NCT02436213

Cardiopulmonary Exercise Testing to Evaluate Pulmonary AVMs

Hypoxemia, Dyspnea, and Exercise Tolerance in Patients With Pulmonary Arteriovenous Malformations

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 39 (actual)
• Sponsor: Imperial College London · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Accepted

Summary

Pulmonary arteriovenous malformations (PAVMs) are a rare vascular condition affecting the lungs. PAVMs lead to low blood oxygen levels, yet are very well tolerated by patients. This study will examine the exercise capacity of PAVM patients using formal cardiopulmonary exercise tests performed on a stationary bicycle.

Detailed description

It is well known that the lung is the site at which oxygen enters the blood stream, diffusing from the alveolar air sacs into the pulmonary capillaries. This newly oxygenated blood is carried to the heart in the pulmonary veins, then passes into the systemic circulation to provide oxygen to the tissues. Patients with pulmonary arteriovenous malformations (PAVMs) have abnormal vascular connections between pulmonary arteries and pulmonary veins in the lung. Blood flowing through PAVMs therefore bypasses the oxygenation sites in the pulmonary capillaries. Low blood oxygen levels (hypoxemia) is frequent in PAVM patients but breathlessness (dyspnea) is not. The investigators have shown that dyspnea was not a common presenting complaint in a large UK series, and that there is little correlation between severity of dyspnea in PAVM patients, and blood oxygen levels. In this study the investigators will address the question "Why are hypoxemic PAVM patients not more dyspneic?" The investigators will address this by first performing standardised cardiopulmonary exercise testing, as used in the clinic, on age and sex matched patients with PAVMs and healthy controls. Physiological parameters will be compared, to test the null hypothesis that the impact of exercise on PAVM patients' cardiopulmonary systems does not differ to normal controls. If the expected differences are confirmed, the investigators will examine if there is any difference to normals by re-examining the exercise tolerance of the PAVM cohort after they have had their PAVMs treated by embolization. Most patients with PAVMs have an underlying hereditary vascular disorder, hereditary haemorrhagic telangiectasia. Assuming the expected differences between PAVM patients and controls are confirmed, the investigators will therefore also examine which pattern HHT patients without PAVMs display. Finally, cellular and molecular methods will be used to dissect mechanistic pathways.

Conditions

• Pulmonary Arteriovenous Malformations
• Hereditary Hemorrhagic Telangiectasia

Interventions

Type	Name	Description
OTHER	Cardiopulmonary exercise test	On Day 1, subjects will have the test in the Exercise Suite of Hammersmith Hospital, London, UK. They will have painless skin probes placed on their fingers, chest, and legs to monitor heart rate, ECG, blood oxygen levels, and oxygen delivery during the test. Subjects will also be shown how to breathe through a mouthpiece with a nose clip on, and how to indicate on a sliding device whether they feel breathless. They will then start cycling against a very low resistance at a steady speed. As long as they feel comfortable, there will be a gradual increase in work load until they feel they cannot keep going at the same speed. They can also stop sooner for any reason. Afterwards, while they are "cooling down" (within the hour on Day 1), they will fill in a short questionnaire describing how they feel.
PROCEDURE	Blood test	On same day (Day 1), the subject will have 20-30mls of blood (that is, 4-6 teaspoonful) taken for analysis.

Timeline

• Start date: 2011-04-01
• Primary completion: 2015-03-01
• Completion: 2015-03-01
• First posted: 2015-05-06
• Last updated: 2023-09-28

Locations

1 site across 1 country: United Kingdom