The study is a randomized, placebo controlled, multi-center, single dose study to evaluate cardiac hemodynamics and safety of iv SLV320 in 110 subjects with congestive heart failure requiring diuretic treatment. Each subject will receive one dose of SLV320 or placebo or furosemide. The study consists of three visits (or study days when in-subjects are included). Ambulatory subjects will be in hospital for two nights and one day.