Citrix Presentation Server 4.5 introduced a new feature called Health Assistant for Enterprise and Platinum editions. This feature maintains the health of critical services in a Presentation Server farm.
Every Presentation Server has a service called a Health Check Agent (HCA) that periodically runs the tests to review the health of that server. If a test fails, the system can take a pre-configured corrective action along with writing to the event log.
PS 4.5 comes with 4 health tests and now, 6 new tests have been released.