Clinical Trial: Cardiopulmonary Exercise Testing to Evaluate Pulmonary AVMs

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

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

Brief 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 Summary:

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. Ass
Sponsor: Imperial College London

Current Primary Outcome: Total body oxygen consumption in mls/min/kg, at peak exercise (VO2 max). [ Time Frame: Same day (Day 1), at end of exercise study ]

Of the many measurements and derived indices that can be measured during cardiopulmonary exercise testing, the peak consumption of oxygen (VO2 max) is perhaps the best indicator of integrated cardiorespiratory capacity. The principle research question will therefore test the null hypothesis that "The VO2 max does not differ between PAVM patients and age matched healthy controls."


Original Primary Outcome: Total body oxygen consumption in mls/min/kg, at peak exercise (VO2 max). [ Time Frame: Same day, at end of exercise study ]

Of the many measurements and derived indices that can be measured during cardiopulmonary exercise testing, the peak consumption of oxygen (VO2 max) is perhaps the best indicator of integrated cardiorespiratory capacity. The principle research question will therefore test the null hypothesis that "The VO2 max does not differ between PAVM patients and age matched healthy controls."


Current Secondary Outcome:

  • Breathing reserve (%) [ Time Frame: Same day (Day 1) at end of exercise test ]
    We will also test in univariate and multiple regression analyses whether breathing reserve differs between PAVM patients and controls.
  • Ventilatory efficiency, derived from the VE / CO2 slope (L/min/L/min) [ Time Frame: Same day (Day 1), at end of exercise study ]
    We will also test in univariate and multiple regression analyses whether ventilatory efficiency differs between PAVM patients and controls.


Original Secondary Outcome:

  • Breathing reserve [ Time Frame: Same day at end of exercise test ]
    We will also test in univariate and multiple regression analyses whether breathing reserve differs between PAVM patients and controls.
  • Ventilatory efficiency [ Time Frame: Same day, at end of exercise study ]
    We will also test in univariate and multiple regression analyses whether ventilatory efficiency differs between PAVM patients and controls.


Information By: Imperial College London

Dates:
Date Received: October 16, 2012
Date Started: April 2011
Date Completion: September 2017
Last Updated: October 21, 2015
Last Verified: October 2015