Occurrence and clinical impact of microembolic signals during or after cardiosurgical procedures

Stroke

Volumn 39, Issue 2, 2008, Pages 503-511

  Dittrich, Ralf ^a,b   Ringelstein, E Bernd ^a  

^a UNIVERSITY OF MÜNSTER   (Germany)

^b UNIVERSITY HOSPITAL MÜNSTER   (Germany)

Author keywords

Cardiac embolism; Cardiac surgery; Cognitive impairment; Tcd; Transcranial Doppler; Ultrasound

Indexed keywords

ACETYLSALICYLIC ACID;

ASSISTED CIRCULATION; CARDIOPULMONARY BYPASS; DATA BASE; EXTRACORPOREAL CIRCULATION; HEART CATHETERIZATION; HEART SURGERY; HEART VALVE; HEART VALVE PROSTHESIS; HEART VALVE REPLACEMENT; HUMAN; MEDLINE; MICROEMBOLISM; OCCLUSIVE CEREBROVASCULAR DISEASE; PREVALENCE; PRIORITY JOURNAL; REVIEW; SYSTEMATIC REVIEW; TRANSLUMINAL CORONARY ANGIOPLASTY; BRAIN EMBOLISM; DOPPLER ECHOGRAPHY; ECHOGRAPHY; PATIENT MONITORING; PEROPERATIVE COMPLICATION; STATISTICS;

CARDIAC SURGICAL PROCEDURES; HUMANS; INTRACRANIAL EMBOLISM; INTRAOPERATIVE COMPLICATIONS; MONITORING, INTRAOPERATIVE; PREVALENCE; ULTRASONOGRAPHY, DOPPLER, TRANSCRANIAL;

EID: 39349097735     PISSN: 00392499     EISSN: None     Source Type: Journal    
DOI: 10.1161/STROKEAHA.107.491241     Document Type: Review

References (101)

1. Spencer MP, Campbell SD, Sealey JL, Henry FC, Lindbergh J. Experiments on decompression bubbles in the circulation using ultrasonic and electromagnetic flowmeters. Occup Med. 1969;11:238-244.
2. Spencer MP, Lawrence GH, Thomas GI, Sauvage LR. The use of ultrasonics in the determination of arterial aeroembolism during open heart surgery. Ann Thorac Surg. 1969;8:489-497.
3. Berger M, Davis D, Lolley D, Rams J, Spencer MP. Detection of subclinical microemboli in patients with prosthetic heart valves. J Cardiovasc Tech. 1990;9:282-283.
4. Grosset DG, Cowburn P, Georgiadis D, Dargie HJ, Faichney A, Lee KR. Ultrasound detection of cerebral emboli in patients with prosthetic heart valves. J Heart Valve Dis. 1994;3:128-132.
5. Braekken KS, Russell D, Brucher R, Svennevig J. Incidence and frequency of cerebral embolic signals in patients with a similar bileaflet mechanical valve. Stroke. 1995;26:1225-1230.
6. Georgiadis D, Kaps M, Siebler M, Hill M, Konig M, Berg J, Kahl M, Zunker P, Diehl B, Ringelstein EB. Variability of Doppler microembolic signal counts in patients with prosthetic cardiac valves. Stroke. 1995;26:439-443.
7. Muller HR, Burckhardt D, Casty M, Pfisterer ME, Buser MW. High intensity transcranial Doppler signals (HITS) after prosthetic valve implantation. Heart Valve Dis. 1994;3:602-606.
8. Georgiadis D, Grosset DG, Kelman A, Faichney A, Lees KR. Prevalence and characteristics of intracranial microemboli signals in patients with different types of prosthetic cardiac valves. Stroke. 1994;25:587-592.
9. Georgiadis D, Kaps M, Berg J, Mackay TG, Dapper F, Faichney A, Wheatley DJ, Lees KR. Transcranial Doppler detection of microemboli in prosthetic heart valve patients: dependency upon valve type. Eur J Cardiothorac Surg. 1996;10:253-257; discussion 257-258.
10. Grosset DG, Georgiadis D, Kelman AW, Cowburn P, Stirling S, Lees KR, Faichney A, Mallinson A, Quin R, Bone I, Pettigrew L, Brodie E, MacKay T, Wheatley DJ. Detection of microemboli by transcranial Doppler ultrasound. Tex Heart Inst J. 1996;23:289-292.
11. Deklunder G, Lecroart JL, Savoye C, Coquet B, Houdas Y. Transcranial high-intensity Doppler signals in patients with mechanical heart valve prostheses: their relationship with abnormal intracavitary echoes. J Heart Valve Dis. 1996;5:662-667.
12. Lindner A, Georgiadis D, Luhmann A, Stephan M, Preiss M, Zerkowski HR, Zierz S. Time course of high-intensity transient signals in patients undergoing elective heart valve replacement: a prospective study. J Heart Valve Dis. 1997;6:527-530.
13. Sliwka U, Georgiadis D. Clinical correlations of Doppler microembolic signals in patients with prosthetic cardiac valves: analysis of 580 cases. Stroke. 1998;29:140-143.
14. Milano A, D'Alfonso A, Codecasa R, De Carlo M, Nardi C, Orlandi G, Landucci L, Bortolotti U. Prospective evaluation of frequency and nature of transcranial high-intensity Doppler signals in prosthetic valve recipients. J Heart Valve Dis. 1999;8:488-494.
15. Eicke BM, Barth V, Kukowski B, Werner G, Paulus W. Cardiac microembolism: prevalence and clinical outcome. J Neurol Sci. 1996;136:143-147.
16. Georgiadis D, Lindner A, Manz M, Sonntag M, Zunker P, Zerkowski HR, Borggrefe M. Intracranial microembolic signals in 500 patients with potential cardiac or carotid embolic source and in normal controls. Stroke. 1997;28:1203-1207.
17. Lievense AM, Bakker SL, Dippel DW, Taams MA, Koudstaal PJ, Bogers AJ. Intracranial high-intensity transient signals after homograft or mechanical aortic valve replacement. J Cardiovasc Surg (Torino). 1998;39:613-617.
18. Georgiadis D, Wenzel A, Lehmann D, Lindner A, Zerkowski HR, Zierz S, Spencer MP. Influence of oxygen ventilation on Doppler microemboli signals in patients with artificial heart valves. Stroke. 1997;28:2189-2194.
19. Georgiadis D, Baumgartner RW, Karatschai R, Lindner A, Zerkowski HR. Further evidence of gaseous embolic material in patients with artificial heart valves. J Thorac Cardiovasc Surg. 1998;115:808-810.
20. Sturzenegger M, Beer JH, Rihs F. Monitoring combined antithrombotic treatments in patients with prosthetic heart valves using transcranial Doppler ultrasound. Stroke. 1995;26:63-69.
21. Kofidis T, Fischer S, Leyh R, Maier H, Deckert M, Haberl R, Haverich A, Reichert B. Clinical relevance of intracranial high intensity transient signals in patients following prosthetic aortic valve replacement. Eur J Cardiothorac Surg. 2002;21:22-26.
22. Nadareishvili ZG, Beletsky V, Black SE, Fremes SE, Freedman M, Kurzman D, Leach L, Norris JW. Is cerebral microembolism in mechanical prosthetic heart valves clinically relevant? J Neuroimaging. 2002;12:310-315.
23. Droste DW, Dittrich R, Hermes S, Kemeny V, Schulte-Altedorneburg G, Hansberg T, Ringelstein EB. Four-gated transcranial Doppler ultrasound in the detection of circulating microemboli. Eur J Ultrasound. 1999;9:117-125.
24. Kaps M, Hansen J, Weiher M, Tiffert K, Kayser I, Droste DW. Clinically silent microemboli in patients with artificial prosthetic aortic valves are predominately gaseous and not solid. Stroke. 1997;28:322-325.
25. Laas J, Kseibi S, Perthel M, Klingbeil A, El-Ayoubi L, Alken A. Impact of high intensity transient signals on the choice of mechanical aortic valve substitutes. Eur J Cardiothorac Surg. 2003;23:93-96.
26. Droste DW, Hansberg T, Kemeny V, Hammel D, Schulte-Altedorneburg G, Nabavi DG, Kaps M, Scheld HH, Ringelstein EB. Oxygen inhalation can differentiate gaseous from nongaseous microemboli detected by transcranial Doppler ultrasound. Stroke. 1997;28:2453-2456.
27. Deklunder G, Roussel M, Lecroart JL, Prat A, Gautier C. Microemboli in cerebral circulation and alteration of cognitive abilities in patients with mechanical prosthetic heart valves. Stroke. 1998;29:1821-1826.
28. Uekermann J, Suchan B, Daum I, Kseibi S, Perthel M, Laas J. Neuropsychological deficits after mechanical aortic valve replacement. J Heart Valve Dis. 2005;14:338-343.
29. Geiser T, Sturzenegger M, Genewein U, Haeberli A, Beer JH. Mechanisms of cerebrovascular events as assessed by procoagulant activity, cerebral microemboli, and platelet microparticles in patients with prosthetic heart valves. Stroke. 1998;29:1770-1777.
30. Hiratsuka R, Fukunaga S, Tayama E, Takagi K, Arinaga K, Shojima T, Teshima H, Aoyagi S. High-intensity transient signals due to prosthetic valve obstruction: diagnostic and therapeutic implications. Ann Thorac Surg. 2004;77:1615-1621.
31. Pennington DG, McBride LR, Peigh PS, Miller LW, Swartz MT. Eight years' experience with bridge to cardiac transplantation. J Thorac Cardiovasc Surg. 1994;107:472-481.
32. Nabavi DG, Georgiadis D, Mumme T, Schmid C, Mackay TG, Scheld HH, Ringelstein EB. Clinical relevance of intracranial microembolic signals in patients with left ventricular assist devices: a prospective study. Stroke. 1996;27:891-896.
33. Moazami N, Roberts K, Argenziano M, Catanese K, Mohr JP, Rose EA, Oz MC. Asymptomatic microembolism in patients with long-term ventricular assist support. ASAIO J. 1997;43:177-180.
34. Schmid C, Weyand M, Nabavi DG, Hammel D, Deng MC, Ringelstein EB, Scheld HH. Cerebral and systemic embolization during left ventricular support with the Novacor N100 device. Ann Thorac Surg. 1998;65:1703-1710.
35. Wilhelm CR, Ristich J, Knepper LE, Holubkov R, Wisniewski SR, Kormos RL, Wagner WR. Measurement of hemostatic indexes in conjunction with transcranial Doppler sonography in patients with ventricular assist devices. Stroke. 1999;30:2554-2561.
36. Potapov EV, Nasseri BA, Loebe M, Kukucka M, Koster A, Kuppe H, Noon GP, DeBakey ME, Hetzer R. Transcranial detection of microembolic signals in patients with a novel nonpulsatile implantable LVAD. ASAIO J. 2001;47:249-253.
37. Nabavi DG, Stockmann J, Schmid C, Schneider M. Hammel D. Scheld HH, Ringelstein EB. Doppler microembolic load predicts risks of thromboembolic complications in Novacor patients. J Thorac Cardiovasc Surg. 2003;126:160-167.
38. Thoennissen NH, Schneider M. Allroggen A, Ritter M, Dittrich R, Schmid C, Scheld HH, Ringelstein EB, Nabavi DG. High level of cerebral microembolization in patients supported with the DeBakey left ventricular assist device. J Thorac Cardiovasc Surg. 2005;130:1159-1166.
39. Thoennissen NH, Allroggen A, Dittrich R, Ritter M, Schmid C, Scheld HH, Ringelstein EB, Nabavi DG. Can Doppler time domain analysis of microembolic signals discriminate between gaseous and solid microemboli in patients with left ventricular assist device? Neurol Res. 2005;27:780-784.
40. Thoennissen NH, Allroggen A, Ritter M, Dittrich R, Schmid C, Schmid HH, Ringelstein EB, Nabavi DG. Influence of inflammation and pump dynamic on cerebral microembolization in patients with continuous-flow DeBakey LVAD. ASAIO J. 2006;52:243-247.
41. Blauth CI. Macroemboli and microemboli during cardiopulmonary bypass. Ann Thorac Surg. 1995;59:1300-1303.
42. Baker AJ, Naser B, Benaroia M, Mazer CD. Cerebral microemboli during coronary artery bypass using different cardioplegia techniques. Ann Thorac Surg. 1995;59:1187-1191.
43. Clark RE, Brillman J, Davis DA, Lovell MR, Price TR, Magovern GJ. Microemboli during coronary artery bypass grafting: genesis and effect on outcome. J Thorac Cardiovasc Surg. 1995;109:249-258.
44. Barbut D, Hinton RB, Szatrowski TP, Hartman GS, Bruefach M, Williams-Russo P, Charlson ME, Gold JP. Cerebral emboli detected during bypass surgery are associated with clamp removal. Stroke. 1994;25:2398-2402.
45. Barbut D, Yao FS, Hager DN, Kavanaugh P, Trifiletti PR, Gold JP. Comparison of transcranial Doppler ultrasonography and transesophageal echocardiography to monitor emboli during coronary artery bypass surgery. Stroke. 1996;27:87-90.
46. Guerrieri Wolf L, Abu-Omar Y, Choudhary BP, Pigott D, Taggart DP. Gaseous and solid cerebral microembolization during proximal aortic anastomoses in off-pump coronary surgery: the effect of an aortic side-biting clamp and two clampless devices. J Thorac Cardiovasc Surg. 2007;133:485-493.
47. Rodriguez RA, Rubens F, Belway D, Nathan HJ. Residual air in the venous cannula increases cerebral embolization at the onset of cardiopulmonary bypass. Eur J Cardiothorac Surg. 2006;29:175-180.
48. Pugsley W, Klinger L, Paschalis C, Treasure T, Harrison M, Newman S. The impact of microemboli during cardiopulmonary bypass on neuropsychological functioning. Stroke. 1994;25:1393-1399.
49. Jacobs A, Neveling M, Horst M, Ghaemi M, Kessler J, Eichstaedt H, Rudolf J, Model P, Bonner H, de Vivie ER, Heiss WD. Alterations of neuropsychological function and cerebral glucose metabolism after cardiac surgery are not related only to intraoperative microembolic events. Stroke. 1998;29:660-667.
50. Lee JD, Lee SJ, Tsushima WT, Yamauchi H, Lau WT, Popper J, Stein A, Johnson D, Lee D, Petrovitch H, Dang CR. Benefits of off-pump bypass on neurologic and clinical morbidity: a prospective randomized trial. Ann Thorac Surg. 2003;76:18-26.
51. Bokeriia LA, Golukhova EZ, Breskina NY, Polunina AG, Davydov DM, Begachev AV, Kazanovskaya SN. Asymmetric cerebral embolic load and postoperative cognitive dysfunction in cardiac surgery. Cerebrovasc Dis. 2006;23:50-56.
52. Abu-Omar Y, Cader S, Guerrieri Wolf L, Pigott D, Matthews PM, Taggart DP. Short-term changes in cerebral activity in on-pump and off-pump cardiac surgery defined by functional magnetic resonance imaging and their relationship to microembolization. J Thorac Cardiovasc Surg. 2006;132:1119-1125.
53. Sylivris S, Levi C, Matalanis G, Rosalion A, Buxton BF, Mitchell A. Fitt G, Harberts DB, Saling MM, Tonkin AM. Pattern and significance of cerebral microemboli during coronary artery bypass grafting. Ann Thorac Surg. 1998;66:1674-1678.
54. Braekken SK, Reinvang I, Russell D, Brucher R, Svennevig JL. Association between intraoperative cerebral microembolic signals and postoperative neuropsychological deficit: comparison between patients with cardiac valve replacement and patients with coronary artery bypass grafting. J Neurol Neurosurg Psychiatry. 1998;65:573-576.
55. Diegeler A, Hirsch R, Schneider F, Schilling LO, Falk V, Rauch T, Mohr FW. Neuromonitoring and neurocognitive outcome in off-pump versus conventional coronary bypass operation. Ann Thorac Surg. 2000;69:1162-1166.
56. Browndyke JN, Moser DJ, Cohen RA, O'Brien DJ, Algina JJ, Haynes WG, Staples ED, Alexander J, Davies LK, Bauer RM. Acute neuropsychological functioning following cardiosurgical interventions associated with the production of intraoperative cerebral microemboli. Clin Neuropsychol. 2002;16:463-471.
57. Stygall J, Newman SP, Fitzgerald G, Steed L, Mulligan K, Arrowsmith JE, Pugsley W, Humphries S, Harrison MJ. Cognitive change 5 years after coronary artery bypass surgery. Health Psychol. 2003;22:579-586.
58. Neville MJ, Butterworth J, James RL, Hammon JW, Stump DA. Similar neurobehavioral outcome after valve or coronary artery operations despite differing carotid embolic counts. J Thorac Cardiovasc Surg. 2001;121:125-136.
59. Taylor RL, Borger MA, Weisel RD, Fedorko L, Feindel CM. Cerebral microemboli during cardiopulmonary bypass: increased emboli during perfusionist interventions. Ann Thorac Surg. 1999;68:89-93.
60. Borger MA, Peniston CM, Weisel RD, Vasiliou M, Green REA, Feindel CM. Neuropsychologic impairment after coronary bypass surgery: effect of gaseous microemboli during perfusionist interventions. J Thorac Cardiovasc Surg. 2001;121:743-749.
61. Rodriguez RA, Williams KA, Babaev A, Rubens F, Nathan HJ. Effect of perfusionist technique on cerebral embolization during cardiopulmonary bypass. Perfusion. 2005;20:3-10.
62. Rudolph JL, Tilahun D, Treanor PR, Pochay VE, Mahendrakar MA, Sagar P, Babikian VL. Use of a large bore syringe creates significantly fewer high intensity transient signals (HITS) into a cardiopulmonary bypass system than a small bore syringe. Perfusion. 2006;21:67-71.
63. 2 insufflation on the number and behavior of air microemboli in open-heart surgery: a randomized clinical trial. Circulation. 2004;109:1127-1132.
64. Bhasker Rao B, Van Himbergen D, Edmonds HL Jr, Jaber S, Ali AT, Pagni S, Koenig S, Spence PA. Evidence for improved cerebral function after minimally invasive bypass surgery. J Card Surg. 1998;13:27-31.
65. Watters MPR, Cohen AM, Monk CR, Angelini GD, Ryder IG. Reduced cerebral embolic signals in beating heart coronary surgery detected by transcranial Doppler ultrasound. Br J Anaesth. 2000;84:629-631.
66. Bowles BJ, Lee JD, Dang CR, Taoka SN, Johnson EW, Lau EM, Nekomoto K. Coronary artery bypass performed without the use of cardiopulmonary bypass is associated with reduced cerebral microemboli and improved clinical results. Chest. 2001;119:25-30.
67. Lund C, Hol PK, Lundblad R, Fosse E, Sundet K, Tennoe B, Brucher R, Russell D. Comparison of cerebral embolization during off-pump and on-pump coronary artery bypass surgery. Ann Thorac Surg. 2003;76:765-770.
68. Abu-Omar Y, Balacumaraswami L, Pigott DW, Matthews PM, Taggart DP. Solid and gaseous cerebral microembolization during off-pump, on-pump, and open cardiac surgery procedures. J Thorac Cardiovasc Surg. 2004;127:1759-1765.
69. Motallebzadeh R, Kanagasabay R, Bland M, Kaski JC, Jahangiri M. S100 protein and its relation to cerebral microemboli in on-pump and off-pump coronary artery bypass surgery. Eur J Cardiothorac Surg. 2004;25:409-414.
70. Ascione R, Ghosh A, Reeves BC, Arnold J, Potts M, Shah A, Angelini GD. Retinal and cerebral microembolization during coronary artery bypass surgery: a randomized, controlled trial. Circulation. 2005;112:3833-3838.
71. Stroobant N, Van Nooten G, Van Belleghem Y, Vingerhoets G. Relation between neurocognitive impairment, embolic load, and cerebrovascular reactivity following on- and off-pump coronary artery bypass grafting. Chest. 2005;127:1967-1976.
72. Scarborough JE, White W, Derilus FE, Mathew JP, Newman MF, Landolfo KP; Neurological Outcome Research Group. Combined use of off-pump techniques and a sutureless proximal aortic anastomotic device reduces cerebral microemboli generation during coronary artery bypass grafting. J Thorac Cardiovasc Surg. 2003;126:1561-1567.
73. Padayachee TS, Parsons S, Theobold R, Gosling RG, Deverall PB. The effect of arterial filtration on reduction of gaseous microemboli in the middle cerebral artery during cardiopulmonary bypass. Ann Thorac Surg. 1988;45:647-649.
74. Eifert S, Reichenspurner H, Pfefferkorn T, Baur B, von Schlippenbach C, Mayer TE, Hamann G, Reichart B. Neurological and neuropsychological examination and outcome after use of an intra-aortic filter device during cardiac surgery. Perfusion. 2003;18(suppl 1):55-60.
75. Schoenburg M, Kraus B, Muehling A, Taborski U, Hofmann H, Erhardt G, Hein S, Roth M, Vogt PR, Karliczek GF, Kloevekorn WP. The dynamic air bubble trap reduces cerebral microembolism during cardiopulmonary bypass. J Thorac Cardiovasc Surg. 2003;126:1455-1460.
76. Whitaker DC, Newman SP, Stygall J, Hope-Wynne C, Harrison MJ, Walesby RK. The effect of leucocyte-depleting arterial line filters on cerebral microemboli and neuropsychological outcome following coronary artery bypass surgery. Eur J Cardiothorac Surg. 2004;25:267-274.
77. de Vries AJ, Gu YJ, Douglas YL, Post WJ, Lip H, van Oeveren W. Clinical evaluation of a new fat removal filter during cardiac surgery. Eur J Cardiothorac Surg. 2004;25:261-266.
78. Perthel M, Kseibi S, Bendisch A, Laas J. Use of a dynamic bubble trap in the arterial line reduces microbubbles during cardiopulmonary bypass and microembolic signals in the middle cerebral artery. Perfusion. 2005;20:151-156.
79. Schonburg M, Ziegelhoeffer T, Kraus B, Muhling A, Heidt M, Taborski U, Gerriets T, Roth M, Hein S, Urbanek S, Klovekorn WP. Reduction of gaseous microembolism during aortic valve replacement using a dynamic bubble trap. Gen Physiol Biophys. 2006;25:207-214.
80. Brown WR, Moody DM, Challa VR, Stump DA, Hammon JW. Longer duration of cardiopulmonary bypass is associated with greater numbers of cerebral microemboli. Stroke. 2000;31:707-713.
81. Milsom FP, Mitchell SJ.A. dual-vent left heart deairing technique markedly reduces carotid artery microemboli. Ann Thorac Surg. 1998;66:785-791.
82. Borger MA, Taylor RL, Weisel RD, Kulkarni G, Benaroia M, Rao V, Cohen G, Fedorko L, Feindel CM. Decreased cerebral emboli during distal aortic arch cannulation: a randomized clinical trial. J Thorac Cardiovasc Surg. 1999;118:740-745.
83. Mullges W, Franke D, Reents W, Babin-Ebell J. Brain microembolic counts during extracorporeal circulation depend on aortic cannula position. Ultrasound Med Biol. 2001;27:933-936.
84. Benaroia M, Baker AJ, Mazer CD, Errett L. Effect of aortic cannula characteristics and blood velocity on transcranial Doppler-detected microemboli during cardiopulmonary bypass. Cardiothorac Vasc Anesth. 1998;12:266-269.
85. Mullges W, Franke D, Reents W, Babin-Ebell J, Toyka KV. Reduced rate of microembolism by optimized aortic cannula position does not influence early postoperative cognitive performance in CABG patients. Cerebrovasc Dis. 2003;15:192-198.
86. Georgiadis D, Stets R, Schorch A, Baumgartner RW, Bernet F, Zerkowski HR. Doppler microembolic signals during cardiopulmonary bypass: comparison of two membrane oxygenators. Neurol Res. 2004;26:99-102.
87. Rodriguez RA, Watson MI, Nathan HJ, Rubens F. Do surface-modifying additive circuits reduce the rate of cerebral microemboli during cardiopulmonary bypass? J Extra Corpor Technol. 2006;38:216-219.
88. Schneider F, Onnasch JF, Falk V, Walther T, Autschbach R, Mohr FW. Cerebral microemboli during minimally invasive and conventional mitral valve operations. Ann Thorac Surg. 2000;70:1094-1097.
89. Skjelland M, Bergsland J, Lundblad R, Lingaas PS, Rein KA, Halvorsen S, Svennevig JL, Fosse E, Brucher R, Russell D. Cerebral microembolization during off-pump coronary artery bypass surgery with the Symmetry aortic connector device J Thorac Cardiovasc Surg. 2005;130:1581-1585.
90. Mullges W, Berg D, Toyka KV. Bilateral cerebral emboli monitoring during extracorporeal circulation. Ultrasound Med Biol. 1999;25:755-758.
91. Moser DJ, Ferneyhough KC, Bauer RM, Arndt S, Schultz SK, Haynes WG, Staples ED, Alexander J, Davies LK, O'Brien DJ. Unilateral vs. bilateral ultrasound in the monitoring of cerebral microemboli. Ultrasound Med Biol. 2001;27:757-760.
92. Feerick AE, Church JA, Zwischenberger J, Conti V, Johnston WE. Systemic gaseous microemboli during left atrial catheterization: a common occurrence? J Cardiothorac Vasc Anesth. 1995;9:395-398.
93. Stygall J, Kong R, Walker JM, Hardman SM, Harrison MJ, Newman SP. Cerebral microembolism detected by transcranial Doppler during cardiac procedures. Stroke. 2000;31:2508-2510.
94. Bladin CF, Bingham L, Grigg L, Yapanis AG, Gerraty R, Davis SM. Transcranial Doppler detection of microemboli during percutaneous transluminal coronary angioplasty. Stroke. 1998;29:2367-2370.
95. Leclercq F, Kassnasrallah S, Cesari JB, Blard JM, Macia JC, Messner-Pellenc P, Mariottini CJ, Grolleau-Raoux R. Transcranial Doppler detection of cerebral microemboli during left heart catheterization. Cerebrovasc Dis. 2001;12:59-65.
96. Fischer A, Ozbek C, Bay W, Hamann GF. Cerebral microemboli during left heart catheterization. Am Heart J. 1999;137:162-168.
97. Braekken SK, Endresen K, Russell D, Brucher R, Kjekshus J. Influence of guidewire and catheter type on the frequency of cerebral microembolic signals during left heart catheterization. Am J Cardiol. 1998;82:632-637.
98. Lund C, Nes RB, Ugelstad TP, Due-Tonnessen P, Andersen R, Hol PK, Brucher R, Russell D. Cerebral emboli during left heart catheterization may cause acute brain injury. Eur Heart J. 2005;26:1269-1275.
99. Hamon M, Gomes S, Oppenheim C, Morello R, Sabatier R, Lognone T, Grollier G, Courtheoux P, Hamon M. Cerebral microembolism during cardiac catheterization and risk of acute brain injury: a prospective diffusion-weighted magnetic resonance imaging study. Stroke. 2006;37:2035-2038.
100. Russell D, Brucher R. Online automatic discrimination between solid and gaseous cerebral microemboli with the first multifrequency transcranial Doppler. Stroke. 2002;33:1975-1980.
101. Smith JL, Evans DH, Bell PR, Naylor AR. A comparison of four methods for distinguishing Doppler signals from gaseous and particulate emboli. Stroke. 1998;29:1133-1138.