Document Detail

Prospective evaluation of frequency and nature of transcranial high-intensity Doppler signals in prosthetic valve recipients.
MedLine Citation:
PMID:  10517388     Owner:  NLM     Status:  MEDLINE    
BACKGROUND AND AIM OF THE STUDY: In asymptomatic prosthetic valve recipients, high-intensity transient signals (HITS) observed with transcranial Doppler (TCD) are a phenomenon of obscure clinical relevance which nature has not yet been elucidated convincingly. METHODS: Eighty-three patients without carotid disease, history of cerebrovascular accidents, and with negative preoperative TCD undergoing either valve replacement (mitral, n = 11; aortic, n = 56; mitral + aortic, n = 6; 40 mechanical prostheses, 29 biological prostheses, 10 homografts) or mitral repair (n = 10) were evaluated prospectively by means of TCD at discharge, three months and one year after surgery, to analyze the presence, incidence and characteristics of HITS. Furthermore, in 12 patients positive for HITS, TCD was repeated during a 30-min period of 100% O2 inhalation. RESULTS: Twenty-five patients (30%) were positive for HITS at all postoperative controls, although no neurological symptoms were observed. Mechanical prostheses showed a significantly higher incidence of HITS (85%) than biological prostheses (10%, p <0.001), repaired mitral valves (0%, p <0.001) and homografts (0%, p <0.001). At multivariate analysis the presence of a mechanical prosthesis was the only significant predictor of detection of HITS after valve replacement. During O2 inhalation, a significant decrease in the number of HITS per hour (55 +/- 79 versus 22 +/- 31, p = 0.002) occurred, which returned to initial values when room-air breathing was resumed. CONCLUSIONS: Prosthetic valve replacement, particularly when mechanical devices are used, is associated with the generation of HITS which persist throughout the follow up period, but remain clinically silent. The decrease of HITS during O2 inhalation strongly supports the hypothesis of the gaseous nature of such signals and confirms the validity of this method in helping to differentiate gaseous microemboli from solid microemboli in prosthetic valve recipients.
A Milano; A D'Alfonso; R Codecasa; M De Carlo; C Nardi; G Orlandi; L Landucci; U Bortolotti
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of heart valve disease     Volume:  8     ISSN:  0966-8519     ISO Abbreviation:  J. Heart Valve Dis.     Publication Date:  1999 Sep 
Date Detail:
Created Date:  1999-11-04     Completed Date:  1999-11-04     Revised Date:  2006-05-04    
Medline Journal Info:
Nlm Unique ID:  9312096     Medline TA:  J Heart Valve Dis     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  488-94     Citation Subset:  IM    
Cardio-Thoracic Department, University of Pisa Medical School, Italy.
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MeSH Terms
Aged, 80 and over
Aortic Valve / surgery
Carotid Arteries / ultrasonography
Embolism / etiology,  ultrasonography*
Follow-Up Studies
Heart Valve Prosthesis Implantation / adverse effects*
Middle Aged
Mitral Valve / surgery
Multivariate Analysis
Prospective Studies
Ultrasonography, Doppler, Transcranial*

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