title: Time course of high-intensity transient signals in patients undergoing elective heart valve replacement: a prospective study.
abstract: OBJECTIVE
  This study was performed to evaluate the time course of intracranial high-intensity transient signals (HITS) in patients undergoing elective heart valve replacement.
  
  
  METHODS
  Thirty-three patients were enrolled in this study. The examination protocol included serial (before and at one, five, 90 and 180 days after surgery) monitoring sessions with transcranial Doppler and detailed neurological examination. Monitoring was performed bilaterally over the middle cerebral arteries for one hour per session using 2 MHz probes. Microembolic signals were recognized according to standard criteria and stored on a computer for later evaluation.
  
  
  RESULTS
  HITS prevalence increased from 3% preoperatively to 41% on the first postoperative day and remained unchanged during the postoperative period. No influence of the intensity of anticoagulation or valve type on HITS counts was evident. Unilateral monitoring provided adequate results in 83.9% of cases.
  
  
  CONCLUSIONS
  The causative role of the valve implant in the pathogenesis of HITS appears certain, since their prevalence dramatically increases following valve implantation. Valve type, duration of valve implant or intensity of anticoagulation did not influence HITS counts. Bilateral monitoring is warranted for accurate evaluation of HITS counts in this patient group.
authors.affiliation: Department of Neurology, Martin-Luther-University Halle-Wittenberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Lindner
authors.forename: D
authors.initials: D
authors.lastname: Georgiadis
authors.forename: A
authors.initials: A
authors.lastname: Lühmann
authors.forename: M
authors.initials: M
authors.lastname: Stephan
authors.forename: M
authors.initials: M
authors.lastname: Preiss
authors.forename: H R
authors.initials: HR
authors.lastname: Zerkowski
authors.forename: S
authors.initials: S
authors.lastname: Zierz
mesh_terms: D001021:Aortic Valve; D017558:Elective Surgical Procedures; D005260:Female; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve; D008991:Monitoring, Physiologic; D009460:Neurologic Examination; D011182:Postoperative Care; D011300:Preoperative Care; D015995:Prevalence; D011446:Prospective Studies; D017585:Ultrasonography, Doppler, Transcranial