Postoperative Hyperperfusion Syndrome Research Articles

Staged angioplasty in 2 patients with severe carotid artery stenosis: A case report and literature review

Rationale: Cerebral infarction is a common ischemic cerebrovascular disease, associated with high rates of morbidity, disability, and recurrence, that can seriously affect patient physical and mental health, as well as quality of life. Carotid artery stenosis is an independent risk factor of cerebral infarction. Following rapid developments in interventional technology and materials science, carotid artery stenting has arisen an important treatment option for carotid artery stenosis. However, surgery is associated with complications, such as postoperative hyperperfusion syndrome, which poses a serious threat to the life and health of patients. Staged angioplasty (SAP), that is, one-time revascularization of the carotid artery stenting, is divided into 2 stages. This method reduces the occurrence of hyperperfusion syndrome after stenting by increasing the ipsilateral cerebral blood flow in stages and gradually increasing the cerebral perfusion pressure. Patient concerns: Herein, we present 2 cases of elderly patients with severe carotid artery stenosis who underwent SAP to prevent hyperperfusion syndrome. Diagnoses: The final diagnosis was based on cervical vascular color Doppler ultrasonography, cervical vascular magnetic resonance angiography, and cerebral vascular digital subtraction angiography. Intervention: Both patients with severe carotid artery stenosis underwent a staged intravascular intervention. Outcomes: Both patients were followed up for 1 year, with neither developing any new cerebral infarction or recurrent stent restenosis. Lessons: When treating SAP, it is crucial to consider that patients with unstable carotid plaques may not be suitable for staging. Additionally, during phase II carotid stenting, it is important to assess any changes in the arterial morphology and select the appropriate device accordingly.

Predicting impaired cerebrovascular reactivity and risk of hyperperfusion syndrome in carotid artery stenosis using BeamSAT magnetic resonance imaging

Pencil-beam presaturation (BeamSAT) magnetic resonance imaging (MRI) produces selective magnetic resonance angiography (MRA) images of specific arteries, including the unilateral internal carotid artery (ICA-selective MRA) or vertebral artery (VA-selective MRA). We evaluate the influence of flow pattern, visualized using BeamSAT MRI, on preoperative cerebral hemodynamic status and postoperative hyperperfusion syndrome (HPS). Patients undergoing carotid artery stenting or carotid endarterectomy were categorized into two groups to evaluate flow pattern. Patients with neither crossflow on BeamSAT MRI nor mismatch in middle cerebral artery (MCA) signal intensity between ICA-selective and conventional MRA were classified into Group I, comprising 29 patients. Group II included all other patients comprising 19 patients, who were suspected of experiencing changes in intracranial flow patterns. Cerebral blood flow and cerebrovascular reactivity (CVR) were assessed using single-photon emission computed tomography, and potential HPS symptoms were retrospectively assessed by chart review. Preoperative ipsilateral CVR was significantly lower in Group II than in Group I (18.0% ± 20.0% vs. 48.3% ± 19.5%; P < 0.0001). Group II showed significantly impaired CVR (odds ratio 17.7, 95% confidence interval 1.82–171; P = 0.013) in multivariate analysis. The partial areas under the curve of the BeamSAT logistic model (0.843) were significantly larger than those of the conventional logistic model (0.626) over the range of high sensitivity (0.6–1) (P = 0.04). The incidence of postoperative HPS symptoms was significantly higher in Group II than in Group I (8/19 vs. 1/29; P = 0.001). BeamSAT MRI may be a valuable and non-invasive tool for assessing cerebral hemodynamics and predicting postoperative HPS.

Redefining postoperative hypertension management in carotid surgery: a comprehensive analysis of blood pressure homeostasis and hyperperfusion syndrome in unilateral vs. bilateral carotid surgeries and implications for clinical practice.

This study evaluates the implications of blood pressure homeostasis in bilateral vs. unilateral carotid surgeries, focusing on the incidence of postoperative hypertension, hyperperfusion syndrome, and stroke as primary outcomes. It further delves into the secondary outcomes encompassing major adverse cardiovascular events and all-cause mortality. Spanning two decades (2002-2023), this comprehensive retrospective research encompasses 15,369 carotid referrals, out of which 1,230 underwent carotid interventions. A subset of 690 patients received open carotid procedures, with a 10-year follow-up, comprising 599 unilateral and 91 bilateral surgeries. The Society for Vascular Surgery Carotid Reporting Standards underpin our methodological approach for data collection. Both univariate and multivariate analyses were utilized to identify factors associated with postoperative hypertension using the Statistical Package for the Social Sciences (SPSS) Version 22 (SPSS®, IBM® Corp., Armonk, N.Y., USA). A marked acute elevation in blood pressure was observed in patients undergoing both unilateral and bilateral carotid surgeries (p < 0.001). Smoking (OR: 1.183, p = 0.007), hyperfibrinogenemia (OR: 0.834, p = 0.004), emergency admission (OR: 1.192, p = 0.005), severe ipsilateral carotid stenosis (OR: 1.501, p = 0.022), and prior ipsilateral interventions (OR: 1.722, p = 0.003) emerged as significant factors that correlates with postoperative hypertension in unilateral surgeries. Conversely, in bilateral procedures, gender, emergency admissions (p = 0.012), and plaque morphology (p = 0.035) significantly influenced postoperative hypertension. Notably, 2.2% of bilateral surgery patients developed hyperperfusion syndrome, culminating in hemorrhagic stroke within 30 days. Intriguingly, postoperative stage II hypertension was identified as an independent predictor of neurological deficits post-secondary procedure in bilateral CEA cases (p = 0.004), attributable to hyperperfusion syndrome. However, it did not independently predict myocardial infarction or mortality outcomes. The overall 30-day stroke rate stood at 0.90%. Lowest incidence of post operative hypertension or any complications were observed in eversion carotid endartrertomy. The study identifies postoperative hypertension as a crucial independent predictor of perioperative stroke following bilateral carotid surgery. Moreover, the study elucidates the significant impact of bilateral CEA on the development of post-operative hyperperfusion syndrome or stroke, as compared to unilateral CEA. Currently almost 90% of our carotid practice is eversion carotid endartrerectomy.

Waveform Analysis of Superficial Temporal Artery-Middle Cerebral Artery Bypass Graft in Revascularization Surgery for Moyamoya Disease

Introduction: Postoperative hyperperfusion syndrome (PHS) is a well-known complication following superficial temporal artery (STA)-middle cerebral artery (MCA) bypass for moyamoya disease (MMD). The early detection of postoperative radiological hyperperfusion (PRH), characterized by a transient increase in local cerebral blood flow (CBF), is crucial for the early diagnosis of PHS. This study aimed to investigate the effectiveness of waveform analysis for early PRH detection. Methods: We reviewed 52 consecutive patients who underwent STA-MCA bypass for MMD. Patients were divided into PRH and non-PRH groups based on the postoperative/preoperative CBF ratio. We collected the intraoperative bypass graft waveform and bypass flow data using a flowmeter. The pulsatile index (PI), an indicator of peripheral vascular resistance (PVR), was calculated from bypass flow data. Next, the newly proposed index of PVR, the ratio of the time from peak to 50% decay and to 100% decay (RT50), was calculated through waveform analysis. The values were then compared between the PRH and non-PRH groups. Results: Twenty-seven of the 52 patients met the inclusion criteria. Fourteen of these 27 patients showed PRH. The RT50, but not the PI, was significantly higher in the PRH group. Linear regression analysis revealed a significant correlation between the RT50 and PI. In the receiver operating characteristic for predicting PRH, the area under the curve of RT50 was 0.750, with a cutoff value of 0.255, a sensitivity of 0.928, and a specificity of 0.500. Conclusion: The RT50 obtained from waveform analysis is associated with PVR and can be useful for the early detection of PRH in patients with MMD.

Inhalational Anesthesia Reduced Transient Neurological Events After Revascularization Surgery for Moyamoya Disease

BACKGROUND AND OBJECTIVES: The choice between inhalational and total intravenous anesthesia (TIVA) in revascularization surgery for Moyamoya disease (MMD) remains a topic of debate. Anesthesia methods have changed with the advent of new anesthetics. This study investigated whether modern anesthesia methods affected the development of neurological symptoms after revascularization surgery for MMD. METHODS: This single-center retrospective study included 63 adult patients (82 hemispheres) with MMD treated with direct and indirect bypass surgeries at our hospital between 2013 and 2022. Patients were divided into inhalational anesthesia (IA) and TIVA groups based on the anesthesia maintenance method. Baseline patient characteristics; postoperative neurological symptoms, including hyperperfusion syndrome, cerebral infarction, and transient neurological events (TNEs); and cortical hyperintensity belt (CHB) sign scores (5-point scale from 0 to 4) on postoperative magnetic resonance imaging were compared between the two groups. The operation methods, anesthetics, and intraoperative hemodynamic and ventilatory parameters were compared between patients with and without TNEs. RESULTS: The IA and TIVA groups comprised 39 and 43 hemispheres, respectively. The frequency of postoperative hyperperfusion syndrome and cerebral infarction did not differ between the groups, but the number of TNEs in the IA group (5/39; 13%) was significantly lower than that in the TIVA group (16/43; 37%). Multivariate logistic regression analysis revealed that TNEs were associated with TIVA (odds ratio, 3.91; 95% CI, 1.24-12.35; P = .02). The median [IQR] postoperative CHB sign score in the IA group (2 [1-3]) was significantly lower than that in the TIVA group (4 [3-4]). CONCLUSION: The IA group had fewer postoperative TNEs and lower CHB sign scores than the TIVA group. Although further studies are needed, this study provides insights into the prevention of TNEs with IA and reconsideration of the optimal anesthesia for MMD.

Combination of intraoperative indocyanine green video-angiography FLOW 800 and computed tomography perfusion to assess the risk of cerebral hyperperfusion syndrome in chronic internal carotid artery occlusion patients after revascularization surgery.

To study the changes of corticocerebral hemodynamics in surgical area and postoperative hyperperfusion syndrome in patients with chronic internal carotid artery occlusion (CICAO) by intraoperative indocyanine green videoangiography (ICGA)-FLOW 800 and CT perfusion after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery. From October 2019 to January 2021, 77 patients diagnosed with CICAO underwent direct bypass surgery at Huadong hospital (affiliated with Fudan University) were enrolled. Regions of interest (ROIs) at STA, proximal MCA (PMCA), distal MCA (DMCA), cortical blood capillary (CBC), and cortical vein (CV) were identified after anastomosis by ICGV-FLOW 800 including peak fluorescence intensity (PFI), time to peak (TTP), and area under the time curve (AUC) of fluorescence intensity. All patients underwent perfusion-weighted CT before bypass surgery and those patients with HPS were verified by CTP after bypass. 14 patients with HPS were verified by perfusion-weighted CT after bypass. In HPS group, the AUCTTP of DMCA was significantly larger (T = -3.301, p = 0.004) and TTP of CBC was shorter (T = -2.929, p = 0.005) than patients in non-HPS group. The larger AUCTTP of DMCA (OR = 3.024, 95%CI 1.390-6.578, p = 0.0050) was an independent risk factor by further multivariate logistic regression analysis. The hemodynamic changes of cortical vessels during STA-MCA bypass surgery could be recorded accurately by ICGV-FLOW 800. Furthermore, the increased AUCTTP of DMCA and shorter TTP of CBC may be potential risk factors of HPS.

A Novel Staged Revascularization Strategy for Bilateral Severe Internal Carotid Artery Stenosis at High Risk for Hyperperfusion Syndrome

Since bilateral severe internal carotid artery stenosis often is associated with severely decreased cerebrovascular reactivity (CVR) due to poor collateral blood flow, revascularization carries a high risk for development of hyperperfusion syndrome. In this study, we report a new staged strategy to prevent postoperative hyperperfusion syndrome in such patients. Bilateral severe cervical internal carotid artery stenosis patients with decreased CVR to 10% or less on one side were prospectively enrolled in this study. We first performed carotid artery stenting on the side with the milder CVR decrease (lower-risk side), aiming to improve hemodynamics associated with the severe CVR decrease on the greater-risk side. Then, carotid endarterectomy or carotid artery stenting was performed on the contralateral side after an interval of 4-8 weeks. In all 3 cases enrolled in this study, CVR on the greater-risk side improved to 10% or more 1 month after the first treatment. The ratio of regional cerebral blood flow on the contralateral greater-risk side was 114% 1 day after the second treatment, and HPS did not develop in any of the cases. Our treatment strategy, in which revascularization on the lower-risk side precedes that on the greater-risk side, is effective for the prevention of HPS in bilateral ICA stenosis patients.

Matching Selection of Donor-Recipient Vessels in Revascularization Surgery Effectively Reduce the Incidence of Postoperative Hyperperfusion Syndrome in Adult Moyamoya Disease: A Retrospective Comparison Study

Introduction: Cerebral hyperperfusion syndrome (CHS) is one of the most serious complications after revascularization surgery in patients with moyamoya disease (MMD). However, there are few effective measures to prevent the occurrence of CHS. Objective: The present study aims to examine the effect of the method about matching selection of donor-recipient vessels during revascularization surgery on the incidence of postoperative CHS in adult MMD patients. Methods: 216 Chinese adult patients with MMD received surgery treatment between January 2018 and December 2019 in our hospital were enrolled in this study. 191 out of 216 patients were included in this study. Matching selection method was defined as follows: (1) blood flow: the direction of blood flow and speed of the donor artery and potential receptor arteries were measured by flow 800 indocyanine green video angiography; (2) vascular diameter: the diameters of the donor artery and potential receptor arteries by a miniature ruler. Only the artery with antegrade flow and with smallest difference in flow speed and diameter with the donor artery will be selected as the receptor artery to perform anastomosis. Matching selection was performed from January 2019. Digital subtraction angiography was performed in all patients for initial MMD diagnosis. Perioperative cerebral perfusion and related clinical symptoms were monitored. Clinical characteristics, contralateral progression, and risk factors were reviewed. The incidence of CHS and the correlation of CHS with baseline characteristics or clinical conditions were analyzed. Results: Of these 191 patients, 82 patients received matching selection of donor-recipient vessels during revascularization surgery and 109 patients without. The postoperative CHS incidence in the matching group was 3.66%, which was much lower than that in the nonmatching group (15.60%). Multivariate analysis did not reveal a significant risk factor between the progression group and the nonprogression group. Correlation analysis revealed only the matching selection method was significantly associated with the reduced postoperative CHS incidence in MMD patients. Conclusions: The matching selection of donor-recipient vessels during revascularization surgery effectively reduces the incidence of postoperative CHS in adult patients with MMD.

Abstract TP129: Intraoperative Prediction of Cerebral Hyperperfusion Syndrome After STA-MCA Bypass Surgery by a Newly Developed Hyperspectral Imaging System

Background: Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass is the important treatment of moyamoya disease and other cerebral ischemic situations. However, cerebral hyperperfusion syndrome (HPS) may occur after vascular reconstructive surgery including STA-MCA bypass. 123 I-IMP-SPECT is useful to diagnose HPS after surgery, but there is no intraoperative device to predict HPS. Using intraoperative hyperspectral imaging data captured by hyperspectral camera (HSC), we can get the oxygen saturation value (SO2) of brain surface during surgery. We may predict HPS by analyzing intraoperative cerebral cortex SO2. Objective: To investigate whether the data from HSC during surgery is useful for prediction of postoperative HPS. Methods: 10 consecutive patients performed STA-MCA bypass were collected hyperspectral images of cerebral cortex by HSC before and after bypass. We got the SO2 data and analyzed the rate of change and correlation with HPS. Results: 3 patients presented temporary neurological deterioration several days after surgery and 123 I-IMP SPECT revealed focal intense increase in CBF at the sites of anastomosis. In these HPS patients, the rate of change of SO2 of cerebral cortex before and after bypass significantly increased in comparison with the patients didn’t present HPS (1.524 vs 1.089, P=0.0017). The receiver operating characteristic curve reveals if the rate of change of SO2 is more than 1.17, postoperative HPS is likely to occur (sensitivity=83%, AUC=0.81). Conclusions: Using the HSC, we may predict the occurrence of HPS after STA-MCA bypass. HSC can be the useful device in postoperative treatment for prevention of HPS.

Rapid evacuation of chronic subdural hematoma – A possible traumatic brain injury (TBI)

The chronic subdural hematoma is an entity, which affects mainly the elderly patients. According to literature, the complication rate was up to 22,7%, including recurrence of hematoma, worsening of the neurological status, postoperative delirium, etc. Treating of a chronic subdural hematoma could be conservative and operative, including twist drill craniostomy, single or multiple burr hole drainage, and craniotomy. In the patients who underwent a decompression of the hematoma a postoperative hyperperfusion syndrome could be observed, according to literature up to 51,4%. This syndrome is associated risk of postoperative delirium and neurological deterioration.The hyperperfusion syndrome is also observed in traumatic brain injury. A rapid decompression of a subdural hematoma leads to a brain shifting to the skull bones and thus a traumatic brain injury due to decompression. The development of the hyperperfusion syndrome could be related to the decompression of the subdural hematoma in a rapid fashion.

Assessment of Hemodynamic Changes and Hyperperfusion Risk After Extracranial-to-Intracranial Bypass Surgery Using Intraoperative Indocyanine Green–Based Flow Analysis

Intraoperative blood flow assessments during cerebral bypass would ideally assess vessel patency, downstream perfusion, and risk of postoperative hyperperfusion syndrome (HPS). Previous studies using indocyanine green-based flow analyses (ICG-BFA) have identified multiple parameters that can intraoperatively track bypass-related changes in cerebral perfusion and potentially predict postoperative risk of HPS. Herein, we determine the most robust parameter and anatomic location for intraoperative ICG-BFA assessment of bypass-related perfusion changes and prediction of postoperative risk of HPS. Retrospective analysis of an institutional review board-approved prospective database identified patients undergoing superficial temporal artery-to-middle cerebral artery bypass. Demographic and clinical information, as well as manually calculated and automated pre- and postbypass intraoperative ICG-BFA data from cortical, arterial, and venous regions of interest were recorded and analyzed. Seven patients underwent superficial temporal artery-to-middle cerebral artery bypass (4 Moyamoya, 3carotid occlusions). Average age was 48.2 ± 13.9 years (3female, 4 male). Although all parameters measured showed trends toward improvement postbypass, only changes in arterial and venous automated ICG-BFA slope (also known as blood flow index [maximum intensity/rise time]) reached significance. None of the patients experienced symptomatic HPS, despite 5 of 7 (71.4%) having an increased HPS risk based on previously published ICG-BFA data. ICG-BFA has utility for the intraoperative assessment of bypass-related changes in cerebral perfusion, with automated blood flow index being the most robustly affected parameter. Although previously published ICG-BFA indices did not predict the development of symptomatic postoperative HPS, larger-scale studies correlating observed ICG-BFA changes with risk of HPS are warranted.

Abstract WP355: Evaluation of a Checklist to Identify Early Signs of Hyperperfusion Syndrome After Carotid Endarterectomy

Background and purpose: Hyperperfusion syndrome (HPS) occurs in only 1-3% of patients after carotid endarterectomy (CEA). However, it can cause severe cerebral hemorrhage and may be lethal. Therefore, nurses need to be able to recognize the early signs of HPS and report them to the physician. In this study, we aimed to investigate the applicability of using the Intensive Care Delirium Screening Checklist (ICDSC) to discover early signs of postoperative HPS after CEA, allowing nurses to report the signs and possibly prevent disease progression. Method: The study included 96 Japanese patients average age 71.9 ± 8.3 years old undergoing CEA from May 2008 to May 2017. There were 9 patients in the HPS group and 87 in the non-HPS group. Research design was a methodological study. To analyze differences between normally distributed continuous variables, the average value ± standard deviation was calculated and a t test used to compare between groups. For non-normally distributed continuous variables, the median and the range were calculated, and the Wilcoxon rank sum test was used to compare between groups. Ethical approval was granted by the Ethics Review Committee of the research execution facility. Result: There was no significant difference in the patient characteristics in both groups. There was also no significant difference in the number of patients exhibiting signs of delirium (&gt;4 points in total on the ICDSC) between the HPS group (n=8) and the non-HPS group (n=10). However, patients in the HPS group were unable to engage in conversation, while those in the non-HPS group responded to the nurses’ questions and several patients were able to engage in lucid conversation. The HPS group thus scored significantly higher than the non-HPS group on the "inappropriate speech or mood" ICDSC item (100% in the HPS group vs. 20% in the non-HPS group, P &lt;0.001). In addition, on the "symptom fluctuation" item, the non-HPS group scored significantly higher than the HPS group (0% in the HPS group vs. 100% in the non-HPS group, P &lt;0.001). Conclusion: A total ICDSC score &gt;4 and the presence of "inappropriate speech or mood" or "symptom fluctuation" strongly suggest the presence of HPS. In conclusion suggest that ICDSC is effective in identifying the early clinical signs of HPS after CEA.

Correlation between reduction in microvascular transit time after superficial temporal artery-middle cerebral artery bypass surgery for moyamoya disease and the development of postoperative hyperperfusion syndrome.

OBJECTIVE Hyperperfusion syndrome (HPS) is a notable complication that causes various neurological symptoms after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery for moyamoya disease (MMD). The authors used intraoperative indocyanine green (ICG) videoangiography to measure the change in microvascular transit time (MVTT) after bypass surgery. An analysis was then conducted to identify the correlation between change in MVTT and presence of postoperative HPS. METHODS This study included 105 hemispheres of 81 patients with MMD who underwent STA-MCA single bypass surgery between January 2010 and January 2015. Intraoperative ICG videoangiography was performed before and after bypass surgery. The MVTT was calculated from the ICG time intensity curve recorded in the pial arterioles and venules. Multivariate logistic regression analysis was conducted to test the effect of multiple variables, including the change in MVTT after bypass surgery, on postoperative HPS. RESULTS Postoperative HPS developed in 28 (26.7%) of the 105 hemispheres operated on. MVTT was reduced significantly after bypass surgery (prebypass 5.34 ± 2.00 sec vs postbypass 4.12 ± 1.60 sec; p < 0.001). The difference between prebypass and postbypass MVTT values, defined as ΔMVTT, was significantly greater in the HPS group than in the non-HPS group (2.55 ± 2.66 sec vs 0.75 ± 1.78 sec; p < 0.001). Receiver operating characteristic curve analysis revealed that the optimal cutoff point of ΔMVTT was 2.6 seconds (sensitivity 46.4% and specificity 85.7% as a predictor of postoperative HPS). A ΔMVTT > 2.6 seconds was an independent predictor of HPS in multivariate analysis (hazard ratio 4.88, 95% CI 1.76-13.57; p = 0.002). CONCLUSIONS MVTT in patients with MMD was reduced significantly after bypass surgery. Patients with a ΔMVTT > 2.6 seconds tended to develop postoperative HPS. Because ΔMVTT can be easily measured during surgery, it is a useful diagnostic tool for identifying patients at high risk for HPS after STA-MCA bypass surgery for MMD.

偽閉塞症例に対する頚動脈ステント留置術─周術期管理と手技上の工夫─

The operative indication for pseudo-occlusion of the internal carotid artery is controversial. In this study, we report the technical aspects of and periprocedural care in carotid artery stenting (CAS) for the treatment of this condition. Nineteen cases of pseudo-occlusion of the internal carotid artery (17 symptomatic, 2 asymptomatic) were treated with stenting. Acetazolamide-enhanced singlephoton emission computed tomography revealed hemodynamic compromise in 14 of the 19 cases. To prevent postoperative hyperperfusion syndrome, staged angioplasty and stenting were performed in seven cases. All cases were treated with a flow reversal embolic protection technique during the initial treatment. We observed postoperative intracerebral hemorrhage in one patient due to postoperative hyperperfusion syndrome. Thereafter, we used dexmedetomidine (DEX), a selective α-adrenergic agent, as an intra- and postoperative sedative and analgesic agent, in nine cases to stabilize intraoperative hemodynamics. After staged percutaneous transluminal angioplasty and periprocedural use of DEX, we did not observe hyperperfusion syndrome after CAS. In five cases with extremely tight lesions, we experienced difficulties in crossing the guidewire. In such cases, we applied a 0.014-in coronary chronic total occlusion guidewire to cross the lesions. In this study, we demonstrated fairly positive outcomes of CAS in patients with pseudo-occlusion of the internal carotid artery. This was achieved by focusing on the prevention of hyperperfusion syndrome and proper management of perioperative procedures, especially with respect to blood pressure control.

Quantitative cerebral perfusion assessment using microscope-integrated analysis of intraoperative indocyanine green fluorescence angiography versus positron emission tomography in superficial temporal artery to middle cerebral artery anastomosis.

Background:Intraoperative qualitative indocyanine green (ICG) angiography has been used in cerebrovascular surgery. Hyperperfusion may lead to neurological complications after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis. The purpose of this study is to quantitatively evaluate intraoperative cerebral perfusion using microscope-integrated dynamic ICG fluorescence analysis, and to assess whether this value predicts hyperperfusion syndrome (HPS) after STA-MCA anastomosis.Methods:Ten patients undergoing STA-MCA anastomosis due to unilateral major cerebral artery occlusive disease were included. Ten patients with normal cerebral perfusion served as controls. The ICG transit curve from six regions of interest (ROIs) on the cortex, corresponding to ROIs on positron emission tomography (PET) study, was recorded. Maximum intensity (IMAX), cerebral blood flow index (CBFi), rise time (RT), and time to peak (TTP) were evaluated.Results:RT/TTP, but not IMAX or CBFi, could differentiate between control and study subjects. RT/TTP correlated (|r| = 0.534-0.807; P < 0.01) with mean transit time (MTT)/MTT ratio in the ipsilateral to contralateral hemisphere by PET study. Bland–Altman analysis showed a wide limit of agreement between RT and MTT and between TTP and MTT. The ratio of RT before and after bypass procedures was significantly lower in patients with postoperative HPS than in patients without postoperative HPS (0.60 ± 0.032 and 0.80 ± 0.056, respectively; P = 0.017). The ratio of TTP was also significantly lower in patients with postoperative HPS than in patients without postoperative HPS (0.64 ± 0.081 and 0.85 ± 0.095, respectively; P = 0.017).Conclusions:Time-dependent intraoperative parameters from the ICG transit curve provide quantitative information regarding cerebral circulation time with quality and utility comparable to information obtained by PET. These parameters may help predict the occurrence of postoperative HPS.

The potential benefits and the role of cerebral monitoring in carotid endarterectomy

The benefit of carotid endarterectomy (CEA) in patients with symptomatic severe carotid stenosis is highly dependent on the perioperative stroke rate. Cerebral monitoring plays an important role in reducing the perioperative stroke rate as it allows detection of the main causes of perioperative stroke, being embolism, intraoperative hypoperfusion and postoperative hyperperfusion syndrome. However, some physicians doubt about the benefit of cerebral monitoring and consider it costly and time consuming. The aim of this review is to provide an overview of the available cerebral monitoring modalities and their role in CEA. Electroencephalography, transcranial Doppler, stump pressure and sensory-evoked potentials, are known and used for years. Near-infrared spectroscopy is a relatively new valuable technique, as it is noninvasive, easy to apply and applicable in all CEA patients, but remains to be validated. In our opinion, cerebral monitoring during CEA is essential because it provides direct information regarding new neurological deficits, which might otherwise be missed. Intraoperative cerebral monitoring provides immediate feedback to the treating physician allowing prompt correction in tissue handling. Several monitoring modalities are available for cerebral monitoring in CEA, but no single test is comprehensive. Therefore, a combination of several monitoring modalities with each specific strength not only during but also after CEA is recommended to cover all needs and reduce the perioperative stroke rate.

Hyperperfusion Syndrome in Small-for-Size Livers

Background: Portal hyperperfusion in small-for-size livers might seriously impair postoperative liver regeneration. Using an experimental model, we investigated splenectomy as a measure to reduce portal blood flow and its impact on postoperative recovery following extended liver resection. Method: Wistar rats underwent partial (90%) hepatectomy with or without splenectomy under temporary inflow occlusion (30 min). In addition to 10-day survival rate, laser Doppler flowmetry of hepatic blood flow and fluorescence microscopic analysis of hepatic microcirculation were performed to assess the effect of splenectomy on initial microvascular reperfusion of liver remnants. Results: While postischemic perfusion failure was comparable between both groups, portal blood flow was significantly reduced after simultaneous splenectomy (3.5 ± 0.4 vs. 5.4 ± 0.4 ml/min). Moreover, red blood cell velocity and volumetric blood flow were reduced in splenectomized animals. These animals experienced lower AST levels (421 ± 36 vs. 574 ± 73 U/l) and a significantly increased survival rate, reaching 6.6 ± 1.3 vs 2.6 ± 0.8 days. Conclusion: Simultaneous splenectomy significantly reduced the risk for postoperative hyperperfusion syndrome in small-for-size livers. Shear-stress-induced liver injury was diminished due to a significant reduction of portal venous blood flow, which positively influenced postoperative regeneration resulting in significantly higher survival.

Ｎｅａｒ ｏｃｃｌｕｓｉｏｎを呈する頚部頚動脈狭窄病変に対するＣＥＡ

Near occlusion of the carotid artery has been defined as very severe stenosis at the site of the residual lumen, delayed flow of angiographic contrast material, and reduced arterial caliber secondary to artery collapse. The management of a patient with an atherosclerotic near occlusion of the carotid artery remains controversial. We basically treat patients with carotid near occlusion with carotid endarterectomy (CEA). In the present study, we investigated the surgical indications for the lesion, benefits of CEA, and intraoperative technique and devices. Seven male patients with near occlusion (55-69 years old) were recently treated with CEA during a 4-year period in our institute. Preoperative angiogram and B-mode Doppler did not demonstrate the distal end of the stenotic lesion clearly. All the patients had symptomatic carotid stenotic lesions. We applied the intravascular ultrasound (IVUS) catheter extravascularly to the cervical carotid arteries to obtain intraoperative ultrasound images during CEA not only to expose the lesions sufficiently but also to place the shunt system safely. Extravascular application of IVUS catheter before making arteriotomies correctly depicted the distal ends of the internal carotid artery (ICA) stenotic lesions as a thin layer of vascular wall. Postoperative angiography or MRA demonstrated sufficient intracranial blood flow in the patients with near occlusion treated with CEA. Although the patients did not have any perioperative surgical complications in the present series, we should always pay attention to prevent postoperative hyperperfusion syndrome in cases of carotid near occlusion. We consider CEA beneficial for near occlusion with a low complication rate, which was not more dangerous than in CEA for usual patients with carotid stenotic lesions.

頚動脈病変の治療：ｓｔｅｎｔとＣＥＡ ＣＥＡの現状 ＩＩ：手術リスク，手技と合併症対策，急性期対応

We report surgical risks and complications in patients undergoing carotid endarterectomy (CEA) for carotid occlusive diseases by analyzing the results of a nationwide questionnaire. In 1014 patients who underwent CEA in Japan for 2 years from 2000 to 2001, the rate of disabling stroke and death was 1.9%, and in 394 patients who underwent endovascular surgery including stent placement for carotid artery stenosis during the same period, the rate of disabling stroke and death was 4.5%.From our experience of 336 patients who underwent CEA in our institute between 1975 and 2002, ischemic heart disease was a major cause of death during the CEA perioperative and follow-up periods. Combined angiography and careful management of coronary artery stenosis can be expected to decrease the mortality and morbidity in patients treated with CEA. Intraoperative multiple monitoring system using deviation ration topography of EEG, somatosensory evoked potentials, near-infrared spectrophotometry for measurement of cerebral regional SO2 and transcranial Doppler ultrasonography (TCD) is useful to prevent ischemic complications. Postoperative hyperperfusion syndrome can be checked serially and non-invasively by using TCD. The management of acute stroke patients with thrombosed occlusion or sever stenosis of the internal carotid artery is still controversial. Acute stage CEA was taken into consideration to treat the patients only in 5 (9%) of the 54 Japanese institutes which answered the questionnaire.

Stroke from carotid endarterectomy: when and how to reduce perioperative stroke rate?

To analyse four years of CEA with respect to the underlying mechanisms of perioperative stroke and the role of intraoperative monitoring in the prevention of stroke. From January 1996 through December 1999, 599 CEAs were performed in 404 men and 195 women (mean age: 65 years, range: 39-88). All operations were performed under general anaesthesia using computerised electroencephalography (EEG) and transcranial Doppler (TCD). Any new or any extension of an existing focal cerebral deficit, as well as stroke-related death were registered. Perioperative strokes were classified by time of onset (intraoperative or postoperative), outcome (minor or major stroke), and side (ipsilateral or contralateral). Stroke aetiology was assessed intraoperatively by means of EEG, TCD, completion arteriography or immediate re-exploration, and postoperatively by duplex sonography, computerised tomography (CT) or magnetic resonance imaging (MRI) of the head. Perioperative stroke or death occurred in 20 (3.3%) patients. In four operations stroke was apparent immediately after surgery. Mechanisms of these strokes were ipsilateral carotid artery occlusion (1) and embolisation (3). In 16 patients stroke developed after a symptom-free interval (2-72 h, mean 18 h) due to occlusion of the internal carotid artery on the side of surgery (9). Other mechanisms were: contralateral occlusion of the internal carotid artery (1), postoperative hyperperfusion syndrome (1), intracerebral haemorrhage (1), and contralateral ischaemia due to prolonged clamping (1). In three procedures the cause was unknown. In our experience most strokes from CEA developed after a symptom-free interval and mainly due to thromboembolism of the operated artery. We suggest the introduction of additional TCD monitoring during the immediate postoperative phase.