title: Diagnosis of secondary source of right-to-left shunt with balloon occlusion of patent foramen ovale and power M-mode transcranial Doppler.
abstract: OBJECTIVE
  We sought to assess the prevalence of secondary right-to-left circulatory shunt (RLS) in patients undergoing transcatheter closure of patent foramen ovale (PFO) as detected by power M-mode transcranial Doppler (TCD) and intracardiac echocardiography.
  
  
  BACKGROUND
  Prevalence of residual RLS in late follow-up after PFO closure may be as high as 34%. Other cardiac and noncardiac sources of RLS may coexist and obscure PFO closure evaluation.
  
  
  METHODS
  Eighty-eight patients who underwent transcatheter PFO closure to prevent recurrent paradoxical cerebral embolism between June 2005 and December 2006 were evaluated for a secondary source of RLS. Before device deployment, a sizing balloon was inflated in the PFO tunnel and agitated saline contrast was injected into the inferior vena cava. Clinically significant secondary RLS was defined as >10 embolic tracks on TCD at rest or immediately after calibrated (40 mm Hg), sustained (10 s) respiratory strain, with corresponding negative color-flow Doppler. Late residual RLS was evaluated in all patients with TCD and transthoracic echocardiography (mean: 192 days; 95% confidence interval [CI]: 161 to 223 days).
  
  
  RESULTS
  The sample (n = 84) was 59% female, age 49 +/- 14 years. Seventeen patients (20%; 95% CI: 11.7 to 28.8) had secondary RLS during balloon occlusion. At late follow-up (n = 66), 13 of 14 (93%) patients with secondary RLS and 23 of 52 (44%) patients without secondary RLS had residual RLS (p = 0.002).
  
  
  CONCLUSIONS
  This is the first report to systematically assess the prevalence of secondary RLS in patients undergoing PFO closure. Residual RLS detected by TCD may be due to secondary RLS, which may have implications for clinical outcomes.
authors.affiliation: Swedish Heart and Vascular Institute, Swedish Medical Center, Seattle, WA 98122, USA. jill.jesurum@swedish.org
authors.forename: Jill T
authors.initials: JT
authors.lastname: Jesurum
authors.forename: Cindy J
authors.initials: CJ
authors.lastname: Fuller
authors.forename: Joshua
authors.initials: J
authors.lastname: Renz
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Krabill
authors.forename: Merrill P
authors.initials: MP
authors.lastname: Spencer
authors.forename: Mark
authors.initials: M
authors.lastname: Reisman
mesh_terms: D000328:Adult; D021721:Balloon Occlusion / Q000295:instrumentation; D001775:Blood Circulation; D003287:Contrast Media / Q000008:administration & dosage; D019320:Embolism, Paradoxical / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D005260:Female; D054092:Foramen Ovale, Patent / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy; D006801:Humans; D007275:Injections, Intravenous; D020766:Intracranial Embolism / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011446:Prospective Studies; D055502:Secondary Prevention; D013997:Time Factors; D016896:Treatment Outcome; D018615:Ultrasonography, Doppler, Color; D017585:Ultrasonography, Doppler, Transcranial; D014682:Vena Cava, Inferior
chemical_list: D003287:Contrast Media