title: Unilateral versus bilateral middle cerebral artery detection of right-to-left shunt by power M-mode transcranial doppler.
abstract: OBJECTIVE
  Comparison was performed between unilateral and bilateral power M-mode transcranial Doppler to detect right-to-left circulatory shunt (RLS).
  
  
  METHODS
  Recorded Doppler data from 87 patients with confirmed RLS referred for transcatheter closure of patent foramen ovale were reanalyzed for embolic tracks (ET) counted from left and right temporal bone windows during bubble study. Unilateral counts were obtained by multiplying each side by 2; bilateral counts were obtained by summing left and right ET. Both unilateral and bilateral ET were converted to a 6-point logarithmic grade. Sex and age group subanalyses were performed.
  
  
  RESULTS
  At rest, significantly more ET were detected with bilateral versus unilateral detection (P= .01), but not following Valsalva (P= .13). Unilateral and bilateral detection were equally able to detect large RLS (grades IV or V) following Valsalva (P= 1.00). For the group aged > or =55 years, the right-hand side yielded greater ET than the left-hand side (mean difference 9%+/- 37; 95% confidence interval -3 to 21%) at rest (P= .01), but not following Valsalva (mean difference 1%+/- 25; 95% confidence interval -7 to 9%, P= .10).
  
  
  CONCLUSIONS
  Unilateral detection of ET by power M-mode transcranial Doppler is equivalent to bilateral detection to assess RLS.
authors.affiliation: Department of Cardiovascular Scientific Development, Swedish Medical Center, Seattle, Washington 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: Mark A
authors.initials: MA
authors.lastname: Moehring
authors.forename: Joshua
authors.initials: J
authors.lastname: Renz
authors.forename: Meryl
authors.initials: M
authors.lastname: Harley
authors.forename: Merrill P
authors.initials: MP
authors.lastname: Spencer
mesh_terms: D000367:Age Factors; D002539:Cerebral Arterial Diseases / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012737:Sex Factors; D013701:Temporal Bone; D017585:Ultrasonography, Doppler, Transcranial