Hola Cesar,
The ADS1198 and ADS1298 are integrated devices that are used both for monitoring and diagnostic applications. One example of such products is the ViSi mobile patient monitoring system by Sotera Wireless (http://www.visimobile.com/).
These products would work in other applications as well, but the features they contain (Right Leg Drive, Lead-off Detection, and Respiration Measurement) are why they are particularly useful for simplifying ECG application designs.
Saludos,