0.5M Na Lactate Solution in Acute Heart Failure (AHF)

Inclusion Criteria: * Age: more than 18 years * Heart failure criteria: Left heart failure: as evidenced by 2 out of 3: * Left ventricular ejection fraction (LVEF) ≤ 40% and cardiac index ≤ 2.5 L/min/m2 * Acute pulmonary oedema of cardiac origin or mechanical ventilation (including CPAP/BIPAP) for respiratory failure of predominantly cardiac origin * Need for inotropes/vasopressors for cardiac pump failure OR Right heart failure: as evidenced by 1 out of 2: * Bilateral leg oedema above ankles * RV failure (low tricuspid annular plane systolic excursion (TAPSE), dilated floppy RV) * Poor peripheral perfusion as evidenced by 2 out of 3: Cold mottled skin Low urine output Acutely clouded sensorium/poor mentation * Consent obtained from patient or patient's next of kin. Exclusion Criteria: * Hypernatremia: \[Na\] \>145 mmol/L * Diagnosed hypertrophic obstructive cardiomyopathy * Uncorrected severe valvular heart disease * Documented third degree heart block, sustained ventricular tachycardia * Documented cardiac tamponade * Septic shock * Acute respiratory distress syndrome (ARDS) * Moribund patients likely to die before 24h * Patients with major diseases of limited prognosis such as end stage cancer,end-stage liver failure, end stage dialysis dependent renal failure * Patients with absolute indication for acute hemodialysis/hemofiltration (pH, K, urea \> 35 mmol/L, severe fluid overload in the presence of oliguria \< 200 mL/6h. * Known pregnancy