. The information on the functional and material characteristics of the heart are integral to the analysis of genetic and cell manipulation of the developing cardiovascular system. The work of Dr. Tsyvian and colleagues has focused on the active material properties of myocardium. These research techniques are important additional measures of the developing heart. Thus this FIRCA is conceived as a natural extension of ongoing research programs supported under the SCOR mechanism. Dr. Tsyvian will provide immediate access to active material properties testing that would require extensive development at the University of Rochester. In return, Dr. Tsyvian will become part of a large integrated research group with close ties to the community of investigators in the molecular and cell biology of the developing cardiovascular system. Dr. Tsyvian was chosen because of his prior research experience, unique experimental tools, and prior experience in western laboratories. Dr. Tsyvian has been a visiting scientist at the Erasmus University Rotterdam, The Netherlands, one of the sites for performance of the SCOR. His credible investigation with Professor Wladimiroff assures successful completion of the Proposed research program of this FIRCA. Thus, this proposal will expand the network of scientists investigating the basic biomechanics of the developing heart, providing insight into the formation of the myocardium and developing basic understanding of mechanisms that are likely integral to the broad range of human myocardial disease.