Cardiovascular Responses in Congestive Heart Failure With Cheyne- Stokes Respiration

Inclusion Criteria: * Moderate to severe heart failure (NYHA Class II or above) on optimal medical therapy * LVEF less than or equal to 45% * Stable condition as defined as no hospital admission or changes to medical therapy within two weeks prior to enrolment Exclusion Criteria: * Patients taking known respiratory stimulants or depressants * Clinically significant asthma requiring therapy * Significant parenchymal lung disease * Primary pulmonary hypertension * Myocardial infarction within three months prior to enrolment * Patients with cardiac resynchronisation devices and permanent pacemakers * Anaemic (haemoglobin \< 12g/dL)