For many new medical research questions in heart surgery comprehensive and large data bases are essential. We discuss typical challenges for the integration of real-time and legacy data stored in multiple unconnected hospital information systems (HIS). Furthermore the HIS are often operated by autonomous departments whose data base structures are subject to occasional modifications.

We present a solution which integrates and consolidates all research relevant data in a data mart without imposing any considerable operational or maintenance contract liability risk for the existing HIS. The problems of partial consistency and partial redundancy in the data are discussed.

The data mart system serves multiple purposes: beside clinical reporting and quality assessment, the preparation steps for comprehensive studies are enormously simplified.