Safety and Efficacy of Direct Blood Volume Measurement in the Treatment of Heart Failure

Multicenter prospective randomized trial to compare heart failure management strategies based on clinical assessment of volume status vs. direct measurement of blood volume with a radioisotope technique. Subjects will be randomly assigned to a standard care strategy with guideline recommended treatment based on serial clinical assessment of blood volume or a measured blood volume strategy with guideline recommended treatment based on serial measured blood volume. All subjects will undergo blood volume measurement procedures, but the testing results will only be returned to the physician in the group assigned to management according to measured blood volume status. Subjects will be blinded to their study treatment assignment status.