Effect of mechanIcal circulatoRy Support ON Exercise Capacity aMong pAtieNts With Heart Failure

Advanced Heart Failure- Inclusion Criteria: * Individuals with severely reduced left ventricular systolic function that are scheduled to undergo LVAD insertion Exclusion Criteria: * uncontrolled diabetes with peripheral neuropathy (interferes with acquisition of MSNA signal) * Individuals with clinical right ventricular failure, defined as moderate-severely reduced RV systolic function on echocardiography, or clinical evidence of RV failure (elevated jugular venous pressures, significant peripheral edema) * Individuals with moderate-severe preexisting aortic insufficiency, as these patients will typically undergo a Park stitch at time of CF-LVAD insertion to permanently close the aortic valve and prevent worsening aortic insufficiency; and * Disorders that adversely influence exercise ability (e.g. arthritis, peripheral vascular disease, pulmonary disease) Mild Heart Failure - Inclusion Criteria: * Individuals with medically managed left ventricular systolic function that are NOT scheduled to undergo LVAD insertion * HF patients with ejection fraction \<35-40% Exclusion Criteria: * Individuals requiring systemic anticoagulation with vitamin-K antagonists or new/direct oral anticoagulants ("NOAC"/"DOAC") * Disorders that adversely influence exercise ability (e.g. arthritis, peripheral vascular disease, pulmonary disease) * History of uncontrolled arrhythmias (e.g. ventricular tachycardia or nonsustained ventricular tachycardia). Healthy Controls - Inclusion Criteria: \- Persons without a past medical history of cardiovascular disease or related disease (e.g. hypertension, diabetes, peripheral vascular disease, arrhythmias, stroke/transient ischemic attack) and are not taking any cardiac-related medications (e.g. antihypertensive medications) Exclusion Criteria: * Individuals requiring systemic anticoagulation with vitamin-K antagonists or new/direct oral anticoagulants ("NOAC"/"DOAC") * Disorders that adversely influence exercise ability (e.g. arthritis, peripheral ascular disease).