Inclusion Criteria:  • Written informed consent  Male or female ≥18 years of age Meet ESC criteria for diagnosis of HF(4) Inpatient with a primary diagnosis of HF requiring treatment with intravenous furosemide at dose  Exclusion Criteria:  • Unable to consent to inclusion in study due to lack of capacity  Requiring treatment with intravenous furosemide at dose >200 mg per day as determined by the usual care team Current inotropes, vasopressors or intra-aortic balloon pump therapy Concomitant use of diuretics in 12 hours preceding administration of study drug with SQIN-Infusor Systolic blood pressure (SBP) <90 mmHg Pregnancy or breastfeeding Left sided valve disease with planned surgery or percutaneous intervention Type 1 myocardial infarction during index hospitalisation (type 2 myocardial infarctions are allowed)(5) Any surgical or medical condition which prevents patient from ambulation during the infusion Renal impairment, defined as eGFR < 30 mL/min/1.73 m2 at screening. Patient on active cardiac transplant waiting list Potassium <3.0 mmol/L Potassium >6.0 mmol/L Sodium <125 mmol/L Any contraindications for furosemide administration as per furosemide SmPC Any surgical or medical conditions, which in the opinion of the investigator may pose an undue risk to the subject, interfere with participation in the study or which may affect the integrity of the data