title: Further evidence of gaseous embolic material in patients with artificial heart valves.
abstract: OBJECTIVE
  We undertook this study to evaluate the hypothesis that most microemboli signals in patients with artificial heart valves are gaseous, assuming that microemboli counts in cerebral arteries would progressively decline with increasing distance from the generating heart valve.
  
  
  METHODS
  A total of 10 outpatients with CarboMedics (Sulzer Carbomedics Inc., n = 5) and ATS prosthetic heart valves (n = 5) in the aortic (n = 8), mitral (n = 1), or both aortic and mitral positions (n = 1) were recruited. Monitoring was performed simultaneously over the middle and anterior cerebral arteries and the common carotid artery for 30 minutes with the 2 MHZ transducers of a color duplex scanner (common carotid artery) and pulsed-wave Doppler ultrasonography (intracranial arteries). All data were harvested in an eight-channel digital audio tape recorder, and microembolic signal counts were evaluated online by two separate observers.
  
  
  RESULTS
  Significantly higher microembolic signal counts were recorded in the common carotid artery (112 [75 to 175]) compared with the middle and anterior cerebral arteries (30 [18 to 36], p < 0.0001). Interobserver variability was satisfactory (k = 0.81).
  
  
  CONCLUSIONS
  Our results strongly argue for gaseous underlying embolic material in patients with artificial heart valves because bubbles are bound to implode with time.
authors.affiliation: Department of Neurology, University of Halle, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Georgiadis
authors.forename: R W
authors.initials: RW
authors.lastname: Baumgartner
authors.forename: R
authors.initials: R
authors.lastname: Karatschai
authors.forename: A
authors.initials: A
authors.lastname: Lindner
authors.forename: H R
authors.initials: HR
authors.lastname: Zerkowski
mesh_terms: D000328:Adult; D001021:Aortic Valve; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging; D004618:Embolism, Air / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D002542:Intracranial Embolism and Thrombosis / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008943:Mitral Valve; D015588:Observer Variation; D018608:Ultrasonography, Doppler; D017585:Ultrasonography, Doppler, Transcranial