Inclusion Criteria:

• Healthy Young Volunteers: 18-30 years of age with no diseases or conditions that would affect their participation in the study
• Healthy Older Controls: volunteers 65 years of age or older with no diseases or conditions that would affect their participation in the study
• Coronary Angiography subjects: patients undergoing routine coronary angiography
• Chronic Obstructive Pulmonary Disease subjects: patients diagnosed with mild to moderate COPD
• Pulmonary Arterial Hypertension subjects: patients with idiopathic or heritable Group 1 pulmonary arterial hypertension
• Heart Failure subjects: patients with Class I, II or III New York Heart Association symptoms of Heart Failure
• Hypertension subjects: patients diagnosed with chronic high blood pressure

Exclusion Criteria:

• Severe COPD (use of supplemental oxygen, or have a one-second forced expiratory volume of less than 30% predicted)
• History of myocardial infarction
• History of percutaneous coronary revascularization
• History of coronary artery bypass grafting
• Unstable angina pectoris
• History of variant angina
• Ejection fraction < 50%
• Significant renal disease (Glomerular Filtration Rate < 50 mL/min/1.73m2)
• Subjects whose medical care or safety may be at risk from undergoing a Magnetic Resonance Imaging examination (e.g. pacemaker, metal implants, certain types of heart valves)
• Subject is pregnant
• Subject has physical ailments (other than COPD, PAH, HF, or hypertension) that would prevent them from study participation in the judgment of the investigator