title: Clinically silent cerebral ischemic events after cardiac surgery: their incidence, regional vascular occurrence, and procedural dependence.
abstract: BACKGROUND
  The reported frequency of stroke after coronary artery bypass grafting varies between 1.5% and 6%, approaches 10% after aortic valve replacement, and may occur in between 40 to 70% in high-risk groups. Clinically silent infarction may be far more frequent and could contribute to long-term cognitive dysfunction in patients after cardiac procedures. Using diffusion-weighted magnetic resonance imaging we document the occurrence, vascular distribution, and procedural dependence of silent infarction after cardiac surgery with cardiopulmonary bypass. We also document the association of preexisting white matter lesions with new postoperative ischemic lesions.
  
  
  METHODS
  Thirty-four patients underwent T2-weighted fluid attenuated inversion recovery and diffusion-weighted magnetic resonance imaging before and after cardiac surgery with cardiopulmonary bypass for coronary artery bypass grafting, aortic valve replacement, and mitral valve repair or replacement surgery. Images were evaluated by experienced neuroradiologists for number, size, and vascular distribution of lesions.
  
  
  RESULTS
  Mean age of participants was 67 +/- 15 years. Imaging occurred before and 6 +/- 2 days after surgery. New cerebral infarctions were evident in 6 of 34 patients (18%), were often multiple, and in 67% of patients were clinically silent. The occurrence of new infarctions by surgical procedure was as follows: aortic valve replacement (2 of 6), coronary artery bypass grafting and aortic valve replacement (3 of 8), aortic valve replacement with root replacement (1 of 1), coronary artery bypass grafting and mitral valve repair or replacement (0 of 4), mitral valve repair or replacement (0 of 2), and isolated coronary artery bypass grafting (0 of 13). New infarction occurred in 6 of 15 (40%) of all procedures involving aortic valve replacement. The severity of preexisting white matter lesions trended toward predicting the occurrence of new lesions (p = 0.055).
  
  
  CONCLUSIONS
  Diffusion-weighted imaging reveals new cerebral infarctions in nearly 40% of patients after aortic valve replacement.
authors.affiliation: Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvani, USA. floydt@uphs.upenn.edu
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Floyd
authors.forename: Pallav N
authors.initials: PN
authors.lastname: Shah
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Price
authors.forename: Francis
authors.initials: F
authors.lastname: Harris
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Ratcliffe
authors.forename: Michael A
authors.initials: MA
authors.lastname: Acker
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Bavaria
authors.forename: Hind
authors.initials: H
authors.lastname: Rahmouni
authors.forename: Bettina
authors.initials: B
authors.lastname: Kuersten
authors.forename: Susan
authors.initials: S
authors.lastname: Wiegers
authors.forename: Michael L
authors.initials: ML
authors.lastname: McGarvey
authors.forename: Joseph Y
authors.initials: JY
authors.lastname: Woo
authors.forename: Alberto A
authors.initials: AA
authors.lastname: Pochettino
authors.forename: Elias R
authors.initials: ER
authors.lastname: Melhem
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001018:Aortic Diseases / Q000000981:diagnostic imaging / Q000473:pathology; D001021:Aortic Valve / Q000601:surgery; D050197:Atherosclerosis / Q000000981:diagnostic imaging / Q000473:pathology; D002545:Brain Ischemia / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology; D006348:Cardiac Surgical Procedures / Q000379:methods / Q000706:statistics & numerical data; D002315:Cardiopulmonary Bypass; D002544:Cerebral Infarction / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000473:pathology; D015897:Comorbidity; D001026:Coronary Artery Bypass; D038524:Diffusion Magnetic Resonance Imaging; D017548:Echocardiography, Transesophageal; D005260:Female; D006344:Heart Septal Defects, Atrial / Q000000981:diagnostic imaging; D006349:Heart Valve Diseases / Q000601:surgery; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery; D010414:Pennsylvania / Q000453:epidemiology; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology; D016037:Single-Blind Method; D018084:Ultrasonography, Interventional