Veterans’ Health Information Systems and Technology Architecture (VistA). It is an enterprise-wide information system built around an Electronic Health Record (EHR). It is used throughout the United States Department of Veterans Affairs (VA) medical system, known as the Veterans Health Administration (VHA). It consists of nearly 160 integrated software modules for clinical care, financial functions, and infrastructure.
The VHA manages the largest medical system in the States providing care to over 8 million veterans, employing 180,000 medical personnel and operating 163 hospitals & 800 clinics,135 nursing homes throughout the continental U.S., Alaska and Hawaii on a single electronic healthcare information network. Nearly 25% of the nation's population is potentially eligible for VA benefits and services because they are veterans, family members, or survivors of veterans.
vista modules &    projects
VistA was developed using MUMPS database. The VA currently runs a majority of VistA systems on the proprietary InterSystems Caché version of MUMPS, but an open source MUMPS database engine, called GT.M, for Linux and Unix computers has also been developed. VistA is now bundled with the GT.M database in an integrated package. The free, open source nature of GT.M allows redundant and cost-effective failsafe database implementations, increasing reliability for complex installations of VistA.
An open source project called Esi Objects has allowed the (ANSI- Standard) MUMPS database technology to evolve into a modern object-oriented language that can be integrated into state-of-the-art technologies. M2Web is an open source web gateway to MUMPS for use with VistA. A free open source module from M/Gateway called MGWSI has been developed to act as a gateway between GT.M, Cache, or M21 MUMPS databases and programming tools such as PHP or Java, in order to create a web-based interface.
PAITENT WEB PORTAL
Patient portals are healthcare-related online applications that allow patients to interact and communicate with their healthcare providers. Some patient portal applications exist as stand-alone web sites and sell their services to healthcare providers. MyHealtheVet is a web portal that allows veterans to access and update their personal health record, refill prescriptions, and schedule appointments. This also allows veterans to port their health records to institutions outside the VA health system or keep a Personal Health Records (PHR). .
The Veterans Administration has also developed VistA Imaging, a coordinated system for communicating with PACS and for integrating others types of image-based information into the VistA electronic medical records system. . VistA Imaging has been made freely available in the public domain for private/public hospital use through the Freedom of Information Act. (Licensing of several proprietary modules are required for it to function correctly. It can be used independently or integrated into the VistA electronic health record system.