Evaluating the Effects of Nitroglycerin on Heart Function and Urinary Output in Patients With Acute Heart Failure

Inclusion Criteria: * Age ≥ 18 years * Clinical diagnosis of AHF requiring hospitalization * Systolic blood pressure ≥85 mmHg * Echocardiographic signs of cardiac dysfunction, by at least one of * Left ventricular ejection fraction ≤45% * Abnormal left ventricular filling with dilatation of the left atrium * Elevated filling pressures (systolic pulmonary artery pressure\>30, dilated vena cava inferior or E/é\>10) * Significant left-sided heart valve disease Exclusion Criteria: * Ongoing ventricular taky- or brady-arrythmias or supraventricular arrhythmias with heart rate \> 180 or \< 40 bpm. * Retinopathy or intraocular lens implantation (contraindication to Valsalva maneuver) * Recent myocardial infarction or thromboembolic events. * Intake of sildenafil or vardenafil withing 24 h and tadalafil within 48 h. * Absolute contraindication for vasodilation using nitroglycerin as assessed by treating physician * Intravenous administration of furosemide within 2 hours of baseline measurements