Researchers from the National Heart and Lung Institute at Imperial College, London, looked at how the lungs become inflamed in COPD sufferers.

BBC: NEWS | Health | Red wine 'may treat lung disease'

But Professor Peter Sever, of the National Heart and Lung Institute at Imperial College London, said there were already effective drugs for heart failure and that Viagra's action was not unique.

BBC: NEWS | Health | Viagra could treat failing hearts