The main purpose of the Phase II research will be to validate clinical applicability of MPEG-2 compression to digital echocardiography on a representative sample through a multi-center clinical trial. Each participating institution will collect 60 carefully selected digital cases from patients with non-echocardiographically verified abnormalities. All trial studies will be transferred via a wide area network to a remote trial repository via the Internet. Readers will access the Repository via Internet and will read and intepret all studies on-line. The Repository will comprise of a secure database system for digital video, text and form management and with a statistics database. Free Response Receiver Operator Characteristics parameters will be calculated automatically in a """"""""near real time"""""""" fashion from on-line reader entries. Three hypotheses will be tested in Phase II: 1] MPEG2 compression is diagnostically equivalent to non-compressed echocardiography data, 2] MPEG2 compressed digital echocardiographic studies are esthetically (perceived image quality) equivalent to images commonly encountered in current echocardiography practice, 3] MPEG2 compressed digital echocardiography is easy to read and increases the efficiency of an echocardiographic laboratory and lowers its operating costs. Proposed infrastructure will utilize standard DICOM 3.0 record format and secure Internet TCP/IP network for image delivery. Phase II research is a logical next step in development and deployment of practical CPACS software product for the marketplace in Phase III.