Heart hole worsens sleep apnoea

Sleep apnoea worsens in people with a relatively common heart defect called patent foramen ovale or PFO. In PFO, an opening between the heart's two upper chambers that normally closes during fetal development remains open. PFO is present in 25 percent of the adult population, and the defect may allow blood, low in oxygen, to pass through the hole in the heart. Most people with patent foramen ovale don't know they have the condition because patent foramen ovale usually doesn't cause any signs or symptoms. Most people with patent foramen ovale don't need treatment, although closing the opening with a device is an option. Obstructive sleep apnoea (OSA) is a condition in which a person experiences frequent, short periods of obstructive breathing during sleep. It affects up to 15 percent of middle-aged adults and produces varying degrees of low blood-oxygen levels (also called oxygen desaturation). Researchers from the Sahlgrenska University Hospital, Ostra, Sweden found that oxygen desaturation was more common, and occurred in proportion to the frequency of breathing disturbances, in patients with PFO. From a larger group of 209 diagnosed with OSA, the Swedish group identified 15 OSA patients with frequent desaturation, and matched them with 15 OSA patients with few episodes of desaturation. The 30 subjects were then screened for the presence of PFO. The presence of PFO was more common in patients with more episodes of desaturation than in those with fewer episodes of desaturation. Sixty percent of apnoea subjects with frequent episodes of desaturation had a large patent foramen ovale compared with just 13 percent of those with few desaturation episodes. The findings suggest that that shunting of blue blood (without oxygen) through the PFO contributes to low blood-oxygen levels in sleep apnoea subjects with this heart defect. Moreover, this could explain the increased risk of stroke seen in OSA. If this link could be established, closing the PFO using a catheter technique may be a potential treatment option in the future.