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:

1. Provision of signed and dated informed consent form

2. Male or female aged 18-35

3. History of preterm birth (either a or b):

1. Participant in the Newborn Lung Project (birth year 1988-1991, birth weight <1500
g)

2. Non-NLP participant, with birth weight <1500 g and gestational age 32 weeks or
less, verified by medical records

Exclusion Criteria:

1. Pregnant or lactating

2. Use of prescribed medications that would interfere with study medications

1. Sildenafil: Use of phosphodiesterase type 5 inhibitors (sildenafil, tadalafil,
vardenafil), nitrates, soluble guanylate cyclase inhibitor (riociguat) within 48
hours of study visit

2. Metoprolol: Use of nodal blocking agents including beta blockers,
non-dihydropyridine calcium channel blockers (i.e. diltiazem), and
anti-arrhythmics (i.e. amiodarone)

3. Presence of known comorbidities for which these therapeutic interventions would be
contraindicated:

1. Moderate to severe heart failure

2. Severe bradycardia (heart rate <45), or second or third-degree heart block

3. Systolic blood pressure <90 mmHg or >190 mmHg

4. Angina

5. Severe peripheral arterial circulatory disorders

6. History of severe bronchospasm

4. Presence of any implanted device incompatible with CMR imaging

5. Known allergic or hypersensitivity reaction to components of the study medications

6. Any other reason for which the investigator deems a subject unsafe or inappropriate
for study participation.