Screening for pulmonary arteriovenous malformations: contrast echocardiography versus pulse oximetry

Pulmonary arteriovenous malformations (PAVM) cause right-to-left shunt and imply risk of paradoxical embolism and cerebral abscess. These complications can be prevented by appropriate treatment. Detection of PAVMs is therefore important, so simple and reliable screening methods are needed for this purpose. The aim of this investigation was to compare pulse oximetry and contrast echocardiography as screening tools for detection of pulmonary arteriovenous malformations. Eighty-five hereditary haemorrhagic telangiectasia (HHT) patients and first-degree relatives identified in a comprehensive study of HHT-families in the county of Funen, Denmark, were investigated. Standing and supine pulse oximetry in room air was performed in all subjects, and in subjects with symptoms and/or abnormal pulse oximetry in room air, supine pulse oximetry breathing 100% oxygen was also performed. Transthoracic echocardiography with intravenous injection of echo contrast was performed in all subjects. Outcome measures were oxygen saturation change >2% units on changing body position and echo contrast observed in the left-sided heart chambers. Positive contrast echocardiography indicating the presence of PAVM was found in 47 subjects, whereas pulse oximetry was abnormal in only 16. The results strongly suggest that contrast echocardiography is a more sensitive screening tool for PAVMs than pulse oximetry.