title: Determination of the optimum number of cardiac cycles to differentiate intra-pulmonary shunt and patent foramen ovale by saline contrast two- and three-dimensional echocardiography.
abstract: BACKGROUND
  Patent foramen ovale (PFO) and intra-pulmonary shunt (IPS) are potential causes of stroke. The most optimum cardiac cycle cutoff for bubbles to appear in the left heart on saline contrast transthoracic echocardiography (TTE) as criteria to differentiate the 2 entities is unknown.
  
  
  METHODS
  Ninety-five adult patients had saline contrast transesophageal echocardiography (TEE), two-dimensional (2D) and 3DTTE. Sensitivity and specificity of each cardiac cycle as cutoff to differentiate a PFO and IPS were obtained.
  
  
  RESULTS
  Transesophageal echocardiography showed IPS in 28 and PFO in 15 patients. If bubbles appeared in the left heart within the first 4 cardiac cycles (the 4th cardiac cycle rule) as compared to alternate cutoffs, a PFO was most accurately diagnosed by both 2D and 3DTTE. Bubbles appearing at or after the 5th cardiac cycle most accurately determined an IPS. 3D versus 2DTTE had a trend for a higher sensitivity (61% vs. 36%, P = 0.06), but similar specificity (94% vs. 91%) for IPS. Accuracy of 3DTTE was 84% and 2DTTE was 75% (P = 0.08) for IPS. For PFO, 2DTTE sensitivity (87%) and specificity (98%) did not differ (P = NS) from that of 3DTTE sensitivity (73%) and specificity (100%).
  
  
  CONCLUSIONS
  This study demonstrates for the first time that the 4th cardiac cycle rule differentiates PFO and IPS most optimally by 2D and 3DTTE. 3DTTE appears to have higher sensitivity for diagnosing IPS. These data suggest that 3DTTE is preferable when IPS is to be diagnosed. Both methods are similar for diagnosing PFO.
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, University of Louisville, Louisville, Kentucky.
authors.forename: Nirmanmoh
authors.initials: N
authors.lastname: Bhatia
authors.forename: Mohannad Y
authors.initials: MY
authors.lastname: Abushora
authors.forename: Macarius M
authors.initials: MM
authors.lastname: Donneyong
authors.forename: Marcus F
authors.initials: MF
authors.lastname: Stoddard
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003287:Contrast Media; D004452:Echocardiography / Q000379:methods; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D017548:Echocardiography, Transesophageal / Q000379:methods*; D005260:Female; D054092:Foramen Ovale, Patent / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006344:Heart Septal Defects, Atrial / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012965:Sodium Chloride; D020521:Stroke / Q000000981:diagnostic imaging / Q000503:physiopathology; D013318:Stroke Volume / Q000502:physiology; D055815:Young Adult
chemical_list: D003287:Contrast Media; D012965:Sodium Chloride
keywords: intra-pulmonary shunt; patent foramen ovale; three-dimensional echocardiography; transesophageal echocardiography