The purpose of the study is to determine whether the excretion of renal water- and salt-channels (Aquaporin-2 and Epithelial Sodium Channels) in the urine accurately reflects the handling of water and salt in the distal tubules af the kidneys, and whether quantification of these channels in the urine is useful to monitor and/or predict the effects of pharmacologic or surgical treatment of Heart Failure and heart failure-related diseases (Aortic stenosis, acute and chronic ischemic heart disease or pulmonary hypertension)