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  • Author or Editor: Akira Ogawa x
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Kenji Yoshida, Kuniaki Ogasawara, Masakazu Kobayashi, Junichi Tsuboi, Hitoshi Okabayashi and Akira Ogawa

Object

Scar formation in the carotid sheath is often identified during carotid endarterectomy (CEA) in patients with previous cardiac surgery, and dissection of the carotid sheath and exposure of the carotid arteries in such patients are difficult. The purpose of the present study was to investigate factors related to scar formation identified during CEA in patients with previous cardiac surgery.

Methods

Twenty-three patients with internal carotid artery stenosis (≥ 70%) and previous cardiac surgery underwent CEA. A patient was prospectively defined as having scar formation during CEA when scissors were required throughout dissection of the carotid sheath and exposure of the carotid arteries.

Results

Scar formation was identified during dissection of the carotid sheath in 7 patients (30.4%). In all 7 patients, the side of CEA was identical to the side on which the Swan-Ganz catheter was inserted during cardiac surgery, and the incidence of previous ipsilateral Swan-Ganz catheter insertion was significantly higher in patients with the scar formation (100%) than in those without (31.3%). Seven (58.3%) of 12 patients with a history of ipsilateral Swan-Ganz catheter insertion had scar formation. Two of the 7 patients with scar formation experienced complications after CEA, including one patient with hemiparesis due to artery-to-artery embolism during surgery, and another patient with transient vocal cord paralysis.

Conclusions

A history of Swan-Ganz catheter insertion during previous cardiac surgery is associated with the presence of scar tissue in the ipsilateral carotid sheath and a higher risk of complications during CEA.

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Kuniaki Ogasawara, Keiko Yamadate, Masakazu Kobayashi, Hidehiko Endo, Takeshi Fukuda, Kenji Yoshida, Kazunori Terasaki, Takashi Inoue and Akira Ogawa

Object. Cognitive impairment occurs in 20 to 30% of patients following carotid endarterectomy (CEA). The purpose of the present study was to determine whether postoperative cerebral hyperperfusion is associated with impairment of cognitive function in patients undergoing that procedure.

Methods. Cerebral blood flow (CBF) was measured using single-photon emission computerized tomography scanning before and immediately after CEA and on the 3rd postoperative day in 92 patients with ipsilateral internal carotid artery stenosis of 70% or greater. Hyperperfusion post-CEA was defined as a 100% increase or greater in CBF compared with preoperative values. Neuropsychological testing was also performed preoperatively and at the 1-, 3-, and 6-month follow-up examinations.

At the 1-month postoperative neuropsychological assessment, 11 patients (12%) displayed evidence of cognitive impairment. In addition, the incidence of postoperative cognitive impairment in patients with post-CEA hyperperfusion (seven [58%] of 12 patients) was significantly higher than that in patients without post-CEA hyperperfusion (four [5%] of 80 patients; p < 0.0001). A logistic regression analysis demonstrated that post-CEA hyperperfusion was the only significant independent predictor of postoperative cognitive impairment. Of the seven patients in whom post-CEA hyperperfusion and cognitive impairment were identified 1 month postoperatively, four (including three patients with hyperperfusion syndrome) remained cognitively impaired at the 3- and 6-month follow-up examinations.

Conclusions. Postoperative cerebral hyperperfusion is associated with impairment of cognitive function in patients undergoing CEA. Furthermore, the development of hyperperfusion syndrome is associated with the persistence of postoperative cognitive impairment.

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Kuniaki Ogasawara, Hirotsugu Yukawa, Masakazu Kobayashi, Chiaki Mikami, Hiromu Konno, Kazunori Terasaki, Takashi Inoue and Akira Ogawa

Object. The purpose of this study was to determine whether the preoperative measurement of acetazolamide-induced changes in cerebral blood flow (CBF), which is performed using single-photon emission computerized tomography (SPECT) scanning, can be used to identify patients at risk for hyperperfusion following carotid endarterectomy (CEA). In addition, the authors investigated whether monitoring of CBF with SPECT scanning after CEA can be used to identify patients at risk for hyperperfusion syndrome.

Methods. Cerebral blood flow and cerebrovascular reactivity (CVR) to acetazolamide were measured before CEA in 51 patients with ipsilateral internal carotid artery stenosis (≥ 70% stenosis). Cerebral blood flow was also measured immediately after CEA and on the 3rd postoperative day.

Hyperperfusion (an increase in CBF of ≥ 100% compared with preoperative values) was observed immediately after CEA in eight of 12 patients with reduced preoperative CVR. Reduced preoperative CVR was the only significant independent predictor of post-CEA hyperperfusion. Forty-three patients in whom hyperperfusion was not detected immediately after CEA did not exhibit hyperperfusion on the 3rd postoperative day and did not experience hyperperfusion syndrome. In two of eight patients in whom hyperperfusion occurred immediately after CEA, CBF progressively increased and hyperperfusion syndrome developed, but intracerebral hemorrhage did not occur. In the remaining six of eight patients in whom hyperperfusion was detected immediately after CEA, the CBF progressively decreased and the hyperperfusion resolved by the 3rd postoperative day.

Conclusions. Preoperative measurement of acetazolamide-induced changes in CBF, which is performed using SPECT scanning, can be used to identify patients at risk for hyperperfusion after CEA. In addition, post-CEA monitoring of CBF performed using SPECT scanning results in the timely and reliable identification of patients at risk for hyperperfusion syndrome.

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Shunsuke Kakino, Kuniaki Ogasawara, Yoshitaka Kubo, Hiroshi Kashimura, Hiromu Konno, Atsushi Sugawara, Masakazu Kobayashi, Makoto Sasaki and Akira Ogawa

Object

Although angioplasty and stent placement for vertebral artery (VA)–origin stenosis have been performed using endovascular techniques, a high likelihood of restenosis has been observed in the long term. Therefore, the authors assessed the long-term clinical and angiographic outcomes in patients after VA–subclavian artery (SA) transposition.

Methods

Thirty-six patients (31 men, 5 women; mean age 64.3 years, range 46–76 years) underwent clinical evaluation (modified Rankin Scale [mRS]) and cervical angiographic evaluation preoperatively and within 1 month of and 6 months after VA-SA transposition undertaken to treat symptomatic stenosis of VA origin.

Results

Postoperative neurological deficits due to intraoperative brain ischemia did not occur, and MR imaging demonstrated no new postoperative ischemic lesions in any of the patients. One patient died of acute myocardial infarction 2 months after surgery and another developed a left thalamic hemorrhage (mRS score of 5) at 42 months postsurgery. None of the remaining 34 patients experienced further ischemic events, and the mRS score in all of these patients remained unchanged during a mean follow-up period of 54 months. The degree of VA-origin stenosis (preoperative mean 84%) was reduced to ≤ 30% after surgery (mean 2%). Long-term follow-up angiography in 29 patients (81%) revealed the absence of restenosis, defined as > 50% luminal narrowing, in all of them.

Conclusions

The clinical and angiographic long-term outcomes demonstrated here suggest that VA-SA transposition will be useful in patients with symptomatic stenosis of VA origin.

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Ryounoshin Hirooka, Kuniaki Ogasawara, Makoto Sasaki, Keiko Yamadate, Masakazu Kobayashi, Yasunori Suga, Kenji Yoshida, Yasunari Otawara, Takashi Inoue and Akira Ogawa

Object

Cerebral hyperperfusion after carotid endarterectomy (CEA) impairs cognitive function and is often detected on cerebral blood flow (CBF) imaging. The purpose of the present study is to investigate structural brain damage seen on magnetic resonance (MR) images obtained in patients with cerebral hyperperfusion and cognitive impairment after CEA.

Methods

One hundred and fifty-eight patients with ipsilateral internal carotid artery stenosis (≥ 70%) underwent CEA. Neuropsychological testing was performed preoperatively and at the 1st postoperative month. Cerebral blood flow was measured using single-photon emission computed tomography before, immediately after, and 3 days after surgery. Magnetic resonance imaging was performed before and 1 day after surgery. In patients with post-CEA hyperper-fusion (defined as a CBF increase ≥ 100% compared with preoperative values) on CBF imaging, MR images were also obtained on the 3rd postoperative day, the day on which hyperperfusion syndrome developed, and 1 month after the operation.

Results

The incidence of postoperative cognitive impairment was significantly higher in patients with post-CEA hyperperfusion on CBF imaging (12 [75%] of 16 patients) than in those without (6 [4%] of 142 patients; p < 0.0001). Only 1 of 5 patients with cerebral hyperperfusion syndrome developed reversible brain edema in the cerebral hemisphere ipsilateral to the CEA on MR images obtained on the day hyperperfusion syndrome occurred. However, postoperative cognitive impairment developed in all 5 patients with cerebral hyperperfusion syndrome regardless of the presence or absence of new lesions on MR images. In addition, postoperative cognitive impairment developed in 5 (45%) of 11 patients with asymptomatic cerebral hyperperfusion on CBF imaging despite the absence of new lesions on any postoperative MR images.

Conclusions

Although cerebral hyperperfusion syndrome after CEA sometimes results in reversible brain edema visible on MR imaging, postoperative cerebral hyperperfusion—even when asymptomatic—often results in impaired cognitive function without structural brain damage on MR imaging.

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Taro Suzuki, Kuniaki Ogasawara, Ryonoshin Hirooka, Makoto Sasaki, Masakazu Kobayashi, Daiya Ishigaki, Shunro Fujiwara, Kenji Yoshida, Yasunari Otawara and Akira Ogawa

Object

Preoperative impairment of cerebral hemodynamics predicts the development of new cerebral ischemic events after carotid endarterectomy (CEA), including neurological deficits and cerebral ischemic lesions on diffusion weighted MR imaging. Furthermore, the signal intensity of the middle cerebral artery (MCA) on single-slab 3D time-of-flight MR angiography (MRA) can assess hemodynamic impairment in the cerebral hemisphere. The purpose of the present study was to determine whether, on preoperative MR angiography, the signal intensity of the MCA can be used to identify patients at risk for development of cerebral ischemic events after CEA.

Methods

The signal intensity of the MCA ipsilateral to CEA on preoperative MR angiography was graded according to the ability to visualize the MCA in 106 patients with unilateral internal carotid artery stenosis (≥ 70%). Diffusion weighted MR imaging was performed within 3 days of and 24 hours after surgery. The presence or absence of new postoperative neurological deficits was also evaluated.

Results

Cerebral ischemic events after CEA were observed in 16 patients. Reduced signal intensity of the MCA on preoperative MR angiography was the only significant independent predictor of postoperative cerebral ischemic events. When the reduced MCA signal intensity on preoperative MR angiography was defined as an impairment in cerebral hemodynamics, MR angiography grading resulted in an 88% sensitivity and 63% specificity, with a 30% positive- and a 97% negative-predictive value for the development of postoperative cerebral ischemic events.

Conclusions

Signal intensity of the MCA on preoperative single-slab 3D time-of-flight MR angiography is useful for identifying patients at risk for cerebral ischemic events after CEA.

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Koji Yoshida, Kuniaki Ogasawara, Hiroaki Saura, Hideo Saito, Masakazu Kobayashi, Kenji Yoshida, Kazunori Terasaki, Shunrou Fujiwara and Akira Ogawa

OBJECT

Cognitive function is often improved or impaired after carotid endarterectomy (CEA) for patients with cerebral hemodynamic impairment. Cerebral glucose metabolism measured using positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) correlates with cognitive function in patients with neurodegenerative diseases. The present study aimed to determine whether postoperative changes in cerebral glucose metabolism are associated with cognitive changes after CEA.

METHODS

In patients who were scheduled to undergo CEA for ipsilateral internal carotid artery (ICA) stenosis (≥ 70% narrowing), cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) to acetazolamide were assessed preoperatively using brain perfusion single-photon emission computed tomography (SPECT). CBF measurement using SPECT was also performed immediately after CEA. For patients with reduced preoperative CVR to acetazolamide in the cerebral hemisphere ipsilateral to surgery, cerebral glucose metabolism was assessed using FDG-PET before surgery and 3 months after surgery and was analyzed using 3D stereotactic surface projection. Neuropsychological testing was also performed preoperatively and 3 months postoperatively.

RESULTS

Twenty-two patients with reduced preoperative CVR to acetazolamide successfully underwent FDG-PET studies and neuropsychological testing before and after CEA. Seven, 9, and 6 patients were defined as showing improved, unchanged, and impaired postoperative cognition, respectively, based on the neuropsychological assessments. The cortical area with increased postoperative glucose metabolism was greater in patients with improved postoperative cognition than in those with unchanged (p < 0.001) or impaired (p < 0.001) postoperative cognition. The cortical area with decreased postoperative glucose metabolism was greater in patients with impaired postoperative cognition than in those with improved (p < 0.001) or unchanged (p < 0.001) postoperative cognition. All 7 patients with improved cognition exhibited postoperative hemispheric increases in glucose metabolism, while 5 of the 6 patients with impaired cognition exhibited postoperative hemispheric decreases in glucose metabolism. Brain perfusion SPECT revealed that the latter 6 patients experienced postoperative cerebral hyperperfusion, and 2 of the 6 patients exhibited cerebral hyperperfusion syndrome. The cortical area with decreased postoperative glucose metabolism in these 2 patients was greater than that in other patients.

CONCLUSIONS

Postoperative changes in cerebral glucose metabolism, as measured using FDG-PET, are associated with cognitive improvement and impairment after CEA.