title: Accuracy of transcranial Doppler for the diagnosis of intracardiac right-to-left shunt: a bivariate meta-analysis of prospective studies.
abstract: OBJECTIVE
  The aim of this meta-analysis was to determine the accuracy of transcranial Doppler (TCD) compared with transesophageal echocardiography (TEE) as the reference.
  
  
  BACKGROUND
  Right-to-left shunting (RLS), usually through a patent foramen ovale (PFO), has been associated with migraine, cryptogenic stroke, and hypoxemia. With emerging observational studies and clinical trials on the subject of PFO, there is a need for accurate diagnosis of PFO in patients with these conditions, and those being considered for transcatheter closure. Although a TEE bubble study is the current standard reference for diagnosing PFO, the TCD bubble study may be a preferable alternative test for RLS because of its high sensitivity and specificity, noninvasive nature, and low cost.
  
  
  METHODS
  A systematic review of Medline, the Cochrane Library, and Embase was done to look for all the prospective studies assessing intracardiac RLS using TCD compared with TEE as the reference; both tests were performed with a contrast agent and a maneuver to provoke RLS in all studies.
  
  
  RESULTS
  A total of 27 studies (29 comparisons) with 1,968 patients (mean age 47.8 ± 5.7 years; 51% male) fulfilled the inclusion criteria. The weighted mean sensitivity and specificity for TCD were 97% and 93%, respectively. Likewise, the positive and negative likelihood ratios were 13.51 and 0.04, respectively. When 10 microbubbles was used as the embolic cutoff for a positive TCD study, TCD produced a higher specificity compared with when 1 microbubble was used as the cutoff (p = 0.04); there was, however, no significant change in sensitivity (p = 0.29).
  
  
  CONCLUSIONS
  TCD is a reliable, noninvasive test with excellent diagnostic accuracies, making it a proficient test for detecting RLS. TCD can be used as a part of the stroke workup and for patients being considered for PFO closure. If knowledge of the precise anatomy is required, then TEE can be obtained before scheduling a patient for transcatheter PFO closure.
authors.affiliation: Division of Cardiology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York. Electronic address: mkmojadidi@gmail.com.
authors.forename: M Khalid
authors.initials: MK
authors.lastname: Mojadidi
authors.affiliation: Division of Cardiology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Roberts
authors.affiliation: Division of Cardiology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York.
authors.forename: Jared S
authors.initials: JS
authors.lastname: Winoker
authors.affiliation: Division of Cardiology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York.
authors.forename: Jorge
authors.initials: J
authors.lastname: Romero
authors.affiliation: Division of Cardiology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York.
authors.forename: David
authors.initials: D
authors.lastname: Goodman-Meza
authors.affiliation: Program in Interventional Cardiology, Division of Cardiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California.
authors.forename: Rubine
authors.initials: R
authors.lastname: Gevorgyan
authors.affiliation: Program in Interventional Cardiology, Division of Cardiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Tobis
mesh_terms: D000328:Adult; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging* / Q000209:etiology; D003287:Contrast Media; D017548:Echocardiography, Transesophageal; D005260:Female; D054092:Foramen Ovale, Patent / Q000150:complications / Q000000981:diagnostic imaging* / Q000628:therapy; D006801:Humans; D008297:Male; D045423:Microbubbles; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D003287:Contrast Media
keywords: patent foramen ovale; right-to-left shunt; transcranial Doppler