Improving Right Ventricular Function in Young Adults Born Preterm

The purpose of this study is to evaluate the short-term therapeutic effects of sildenafil and metoprolol on right ventricular function in young adults born premature using novel 4-Dimensional flow Cardiac Magnetic Resonance Imaging.

Inclusion criteria

• Provision of signed and dated informed consent form
• Male or female aged 18-35
• History of preterm birth (either a or b):

• Participant in the Newborn Lung Project (birth year 1988-1991, birth weight <1500 g)
• Non-NLP participant, with birth weight <1500 g and gestational age 32 weeks or less, verified by medical records

Exclusion criteria

• Pregnant or lactating
• Use of prescribed medications that would interfere with study medications

• Sildenafil: Use of phosphodiesterase type 5 inhibitors (sildenafil, tadalafil, vardenafil), nitrates, soluble guanylate cyclase inhibitor (riociguat) within 48 hours of study visit
• Metoprolol: Use of nodal blocking agents including beta blockers, non-dihydropyridine calcium channel blockers (i.e. diltiazem), and anti-arrhythmics (i.e. amiodarone)
• Presence of known comorbidities for which these therapeutic interventions would be contraindicated:

• Moderate to severe heart failure
• Severe bradycardia (heart rate <45), or second or third-degree heart block
• Systolic blood pressure <90 mmHg or >190 mmHg
• Angina
• Severe peripheral arterial circulatory disorders
• History of severe bronchospasm
• Presence of any implanted device incompatible with CMR imaging
• Known allergic or hypersensitivity reaction to components of the study medications
• Any other reason for which the investigator deems a subject unsafe or inappropriate for study participation.