A 44-year-old woman was referred to our centre for interventional cardiac catheterisation. The diagnostic work-up after a preceding ischaemic stroke led to the assumption of a patent foramen ovale due to a positive bubble study. Before the planned percutaneous closure of the patent foramen ovale, we performed a second bubble study, which showed an intact atrial septum. However, after two to three heart cycles bubbles could be detected in the left atrium, assuming a right-to-left shunt of an extracardiac origin most likely in the lung. We therefore performed cardiac catheterisation, yielding a pulmonary arteriovenous malformation in the lower lobe of the right lung. This was successfully closed interventionally by placing a Cook coil, as well as several plugs into the malformation and feeding vessels.