Raja, Yogesh

Varma, Chetan

Watson, Timothy

English

Via Medica Journals

415www.cardiologyjournal.orgIMAGES IN CARDIOLOGYCardiology Journal2007, Vol. 14, No. 4, pp. 415–416Copyright © 2007 Via MedicaISSN 1897–5593Address for correspondence: Dr. Chetan VarmaCity Hospital, Birmingham, United Kingdom B18 7QHTel: +44 (0) 121 507, fax: +44 (0) 121 507e-mail: chetan.varma@swbh.nhs.ukHigh-intensity transient signalsYogesh Raja, Timothy Watson and Chetan VarmaDepartment of Cardiology, City Hospital, Birmingham, United KingdomAn asymptomatic 33 year-old Caucasian male pre-sented for routine imaging following a St. Jude’s bi-lea-flet aortic valve replacement some 6 months previously.The images show high-intensity transient sig-nals (HITS) just below the aortic valve in both par-asternal and apical long axis views. The valve re-placement otherwise appeared healthy.HITS are thought to be microbubbles whichoccur due to cavitation associated with the dynam-ics of mechanical valve closure [1]. They are morecommon with mitral valve prostheses, possibly be-cause of greater turbulence [2]. The phenomenonhas also been described with bioprosthetic valves,but there is no known association with mitral valverepair or homografts [3].Some patients with this phenomenon have in-creased levels of lactate dehydrogenase, potential-ly representing hemolysis [4]. Curiously, duringinhalation of oxygen, a significant decrease in thenumber of HITS has been reported, supporting thehypothesis of the gaseous nature of such signals [1].HITS can also be detected by trans-cranial Doppler,but the exact significance of these microemboli re-mains uncertain. An association with cognitive im-pairment has been described, whilst others havesuggested that they are benign in nature [5].416Cardiology Journal 2007, Vol. 14, No. 4www.cardiologyjournal.orgReferences1. Rambod E, Beizaie M, Shusser M, Milo S, Gharib M.A physical model describing the mechanism for forma-tion of gas microbubbles in patients with mitral mechan-ical heart valves. Ann Biomed Eng, 1999; 27: 774–792.2. Deklunder G, Lecroart JL, Savoye C, Coquet B,Houdas Y. Transcranial high-intensity Doppler sig-nals in patients with mechanical heart valve prosthe-ses: their relationship with abnormal intracavitaryechoes. J Heart Valve Dis, 1996; 5: 662–667.3. Milano A, D’Alfonso A, Codecasa R et al. Prospec-tive evaluation of frequency and nature of transcranialhigh-intensity Doppler signals in prosthetic valverecipients. J Heart Valve Dis, 1999; 8: 488–494.4. Gencbay M, Degertekin M, Basaran Y et al. Micro-bubbles associated with mechanical heart valves:their relation with serum lactic dehydrogenase levels.Am Heart J, 1999; 137: 463–468.5. Nadareishvili ZG, Beletsky V, Black SE et al. Is cere-bral microembolism in mechanical prosthetic heart valvesclinically relevant? J Neuroimaging, 2002; 12: 310–315.

High-intensity transient signals

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High-intensity transient signals

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