A Crossover Study of Patients With HF to Compare Natriuretic Effects of IR Torsemide vs. ER Torsemide Over 12 Hrs

The goal of this randomized double-blind crossover study is to assess whether extended release torsemide has a better efficacy than immediate release torsemide to induce renal sodium excretion after a salty lunch in patients with heart failure. The study will address if: * the amounts of excreted sodium in the urine during the 2- and 6-hours' time period after a morning dose of extended release torsemide is different from the amounts after the immediate release torsemide. * the amounts of excreted sodium in the urine during the 2- and 6-hours' time period after a salty lunch, which will be consumed approximately 6 hours following a morning dose of extended release torsemide, is different from the amounts after the immediate release torsemide. * the amount of excreted sodium in the urine during the 24 hours' time period after a salty lunch, which will be consumed approximately 6 hours following a morning dose of extended release torsemide, is different from the amount after the immediate release torsemide.