ATS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Ann Thorac Surg 2008;86:1563-1569. doi:10.1016/j.athoracsur.2008.07.021
© 2008 The Society of Thoracic Surgeons
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Takaaki Koshiji
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Maekawa, K.
Right arrow Articles by Koshiji, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Maekawa, K.
Right arrow Articles by Koshiji, T.
Related Collections
Right arrow Cerebral protection

Original Articles: Adult Cardiac

Abnormalities in the Brain Before Elective Cardiac Surgery Detected by Diffusion-Weighted Magnetic Resonance Imaging

Kengo Maekawa, MDa,*, Tomoko Goto, MDa, Tomoko Baba, MDa, Atsushi Yoshitake, MDa, Shoji Morishita, MDb, Takaaki Koshiji, MDc

a Department of Anesthesiology, Kumamoto Chuo Hospital, Kumamoto, Japan
b Department of Radiology, Kumamoto Chuo Hospital, Kumamoto, Japan
c Department of Cardiovascular Surgery, Kumamoto Chuo Hospital, Kumamoto, Japan

Accepted for publication July 8, 2008.

* Address correspondence to Dr Maekawa, Department of Anesthesiology, Kumamoto Chuo Hospital, 1-5-1 Tainoshima, Kumamoto, 862-0965, Japan (Email: kenchom{at}par.odn.ne.jp).


   Abstract
Top
 Abstract
Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
 References
 
Background: Diffusion-weighted magnetic resonance imaging (DWI) has found ischemic lesions in the brain after cardiac surgery. However, preoperative cerebral injury has not been studied closely. In this study, we used DWI to assess the prevalence of abnormalities in patients scheduled for cardiac surgery.

Methods: We used conventional magnetic resonance imaging and DWI to study 247 consecutive patients scheduled for elective cardiac surgery. Clinical characteristics, neuropsychological test performance, and radiographic data were collected and compared with a group of patients who had normal findings on DWI.

Results: Eleven of the 247 patients (4.5%) had cerebral ischemic lesions on DWI before surgery. Compared with patients who had normal findings on DWI, patients who had abnormalities had significantly higher rates of history of cerebrovascular disease (64% versus 12%), cardiac catheterization within 14 days before DWI (91% versus 54%), preoperative cerebral infarctions (45% versus 5%), carotid artery stenosis (36% versus 5%), and preoperative cognitive impairment (55% versus 9%). Of the 11 patients with DWI abnormalities, 5 had delayed elective surgery and follow-up image studies; of these 5, 4 showed no relevant ischemic lesion on preoperative follow-up imaging. Among the other 6 patients, 1 had an infarction due to expansion of the same lesion that was detected on the preoperative DWI. There was no significant difference with regard to the incidence of postoperative stroke and cognitive dysfunction.

Conclusions: In all, 4.5% of cardiac surgery patients had existing cerebral ischemic lesions on DWI without obvious neurologic defects. Further studies are required to determine whether the lesions are associated with postoperative cognitive dysfunction or stroke.


   Introduction
Top
 Abstract
 Introduction
Material and Methods
 Results
 Comment
 Acknowledgments
 References
 
Neurologic dysfunction after cardiac surgery is a devastating complication that is associated with increased mortality and prolonged hospitalization [1]. Several studies have suggested that the etiology of cerebral injury during cardiopulmonary bypass (CPB) is related to several risk factors [2, 3]. In a previous study, we found that presurgical cerebral ischemic disorders, such as small infarctions, predicted postoperative stroke [4], although most patients with numerous small infarctions were asymptomatic and manifested no clinical signs.

Recently, advances in neuroimaging techniques, including cerebral magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) sequences, have found new ischemic lesions in a substantial number of patients after coronary artery bypass grafting [5–7]. Moreover, DWI has revealed that asymptomatic embolic cerebral infarctions may occur at an unexpectedly high rate after cardiac catheterization [8–10]. Although diagnostic and therapeutic cardiac catheterization is the most common endovascular procedure before cardiac surgery, presurgical DWI of the brain rarely has been included to evaluate patients, despite its superiority in imaging abnormalities. Preoperative determination of existing cerebral ischemic lesions may help to assess the likelihood and etiology of postoperative neurologic complications. We performed cerebral DWI on consecutive patients before cardiac surgery to prospectively evaluate the incidence of ischemic lesions and to determine their relationship to postoperative neurocognitive function, stroke, and associated risk factors.


   Material and Methods
Top
 Abstract
 Introduction
 Material and Methods
Results
 Comment
 Acknowledgments
 References
 
Patients
We prospectively studied a series of consecutive patients who underwent elective cardiac surgery in Kumamoto Chuo Hospital from September 2004 to July 2007. Surgery included coronary artery grafting (CABG) with CPB (on pump) or without CPB (off pump), mitral valve repair or replacement, or aortic valve replacement. Exclusion criteria were a contraindication to MRI or inability to evaluate cognitive dysfunction and stroke. Contraindications for MRI were claustrophobia, an implanted pacemaker, and some metal prostheses. Demographic and preoperative data recorded in an institutional database included age, sex, hypertension, diabetes mellitus, hyperlipidemia, renal insufficiency (creatinine ≥ 1.9 mg/dL), peripheral vascular disease, abdominal aortic aneurysm, and history of atrial fibrillation, smoking, stroke, or transient ischemic attack. The hospital Institutional Review Board approved the present study, and all patients provided their informed consent to participate.

MRI Scans
We evaluated existing brain abnormalities and the presence of lesions on preoperative DWI scans. Magnetic resonance imaging and magnetic resonance angiography (MRA) were performed on all patients 1 to 7 days before cardiac surgery. The MRI examinations were made with a 1.5 Tesla system (Gyroscan Intera Achieva Nova Dual; Philips Medical Systems, Best, Netherlands). The imaging protocol included a diffusion-weighted, single-shot, spin echo echoplanar sequence (diffusion gradient b values of 0 and 1000 s/mm2, repetition time [TR] 3000 ms, echo time [TE] 51 ms, slice thickness 5 mm with a 1-mm intersection gap, matrix 112 x 256 pixels, 230-mm field of view), turbo fluid attenuated inversion recovery, and T2-weighted turbo spin echo sequences. For DWI, the diffusion gradients for total acquisition were successively and separately applied in three orthogonal directions for a total acquisition time of 30 s. Trace images were then generated and apparent diffusion coefficient maps calculated with a dedicated software tool. Magnetic resonance angiography included intracranial and neck vessels and was performed using a three-dimensional time-of-flight technique.

The MRI findings (fluid attenuated inversion recovery and T2) were classified as almost normal or leukoaraiosis; some small infarctions with a diameter of less than 15 mm; or multiple small infarctions or large infarctions greater than 15 mm or those that included the cortical area. The degree of stenosis of intracranial arteries was graded bilaterally by MRA as almost normal; moderate narrowing greater than 50%; or occluded [11]. The degree of stenosis in the carotid arteries was graded based on MRA as normal or mild narrowing of less than 50%; moderate narrowing of 50% to 75%; or severe narrowing greater than 75% or obstruction [12, 13].

The DWI scan results were considered abnormal if the scan revealed an area of hyperintensity on DWI and hypointensity on apparent diffusion coefficient maps relative to the normal brain, signifying cerebral ischemia. The lesions on MRI and MRA findings and the number, size, and location of recent ischemic lesions on DWI were evaluated by two experienced neuroradiologists masked to the clinical and neuropsychological data.

Neurologic Evaluation
Cognitive status was assessed by four tests administered preoperatively and 1 week after surgery to all patients when they were free of the effects of sedatives. The tests included the Hasegawa dementia score (HDS), the Kana pick-out test, the digit symbol substitution test, and the digit span test (forward and backward). The HDS is a modification of the Mini-Mental State Examination scored from 0 to 30, with higher scores representing a better cognitive state [14]. Preoperative cognitive impairment was defined as HDS less than 24 (equivalent to 24 on the Mini-Mental State Examination). The Kana pick-out test measures ability in the executive function of prefrontal lobe.

These tests were performed preoperatively by one of three trained investigators (T.B., T.G., or A.Y.) who were assigned randomly to patients. All tests were performed postoperatively by the same investigator (T.B), who was masked to treatment allocation. Postoperative cognitive dysfunction was defined as a decrease of least 20% from baseline in an individual's performance in more than two tests.

Postoperative brain MRI or CT was performed only on patients with neurologic deficits lasting more than 24 hours. Stroke was defined as new postoperative neurologic deficits that were confirmed by postoperative MRI or CT of the brain that were verified by neurologists.

Patient Management and Evaluation of Arteriosclerosis in the Aorta
Diazepam and fentanyl were used to induce and maintain anesthesia, supplemented with isoflurane or sevoflurane during surgery. Surgery with CPB was performed using a membrane oxygenator and roller pump under alpha-stat pH management and moderate hypothermia (28° to 34°C), as described previously [4]. Patients with prior cerebral infarction or severe carotid stenosis were maintained at a mean arterial pressure greater than 70 mm Hg during CPB and rewarmed to maintain no more than a 3°C difference between rectal and CPB perfusion temperatures. In other patients, mean arterial pressure was maintained between 50 and 70 mm Hg, and the difference between rectal and CPB perfuse temperature was restricted to 5° to 6°C during rewarming. Off-pump CABG surgery was performed with a Medtronic Octopus IV (Medtronic Inc, Minneapolis, MN). A deep pericardial traction suture was applied for cardiac displacement. A cell-saving device was used to conserve intraoperative blood.

All patients underwent epiaortic ultrasonography scans at the time of surgery to screen for atherosclerosis of the ascending aorta. We divided the ascending aorta from the aortic valve to the innominate artery into three segments and assessed intimal thickening off-line on videotape records, as described previously [15]. The degree of atherosclerosis in the ascending aorta was graded as almost normal or mild (< 3 mm intimal thickening); moderate (≥ 3 mm intimal thickening involving one segment of the ascending aorta); or severe (≥ 3 mm intimal thickening involving 2 or all 3 segments, often with protruding surface ulcerations or mobile components). All patients were assessed by one echocardiography technician. Based on the findings from real-time imaging, the need to modify cannulation, clamping, proximal graft anastomotic sites, or cardioplegia cannulation sites was determined by the cardiac surgeons.

Statistical Analysis
Patients were divided into two groups according to their degree of preoperative DWI abnormality: DWI absent (no abnormalities) and DWI present (with DWI abnormalities). From the results of previous studies [8–10], we postulated that early cardiac catheterization before cardiac surgery might significantly increase the incidence of DWI abnormalities. To determine whether there was a trend in relation to timing cardiac catheterization, we examined the rates of cardiac catheterization within 14 days before MRI scans. The choice of a cut-off at 14 days was based on a gradual increase in apparent diffusion coefficient to at or above normal, usually by 14 days [16]. Continuous variables are expressed as mean ± SD. Comparisons between the two groups were made with Student's t test for continuous variables and with the {chi} 2 or Fisher's exact test for categorical variables. A p value less than 0.05 was considered significant.


   Results
Top
 Abstract
 Introduction
 Material and Methods
 Results
Comment
 Acknowledgments
 References
 
From September 2004 to July 2007, 299 consecutive patients underwent elective cardiac surgery. From this total, 52 patients were excluded from the study, including 38 patients who were contraindicated for MRI; 8 patients who because of physical or mental status could not participate in neurologic testing; and 6 who had prolonged tracheal intubation (≥ 7 days) for pulmonary complications. All of the remaining 247 patients (82.6%) agreed to participate. There were 91 women and 156 men who ranged in age from 31 to 89 years (mean, 70 ± 9). The DWI was performed an average of 4 ± 2 days before cardiac surgery. Fourteen patients underwent DWI before cardiac catheterization; we excluded these 14 patients from the assessment of timing of cardiac catheterization.

Abnormalities were detected by DWI before cardiac surgery in 11 of the 247 patients (4.5%). The DWI present group had a more frequent history of cerebrovascular disease and a significant higher rate of cardiac catheterization within the 14 days before MRI scans (Table 1).


View this table:
[in this window]
[in a new window]

  		Table 1 Patient Characteristics With Imaging Results
 
Table 2 summarizes the lesion characteristics for the 11 patients in the DWI present group. Nine patients had a single lesion, and the other patients had 3 and 2 lesions. Lesions were small, averaging less than 7 mm, with a maximum diameter of 11 mm. There were 14 cerebral ischemic lesions, 13 in the left hemisphere and 1 in the right, with 86% found supratentorially. Most lesions (71%) were located in the white matter (corona radiate, internal capsule, subcortical frontal and temporal lobes).


View this table:
[in this window]
[in a new window]

  		Table 2 Clinical and Radiologic Characteristics of 11 Patients With Abnormalities on Diffusion-Weighted Magnetic Resonance Imaging (DWI)
 
Three of the 11 DWI patients (27%) had clinically apparent neurologic abnormalities before their cardiac surgery. One of these patients (patient 11, Table 2) with right hemiparesis had atrial fibrillation. Another 2 patients (patients 2 and 3; Table 2) had symptoms within a few minutes after cardiac catherization.

Of the 11 patients with DWI abnormalities, 5 had elective surgery delayed by 2 to 4 weeks (24 ± 7 days) and follow-up imaging studies. Of these 5 patients (patients 1 through 4 and 6; Table 2), 1 (patient 2; Table 2) demonstrated subsequent DWI abnormalities in the right corona radiate (2 lesions) whereas 4 showed no relevant ischemic lesions on preoperative follow-up studies. Postoperative CT or MRI was performed in 3 of 11 patients (27%; patients 2, 5, 9; Table 2). One DWI patient (patient 5, Table 2) had a small area with a diffusion abnormality that was larger on the postoperative MRI sequence, and he had dysarthria and right hemiparesis (Fig 1). This case was a 67-year-old man with a history of stroke, and carotid and intracranial artery stenosis. He had a cardiac catherization 5 days before the preoperative MRI scan without clinical signs. On the other hand, in the DWI absent group, postoperative CT or MRI was performed in 17 of 236 patients (7%). Of these 17 patients, postoperative DWI performed on 11 and revealed acute cerebral infarctions in 4 (36%); 2 patients had right hemiparesis and 2 patients had left hemiparesis.


Figure 1
View larger version (76K):
[in this window]
[in a new window]

  		Fig 1. Diffusion-weighted magnetic resonance imaging (MRI) of a 67-year-old man (patient 5, Table 2) without any demonstrable neurologic deficits before off-pump coronary artery bypass graft surgery. (A) The preoperative MRI scan revealed a small diffusion abnormality on the left posterior limb of the internal capsule. (B) Another scan performed 5 days after surgery demonstrated that the size of the diffusion restriction lesion had increased; the patient had dysarthria and right hemiparesis.

 
Table 3 lists the prevalence of intracranial and carotid artery stenosis, atherosclerosis of the ascending aorta, preoperative cognitive impairment, postoperative cognitive dysfunction, and stroke. The DWI present group had a significantly higher rate of cerebral infarction, carotid artery stenosis, and preoperative cognitive impairment before surgery. There was no statistical difference in postoperative cognitive dysfunction and stroke between the two groups.


View this table:
[in this window]
[in a new window]

  		Table 3 Prevalence of Intracranial and Carotid Artery Stenosis, Atherosclerosis of the Ascending Aorta, and Perioperative Neurologic Complications
 

   Comment
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
Acknowledgments
 References
 
This study demonstrated a 4.5% incidence of abnormalities identified by DWI in patients before cardiac surgery. The findings suggested that patients with abnormalities had more history of cerebrovascular disease, early surgery after cardiac catheterization, cerebral infarction, carotid artery stenosis, and preoperative cognitive impairment.

Recent studies with DWI have shown that new cerebral infarctions occurred in 31% to 47% of patients after cardiac surgery that used CPB [5–7]. These findings were made in the presence of methodologic limitations, including a failure to assess the rate of cerebral ischemic lesions before surgery. The importance of evaluating for new cerebral ischemic lesions preoperatively was emphasized by 1 patient who experienced an enlarged lesion that was revealed on the postoperative scan and appeared with a neurologic abnormality.

The pathogenesis of preexisting cerebral ischemic lesions is unknown. One possible mechanism is embolization. Recent studies suggest that asymptomatic embolic cerebral infarction may be detected in 2.2% to 22% of patients after left-side heart catheterization using DWI [8–10]. Left-side heart catheterization with coronary angiography or catheterization of cardiac valves is a standard procedure to evaluate patients before cardiac surgery. Lund and coworkers [8] reported that cerebral embolisms were observed frequently by transcranial Doppler ultrasound during left heart catheterization. Omran and associates [9] found a highly significant correlation between fluoroscopy time and cerebral lesions. Total fluoroscopy time represented the overall influence of catheter manipulation, which serves as a potential embolic source because plaques may be dislodged from the ascending aorta or the aortic arch. In addition, DWI is highly sensitive for detecting acute infracts within the first 14 days after they occur. Therefore, the apparent diffusion coefficient typically may remain depressed during the preoperative period. In fact, in the present study 10 of 11 patients (91%) with DWI abnormalities had left heart catheterization within 2 weeks before their cardiac surgery.

Other causes exist for embolism, transient ischemic attack, or minor ischemic stroke in the preoperative period. Recent studies of transient ischemic attack patients demonstrated that almost one half of patients had an abnormality that was detectable on DWI [17, 18]. Schulz and colleagues [19] reported that DWI found clinically appropriate ischemic lesions in 57% of minor stroke patients and 14% of transient ischemic attack patients that presented more than 2 weeks after a symptomatic event. It is known that the early risks of stroke after transient ischemic attack are substantially higher. In this study, the DWI present group had a significantly higher rate of preoperative cerebral infarctions and carotid artery stenosis. Additionally, cardiac procedures, particularly using CPB, are suspected to exacerbate neurologic deficits due to embolism, inflammatory response, and hypoperfusion. Cardiopulmonary bypass may aggravate existing neurologic ischemia and potentiate cerebral edema in areas where the blood brain barrier is disrupted. Patients with preoperative cerebral injury may be more vulnerable to the adverse effects of cardiac surgery. Therefore, we suggest that cardiac surgery is safer if it can be delayed for 2 to 3 weeks. Diffusion-weighted imaging may provide useful clinical information to determine the optimal timing of strategies to use in cardiac surgery.

Cognitive dysfunction after cardiac surgery has been the subject of many studies [20–22]. These studies have attempted to identify particular aspects of operative procedures that lead to dysfunction. In contrast, the preoperative cognitive status of patients experiencing dysfunction has been studied less well. Millar and coworkers [23] reported that 16% of patients performed poorly on the Stroop test, indicating impaired cognition before surgery. Hogue and colleagues [24] found cognitive impairment in 45% of female patients before their cardiac surgery. In the present study, the DWI present group had a significant decline in cognitive function before surgery compared with the DWI absent group. However, the correlation between the presence of abnormalities uncovered by DWI and cognitive impairment still is uncertain. Restrepo and colleagues [5] studied 13 patients and found that 4 with postoperative defects on DWI had a larger neurocognitive decline than did patients with normal DWI. Barber and coworkers [25] also reported that 43% of patients with postoperative DWI had new ischemic lesions, and cognitive decline was seen in all patients. In contrast, no such association was found in other studies of patients after cardiac surgery [6, 7, 26–28]. Further studies are needed to determine the relationship between DWI lesions and cognitive dysfunction.

There were several limitations to the present analysis. Our data were from a single institution. We can not exclude the possibility that our results were biased by institutional standards and patient population. In addition, postoperative DWI was not assessed in our patients, so the correlation between the presence of preoperative DWI abnormalities and postoperative new cerebral ischemic lesions is uncertain.

In conclusion, this study demonstrated that, from among 247 consecutive patients scheduled for cardiac surgery, 11 (4.5%) were identified by DWI to have existing abnormalities, including in patients without obvious neurologic deficits. These findings have important implications for our understanding of the etiology of postoperative neurologic complications and for protective strategies to reduce cerebral injury or improve cognitive dysfunction.


   Acknowledgments
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
References
 
The authors thank Dr Jon Moon for his editorial assistance.


   References
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
 References
 

  1. Roach GW, Kanchuger M, Mangano CM, et al. Adverse cerebral outcomes after coronary bypass surgery. Multicenter Study of Perioperative Ischemia Research Group and the Ischemia Research and Education Foundation Investigators. N Engl J Med 1996;335:1857-1863.[Abstract/Free Full Text]
  2. Tuman KJ, McCarthy RJ, Najafi H, Ivankovich AD. Differential effects of advanced age on neurologic and cardiac risks of coronary artery operations J Thorac Cardiovasc Surg 1992;104:1510-1517.[Abstract]
  3. McKhann GM, Goldsborough MA, Borowicz Jr LM, et al. Predictors of stroke risk in coronary artery bypass patients Ann Thorac Surg 1997;63:516-521.[Abstract/Free Full Text]
  4. Goto T, Baba T, Honma K, et al. Magnetic resonance imaging findings and postoperative neurologic dysfunction in elderly patients undergoing coronary artery bypass grafting Ann Thorac Surg 2001;72:137-142.[Abstract/Free Full Text]
  5. Restrepo L, Wityk RJ, Grega MA, et al. Diffusion- and perfusion-weighted magnetic resonance imaging of the brain before and after coronary artery bypass grafting surgery Stroke 2002;33:2909-2915.[Abstract/Free Full Text]
  6. Knipp SC, Matatko N, Schlamann M, et al. Small ischemic brain lesions after cardiac valve replacement detected by diffusion-weighted magnetic resonance imaging: relation to neurocognitive function Eur J Cardiothorac Surg 2005;28:88-96.[Abstract/Free Full Text]
  7. Stolz E, Gerriets T, Kluge A, Klovekorn WP, Kaps M, Bachmann G. Diffusion-weighted magnetic resonance imaging and neurobiochemical markers after aortic valve replacement: implications for future neuroprotective trials? Stroke 2004;35:888-892.[Abstract/Free Full Text]
  8. Lund C, Nes RB, Ugelstad TP, et al. Cerebral emboli during left heart catheterization may cause acute brain injury Eur Heart J 2005;26:1269-1275.[Abstract/Free Full Text]
  9. Omran H, Schmidt H, Hackenbroch M, et al. Silent and apparent cerebral embolism after retrograde catheterisation of the aortic valve in valvular stenosis: a prospective, randomized study Lancet 2003;361:1241-1246.[Medline]
  10. Hamon M, Gomes S, Oppenheim C, et al. Cerebral microembolism during cardiac catheterization and risk of acute brain injury: a prospective diffusion-weighted magnetic resonance imaging study Stroke 2006;37:2035-2038.[Abstract/Free Full Text]
  11. Heiserman JE, Drayer BP, Keller PJ, Fram EK. Intracranial vascular stenosis and occlusion: evaluation with three-dimensional time-of-flight MR angiography Radiology 1992;185:667-673.[Abstract/Free Full Text]
  12. Atlas SW. MR angiography in neurologic disease Radiology 1994;193:1-16.[Abstract/Free Full Text]
  13. Masaryk TJ, Lewin JS, Laub G. Magnetic resonance angiographyIn: Stark DD, Bradley WG, editors. Magnetic resonance imaging. 2nd ed.. St.Louis: Mosby Year Book; 1992. pp. 299-334.
  14. Hasegawa K, Inoue K, Moriya K. An investigation of dementia rating scale for the elderly Seishin Igaku (Tokyo) 1974;16:965-969.
  15. Goto T, Baba T, Matsuyama K, Honma K, Ura M, Koshiji T. Aortic atherosclerosis and postoperative neurological dysfunction in elderly coronary surgical patients Ann Thorac Surg 2003;75:1912-1918.[Abstract/Free Full Text]
  16. Burdette JH, Ricci PE, Petitti N, Elster AD. Cerebral infarction: time course of signal intensity changes on diffusion-weighted MR images AJR Am J Roentgenol 1998;171:791-795.[Abstract/Free Full Text]
  17. Kidwell CS, Alger JR, Di Salle F, et al. Diffusion MRI in patients with transient ischemic attacks Stroke 1999;30:1174-1180.[Abstract/Free Full Text]
  18. Rovira A, Rovira-Gols A, Pedraza S, Grive E, Molina C, Alvarez-Sabin J. Diffusion-weighted MR imaging in the acute phase of transient ischemic attacks AJNR Am J Neuroradiol 2002;23:77-83.[Abstract/Free Full Text]
  19. Schulz UG, Briley D, Meagher T, Molyneux A, Rothwell PM. Abnormalities on diffusion weighted magnetic resonance imaging performed several weeks after a minor stroke or transient ischaemic attack J Neurol Neurosurg Psychiatry 2003;74:734-738.[Abstract/Free Full Text]
  20. Shaw PJ, Bates D, Cartlidge NE, et al. Neurologic and neuropsychological morbidity following major surgery: comparison of coronary artery bypass and peripheral vascular surgery Stroke 1987;18:700-707.[Abstract/Free Full Text]
  21. Murkin JM, Martzke JS, Buchan AM, Bentley C, Wong CJ. A randomized study of the influence of perfusion technique and pH management strategy in 316 patients undergoing coronary artery bypass surgery. II. Neurologic and cognitive outcomes J Thorac Cardiovasc Surg 1995;110:349-362.[Abstract/Free Full Text]
  22. Newman MF, Kirchner JL, Phillips-Bute B, et al. Neurological Outcome Research Group and the Cardiothoracic Anesthesiology Research Endeavors Investigators Longitudinal assessment of neurocognitive function after coronary-artery bypass surgery N Engl J Med 2001;344:395-402.[Abstract/Free Full Text]
  23. Millar K, Asbury AJ, Murray GD. Pre-existing cognitive impairment as a factor influencing outcome after cardiac surgery Br J Anaesth 2001;86:63-67.[Abstract/Free Full Text]
  24. Hogue Jr CW, Hershey T, Dixon D, et al. Preexisting cognitive impairment in women before cardiac surgery and its relationship with C-reactive protein concentrations Anesth Analg 2006;102:1602-1608.[Abstract/Free Full Text]
  25. Barber PA, Hach S, Tippett LJ, Ross L, Merry AF, Milsom P. Cerebral ischemic lesions on diffusion-weighted imaging are associated with neurocognitive decline after cardiac surgery Stroke 2008;39:1427-1433.[Abstract/Free Full Text]
  26. Bendszus M, Reents W, Franke D, et al. Brain damage after coronary artery bypass grafting Arch Neurol 2002;59:1090-1095.[Abstract/Free Full Text]
  27. Friday G, Sutter F, Curtin A, et al. Brain magnetic resonance imaging abnormalities following off-pump cardiac surgery Heart Surg Forum 2005;8:E105-E109.[Medline]
  28. Cook DJ, Huston III J, Trenerry MR, Brown Jr RD, Zehr KJ, Sundt III TM. Postcardiac surgical cognitive impairment in the aged using diffusion-weighted magnetic resonance imaging Ann Thorac Surg 2007;83:1389-1395.[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 HeartHome page
N Stroobant and G Vingerhoets
Pre-existing cognitive impairment in candidates for cardiac surgery: an overview
Heart, November 15, 2009; 95(22): 1820 - 1825.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
R. Gottesman and C. W. Hogue
Invited Commentary
Ann. Thorac. Surg., November 1, 2008; 86(5): 1569 - 1569.
[Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Takaaki Koshiji
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Maekawa, K.
Right arrow Articles by Koshiji, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Maekawa, K.
Right arrow Articles by Koshiji, T.
Related Collections
Right arrow Cerebral protection

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ANN THORAC SURG ASIAN CARDIOVASC THORAC ANN EUR J CARDIOTHORAC SURG
J THORAC CARDIOVASC SURG ICVTS ALL CTSNet JOURNALS