title: Intracranial high-intensity transient signals after homograft or mechanical aortic valve replacement.
abstract: OBJECTIVE
  Comparison of the occurrence, intensity and rate of high-intensity transient signals (HITS), measured in both middle cerebral arteries by transcranial Doppler ultrasound (TCD) after mechanical or homograft aortic valve implantation.
  
  
  METHODS
  TCD monitoring was performed by means of a pulsed Doppler ultrasound with two 2 MHz probes, stabilized on the head and directed at the middle cerebral artery.
  
  
  METHODS
  Outdoor patients after aortic valve replacement in a university hospital.
  
  
  METHODS
  The study cohort comprised a random transverse sample of patients and included 20 patients with a mechanical aortic valve and 20 with a homograft aortic valve. Comparisons were made with 20 admitted control patients.
  
  
  METHODS
  No interventions.
  
  
  METHODS
  No significant number of HITS were expected in the homograft group and a limited number in the mechanical valve group.
  
  
  RESULTS
  HITS were detected in more patients after implantation of a mechanical aortic valve prosthesis compared with a homograft aortic valve (16 versus 8, p=0.02). Nevertheless, more patients with a homograft aortic valve showed HITS than the control patients (8 versus 1, p=0.02). The mean number of HITS in the mechanical prosthesis group was higher than in the homograft group (3, range 0-18 versus 13, range 0-70, p<0.05). HITS in patients with mechanical prostheses had a higher amplitude than HITS in patients with homograft aortic valves (p<0.0001). Focal neurological deficit (FND) was diagnosed in 9 patients (mechanical prosthesis 6 versus homograft 3, ns).
  
  
  CONCLUSIONS
  HITS commonly occur both in patients with a mechanical aortic valve and in patients with a homograft aortic valve. HITS occur significantly less often, at a lower rate and with a lower intensity in patients with homograft aortic valve compared with patients with a mechanical aortic valve. Future studies should elucidate the nature and prognostic significance of HITS and their relationship with thromboembolic events.
authors.affiliation: Department of Cardiothoracic Surgery, University Hospital, Rotterdam, The Netherlands.
authors.forename: A M
authors.initials: AM
authors.lastname: Lievense
authors.forename: S L
authors.initials: SL
authors.lastname: Bakker
authors.forename: D W
authors.initials: DW
authors.lastname: Dippel
authors.forename: M A
authors.initials: MA
authors.lastname: Taams
authors.forename: P J
authors.initials: PJ
authors.lastname: Koudstaal
authors.forename: A J
authors.initials: AJ
authors.lastname: Bogers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000601:surgery* / Q000637:transplantation; D001672:Biocompatible Materials / Q000009:adverse effects; D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D002536:Cerebral Arteries / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D005260:Female; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000000981:diagnostic imaging / Q000601:surgery; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D006801:Humans; D002542:Intracranial Embolism and Thrombosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D014184:Transplantation, Homologous / Q000009:adverse effects; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D001672:Biocompatible Materials