The purpose of the study is to examine the Vivio System's ability to track heart failure status in subjects, and compare the Vivio System's measurements to CardioMEMS measurements. Heart failure, which is a form of heart disease, is a condition where the heart does not pump enough blood through the body, resulting in the body not getting the amount of oxygen and nutrients it needs. This research study will collect data using CardioMEMS and the Vivio System in subjects over the age of 21 with a currently implanted, or scheduled to be implanted, CardioMEMS device. This group of individuals will provide researchers with important data because the measurements of their health information can be used to determine if the Vivio is as effective at tracking heart failure status as CardioMEMS. This research study is designed to develop new knowledge, and does not provide a direct benefit to study subjects