Does a patent foramen ovale influence cognitive function in dialysis patients?

Background: Patients with chronic kidney disease on dialysis treatment have poorer cognitive function than age- and sex-matched controls. One proposed mechanism is cerebral microembolisation due to material from the dialysis circuit crossing a patent foramen ovale (PFO).

Methods: Cognitive testing was carried out in haemodialysis (HD) patients and peritoneal dialysis (PD) patients. Transthoracic echocardiography was used to identify PFO. Follow-up testing 1 year later enabled comparison of cognitive decline between patients with and without a PFO, and between those undergoing different dialysis modalities.

Results: 80 patients (aged 60.4 ± 15.0 years) were recruited (51 HD patients and 29 PD controls). A PFO was found in 21% of patients. 83% of dialysis patients suffered a decline in one or more cognitive function tests over 1 year. There was a significant difference in only one test between HD patients with or without a PFO. PD patients showed a more rapid cognitive decline than those on HD.

Conclusions: Cognitive decline in dialysis patients is rapid and affects most patients. The presence of a PFO made only subtle differences to the rates of cognitive decline during 1 year of follow-up. Patients with a PFO should not be prevented from considering HD because of concerns of cerebral decline due to microembolisation.