title: Is the search for right-to-left shunt still worthwhile?
abstract: OBJECTIVE
  Patent foramen ovale (PFO) is a common disembryogenic defect with well-attested prevalence but dubious etiopathogenetic linkage with cryptogenic stroke and different clinical conditions. Transcranial color-coded Doppler (TCCD) assures high accuracy in diagnosing right-to-left shunt (RLS) and its functional aspects. Aim of the study was to evaluate RLS prevalence and degree in subjects submitted to TCCD for conditions theoretically associated or caused by paradoxical embolism to the brain.
  
  
  METHODS
  PFO assessment, performed in 10 major diagnostic categories and a control group, followed a standardized protocol with a 10 or 20 microbubbles (MB) cutoff to identify any or only large RLS, respectively.
  
  
  RESULTS
  Among 2113 patients, a significant larger RLS prevalence was found in stroke (53.3%), TIA (45.7%) and migraine with aura (39.7%) when compared with non-migraineurs controls (25.5%). RLS degree was significantly higher in stroke and TIA patients: The ROC curve from MB load data helped to identify new cutoff values for both normal breathing (42 MB) and Valsalva (139 MB) tests. From logistic regression, a family history for PFO, ASA, and male gender appeared independent predictors of a RLS. By contrast, RLS seemed independent of white matter abnormalities presence on brain neuroimaging or stroke mimics.
  
  
  CONCLUSIONS
  In addition to recently defined criteria, genetically determined inheritable traits and epidemiologic characteristics (male gender) should be taken into account when assessing PFO and related cerebrovascular risk profile. A newly defined threshold in TCCD MB count is suggested to discriminate shunts related to stroke and TIA from innocent ones.
authors.affiliation: Service of Neurology, Piccole Figlie Hospital, Parma, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Tanzi
authors.affiliation: Cardiovascular Department, Humanitas Gavazzeni Hospital, Bergamo, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Onorato
authors.affiliation: Interventional Cardiology Unit, IRCCS Policlinico San Donato, Milano, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Casilli
authors.affiliation: Service of Neurology, Piccole Figlie Hospital, Parma, Italy.|Neurosonology Clinic, Fondazione Poliambulanza, Brescia, Italy.|Neurology Clinic and Rehabilitation Department, Casa di Cura Villa Barbarano, Salò, Italy.
authors.forename: G P
authors.initials: GP
authors.lastname: Anzola
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D054092:Foramen Ovale, Patent / Q000000981:diagnostic imaging / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D020521:Stroke / Q000000981:diagnostic imaging / Q000453:epidemiology*; D017585:Ultrasonography, Doppler, Transcranial
keywords: microbubble count; migraine; patent foramen ovale; shunt; stroke; transcranial Doppler