Intraoperative Imaging: Does it Really Improve Perioperative Outcomes of Carotid Endarterectomy?

An international, multispecialty, expert-based Delphi Consensus document on controversial issues in the management of patients with asymptomatic and symptomatic carotid stenosis

OBJECTIVE

Despite the publication of various national/international guidelines, several questions concerning the management of patients with asymptomatic (AsxCS) and symptomatic (SxCS) carotid stenosis remain unanswered. The aim of this international, multi-specialty, expert-based Delphi Consensus document was to address these issues to help clinicians make decisions when guidelines are unclear.

METHODS

Fourteen controversial topics were identified. A three-round Delphi Consensus process was performed including 61 experts. The aim of Round 1 was to investigate the differing views and opinions regarding these unresolved topics. In Round 2, clarifications were asked from each participant. In Round 3, the questionnaire was resent to all participants for their final vote. Consensus was reached when ≥75% of experts agreed on a specific response.

RESULTS

Most experts agreed that: (1) the current periprocedural/in-hospital stroke/death thresholds for performing a carotid intervention should be lowered from 6% to 4% in patients with SxCS and from 3% to 2% in patients with AsxCS; (2) the time threshold for a patient being considered "recently symptomatic" should be reduced from the current definition of "6 months" to 3 months or less; (3) 80% to 99% AsxCS carries a higher risk of stroke compared with 60% to 79% AsxCS; (4) factors beyond the grade of stenosis and symptoms should be added to the indications for revascularization in AsxCS patients (eg, plaque features of vulnerability and silent infarctions on brain computed tomography scans); and (5) shunting should be used selectively, rather than always or never. Consensus could not be reached on the remaining topics due to conflicting, inadequate, or controversial evidence.

CONCLUSIONS

The present international, multi-specialty expert-based Delphi Consensus document attempted to provide responses to several unanswered/unresolved issues. However, consensus could not be achieved on some topics, highlighting areas requiring future research.

Impact of Routine Intracerebral Completion Angiography on Outcomes After TransCarotid Artery Revascularization

OBJECTIVES

Completion intracerebral angiography (CIA) following transcarotid artery revascularization (TCAR) aims to identify distal embolization after stenting and serve as a measure of intraoperative quality control. Nevertheless, there is no general evidence regarding the benefit of performing routine CIA. The aim of this study was to evaluate the potential risk and benefit of routine CIA.

METHODS

We retrospectively reviewed the Vascular Quality Initiative (VQI) database for transcarotid artery revascularization between 2016-2021. Patients were divided into two groups: patients with no CIA performed and those with completion angiography performed. The primary outcome was in-hospital stroke or death. Secondary outcomes included stroke, death, myocardial infarction (MI) and return to the operating room (RTOR). Clinically relevant and statistically significantly variables on univariable analysis were added to a logistic regression model clustered by center identifier.

RESULTS

A total of 18,155 patients who underwent TCAR were identified, 63.7% of them had routine CIA performed. Patients who had routine CIA were more likely to have contralateral carotid occlusion and general anesthesia. After adjusting for potential confounders, we found no difference in the risk of stroke or death (aOR): 1.03, 95%CI (0.8-1.3), P=.820), stroke/TIA (aOR, 1, 95%CI (0.8-1.3), P=.998), stroke (aOR: 1.1, 95%CI (0.8-1.4), P=.452), death (aOR: 0.98, 95%CI (0.6-1.6), P=.953), MI (aOR: 0.78, 95%CI (0.5-1.2), P=.240), or RTOR (aOR: 1.5, 95%CI (0.6-3.8), P=.412) between patients who had CIA compared to those who did not. A sub-analysis of patients who had new occlusion detected on CIA (69 patients, 0.6%; 19 not treated and 50 treated) indicated higher risk of stroke or death in patients with treated new occlusions (OR: 7.1, 95%CI (2.9-17.3), P<.001) and stroke/TIA (aOR, 5.8, 95%CI (2.3-14.7), P<.001) compared to patients who had no CIA. However, no difference in stroke/death (OR: 3.3, 95%CI (0.37-29.5), P=.283) or stroke/TIA (aOR, 3.1, 95%CI (0.3-29.4), P=.327) was found in patients with non-treated new occlusions compared to patients who had no CIA.

CONCLUSIONS

In this retrospective study, routine performance of completion cerebral angiography was not beneficial with no significant differences in in-hospital stroke or death detected. Detection of new lesions on completion cerebral angiography was rare. Moreover, identifying new occlusions following intracranial angiography was associated with higher odds of stroke or death when these new lesions are treated. Further studies are needed to define the etiology of worse outcomes in patients undergoing intervention for lesions discovered on completion cerebral angiogram and delineate optimal timing for further imaging and intervention.

Completion Arteriogram Following Carotid Endarterectomy Yields Lower Perioperative Stroke Rate

Introduction: Completion imaging following carotid endarterectomy (CEA) remains controversial. We present our experience performing routine completion arteriography (CA). Methods: A retrospective review of our prospectively maintained institutional database was performed for patients undergoing isolated CEA. Results: 1439 isolated CEAs with CA were performed on 1297 patients. CEA was for asymptomatic lesions in 70% (1003) of cases. There were no complications related to arteriography. An abnormal arteriogram documented significant abnormalities in the internal carotid artery (ICA) and prompted revision in 1.7% (24/1439) of cases: 20 unsatisfactory distal endpoints of the endarterectomy (12 residual stenoses, 7 intimal flaps, and 1 dissection), 3 kinks or stenoses within the body of the patch, and 1 thrombus. Of the 20 distal endpoint lesions, stent deployment was used in 17 cases and patch revision in 3 cases. The other 4 cases were treated by patch angioplasty (3) or thrombectomy (1). None suffered a perioperative stroke. The overall 30-day stroke, death, and combined stroke/death rate for the 1439 patients in our series was 1.5% (22), .5% (7), and 1.9% (27), respectively. The combined stroke/death rate for asymptomatic lesions was 1.1% (11/1003) and for symptomatic lesions was 2.5% (11/436). Of the 22 strokes in the entire series (all with normal CA), 15 were non-hemorrhagic strokes ipsilateral to the CEA; 14 were confirmed to have widely patent endarterectomy sites by CT-A (13) or re-exploration and repeat arteriography (1). The occluded site was re-explored and underwent thrombectomy, but no technical problems were identified. The remaining strokes were hemorrhagic (4 reperfusion syndrome and 1 surgical site bleeding) or contralateral to the CEA (2). Conclusion: Although not all patients in this series who underwent intraoperative revision due to abnormal CA might have suffered a stroke, performing this simple and safe study may have halved our overall perioperative stroke rate from 3.2% to 1.5%.

Intraoperative completion studies in carotid endarterectomy: systematic review and meta-analysis of techniques and outcomes

BACKGROUND

Declining perioperative stroke and death rates over the past 3 decades have been paralleled by an increasing use of intraoperative completion studies (ICS) following carotid endarterectomy (CEA). Techniques applied include angiography, intraoperative duplex ultrasound (IDUS), flowmetry, and angioscopy. This systematic review and meta-analysis is aiming on providing an overview of techniques and corresponding outcomes.

METHODS

A PubMed based systematic literature review comprising the years 1980 through 2020 was performed using predefined keywords to identify articles on different ICS techniques. Pooled analyses and meta-analyses estimating risk ratios (RR) and 95% confidence intervals (CI) were performed to compare outcomes of different ICS modes to nonapplication of any ICS. I2 values were assessed to quantify study heterogeneities.

RESULTS

Identification of 34 studies including patients undergoing CEA with angiography (n=53,218), IDUS (n=20,030), flowmetry (n=16,812), and angioscopy (n=2,291). Corresponding rates of perioperative stroke were 1.5%, 1.8%, 3.6%, and 1.5%, perioperative stroke or death occurred in 1.7%, 1.9%, 2.2%, and 2.0%. Intraoperative surgical revision rates were 6.2%, 5.9%, and 7.9% after CEA with angiography, IDUS, and angioscopy, respectively. Compared to nonapplication of any ICS, the pooled analysis revealed angiography to be significantly associated with lower rates of stroke (RR 0.47; 95% CI, 0.36-0.62; P<0.0001) and stroke or death (RR 0.76; 95% CI, 0.70-0.83; P<0.0001). IDUS was significantly associated with lower rates of stroke (RR 0.56; 95% CI, 0.43-0.73; P<0.0001) and stroke or death (RR 0.83; 95% CI, 0.74-0.93; P=0.0018), whereas angioscopy showed a significant association with a lower stroke rate (RR 0.48; 95% CI, 0.033-0.68; P=0.0001), but no effect on the combined stroke or death rate. Angioscopy was associated with a higher intraoperative revision rate compared to angiography (RR 1.29; 95% CI, 1.07-1.54; P=0.006). The meta-analyses confirmed lower perioperative stroke or death rates for angiography (RR 0.83; 95% CI, 0.76-0.91) and IDUS (RR 0.86; 95% CI, 0.76-0.98) compared to non-application of any ICS, whereas flowmetry showed no significant association.

CONCLUSIONS

This study represents the first systematic literature review and meta-analysis on usage of ICSs in CEA. Data strongly indicate a significant beneficial effect of angiography, IDUS, and angioscopy on perioperative CEA outcomes. Any carotid surgeon should consider implementation of ICSs in his routine armamentarium.

Applications of intraoperative Duplex ultrasound in vascular surgery: a systematic review

Objective

This review aims to summarise the contemporary uses of intraoperative completion Duplex ultrasound (IODUS) for the assessment of lower extremity bypass surgery (LEB) and carotid artery endarterectomy (CEA).

Methods

We performed a systematic literature search using the databases of MEDLINE. Eligible studies evaluated the use of IODUS during LEB or CEA.

Results

We found 22 eligible studies; 16 considered the use of IODUS in CEA and 6 in LEB. There was considerable heterogeneity between studies in terms of intervention, outcome measures and follow-up. In the assessment of CEA, there is conflicting evidence regarding the benefits of completion imaging. However, analysis from the largest study suggests a modest reduction in adjusted risk of stroke/mortality when using IODUS selectively (RR 0.74, CI 0.63–0.88, p = 0.001). Evidence also suggests that uncorrected residual flow abnormalities detected on IODUS are associated with higher rates of restenosis (range 2.1% to 20%). In the assessment of LEB, we found a paucity of evidence when considering the benefit of IODUS on patency rates or when considering its utility as compared to other imaging modalities. However, the available evidence suggests higher rates of thrombosis or secondary intervention in grafts with uncorrected residual flow abnormalities (up to 36% at 3 months).

Conclusions

IODUS can be used to detect defects in both CEA and LEB procedures. However, there is a need for more robust prospective studies to determine the best scanning strategy, criteria for intervention and the impact on clinical outcomes.

European Society for Vascular Surgery (ESVS) Certification of Theoretical and Practical Competences in Basic Vascular Ultrasound: Validity Investigation of the Assessment Tools

OBJECTIVE

The aim of this study was to gather validity evidence for the Assessment of basic Vascular Ultrasound Expertise (AVAUSE) tool, and to establish a pass/fail score for each component, to support decisions for certification.

METHODS

A cross sectional validation study performed during the European Society for Vascular Surgery's annual meeting. Validity evidence was sought for the theoretical test and two practical tests based on Messick's framework. The participants were vascular surgeons, vascular surgical trainees, sonographers, and nurses with varying experience levels. Five vascular ultrasound experts developed the theoretical and two practical test components of the AVAUSE tool for each test component. Two stations were set up for carotid examinations and two for superficial venous incompetence (SVI) examinations. Eight raters were assigned in pairs to each station. Three methods were used to set pass/fail scores: contrasting groups' method; rater consensus; and extended Angoff.

RESULTS

Nineteen participants were enrolled. Acceptable internal consistency reliability (Cronbach's alpha) for the AVAUSE theoretical (0.93), carotid (0.84), and SVI (0.65) practical test were shown. In the carotid examination, inter-rater reliability (IRR) for the two rater pairs was good: 0.68 and 0.78, respectively. The carotid scores correlated significantly with years of experience (Pearson's r = 0.56, p = .013) but not with number of examinations in the last five years. For SVI, IRR was excellent at 0.81 and 0.87. SVI performance scores did not correlate with years of experience and number of examinations. The pass/fail score set by the contrasting groups' method was 29 points out of 50. The rater set pass/fail scores were 3.0 points for both carotid and SVI examinations and were used to determine successful participants. Ten of 19 participants passed the tests and were certified.

CONCLUSION

Validity evidence was sought and established for the AVAUSE comprehensive tool, including pass/fail standards. AVAUSE can be used to assess competences in basic vascular ultrasound, allowing operators to progress towards independent practice.

Practice patterns in the use of completion imaging after carotid endarterectomy

BACKGROUND

The use of intraoperative completion imaging (completion carotid duplex ultrasound or angiography) to confirm the technical adequacy of carotid endarterectomy (CEA) remains a matter of controversy. The purpose of this study was to describe vascular surgeons' practice patterns in the use of completion imaging after CEA and to study the association between completion imaging and postoperative stroke/death and high-grade restenosis (>70%).

METHODS

Patients who underwent CEA without concomitant procedures in the Vascular Quality Initiative database between 2003 and 2018 were included. Surgeons' practice patterns were defined on the basis of the distribution of completion imaging use among annual CEA cases per surgeon. Multivariable and Cox proportional hazards models were used to study the association between different practice patterns of completion imaging and perioperative and 1-year outcomes after CEA.

RESULTS

Of 98,055 CEA cases, 26,716 (27.3%) were performed with completion imaging. Compared with cases in which completion imaging was not performed, completion imaging was associated with increased rates of immediate re-exploration (3.5% vs 0.9%; odds ratio [OR], 3.84; 95% confidence interval [CI], 2.74-5.38; P < .001), overall return to the operating room (RTOR; 1.6% vs 1.2%; OR, 1.24; 95% CI, 1.08-1.42; P < .01), and longer operative time (median [interquartile range], 105 minutes [82-132] vs 119 minutes [92-148]; P < .001). Of 1920 surgeons in our cohort, 45% never performed completion imaging, whereas 26% rarely performed completion imaging (for ≤20% of annual CEA cases), 9.5% performed it selectively (21%-79% of annual CEAs), and 19.6% used completion imaging routinely (≥80% of annual CEAs). Rarely performing completion imaging had higher rates of immediate re-exploration (6.5% vs 0.9%; OR, 7.2; 95% CI, 5.7-9.2; P < .001), in-hospital stroke (4.0% vs 1.1%; adjusted OR [aOR], 3.4; 95% CI, 2.6-4.6; P < .001), RTOR for bleeding (1.9% vs 0.9%; aOR, 2.1; 95% CI, 1.5-2.9; P < .001), and neurologic events (1.5% vs 0.4%; aOR, 3.6; 95% CI, 2.2-5.9; P < .001) compared with not performing completion imaging. It was also associated with increased stroke/death and repeated revascularization at 30 days and significant restenosis at 1 year. On the other hand, performance of selective and routine completion imaging was associated with increased immediate re-exploration (selective: aOR, 3.2 [95% CI, 1.9-5.5; P < .001]; routine: aOR, 3.7 [95% CI, 2.5-5.6; P < .001]) without any increase in in-hospital, 30-day, and 1-year adverse outcomes compared with cases performed without completion imaging.

CONCLUSIONS

The performance of selective or routine completion imaging during CEA is safe and is not associated with increased adverse events compared with not using intraoperative completion imaging. However, rarely performing completion imaging is associated with a significant increase in the odds of perioperative stroke/death and RTOR, possibly because of unnecessary re-exploration for minor defects. The operator's experience and establishing a criterion for fixing residual defects are important to avoid unnecessary re-exploration.

Completion imaging techniques and their clinical role after carotid endarterectomy: Systematic review of the literature

BACKGROUND

Completion imaging has been suggested for the intraoperative quality control assessment of the carotid endarterectomy technical success, in order to immediately resolve pathologic findings and accordingly improve patients' outcome. The aim of this study was to present existing evidence of different completion imaging techniques after carotid endarterectomy and their role on clinical outcome.

MATERIAL AND METHODS

A systematic review was performed searching in MEDLINE, CENTRAL, and Cochrane databases including studies reporting on completion imaging techniques after carotid endarterectomy.

RESULTS

A total of 12,378 patients in 35 studies (20 retrospective and 15 prospective) underwent a completion imaging technique after carotid endarterectomy: in 19 studies, 5340 patients underwent arteriography; in 5 studies, 2095 angioscopy; in 21 studies, 5722 DUS; and in 2 studies, 150 patients underwent transcranial Doppler. Ten studies assessed > 1 imaging technique. The mean age was 67 ± 7 years old (69% males) with common co-morbidities to be hypertension (74%), smoking (64%), and hyperlipidemia (54%). Almost half of the patients (4949; 44%) were treated for symptomatic disease. In 1104 (9.7%) patients, a major defect was identified intra-operatively, while in 329 patients (2.9%), a minor defect. Common pathological findings were the presence of mural thrombus, carotid dissection, residual stenosis, and intimal flaps. An immediate re-intervention was undertaken in 75% (790/1053) of the patients to treat a major intra-operative imaging finding. In patients with re-intervention, only 2.3% (14/609) had an intra-operative stroke and 0.8% (5/609), a transient ischemic attack, while only 1.4% (8/575) had a stroke and 0.2% a transient ischemic attack (1/575) during 30-day post-operative period. No intra-operative death was reported. In the same period, the restenosis rate of internal and common carotid artery was 0.5% (3/575) and 0.2% (1/575), respectively.

CONCLUSION

Completion imaging techniques can detect defects in almost 10% of patients that may lead to immediate intra-operative surgical revision with low intra-operative stroke/transient ischemic attack rate and low early carotid restenosis. During the 30-day follow-up period, in those patients, the incidence of stroke/transient ischemic attack may be low but present. This review cannot provide any evidence on which completion imaging technique is better, and the clinical impact conferred by each technique in the absence of a randomized control studies.

Prospective Comparison of Duplex Ultrasound and Angiography for Intra-operative Completion Studies after Carotid Endarterectomy

OBJECTIVE

The application of intra-operative completion studies may have contributed to the ongoing improvement of peri-operative outcomes in carotid surgery.

METHODS

This prospective study aimed to compare angiography and duplex ultrasound (IDUS) as intra-operative completion studies after carotid endarterectomy (CEA) with respect to differences in the rating of vessel wall defects and interobserver reliability. Patients undergoing CEA for symptomatic or asymptomatic carotid stenosis were included. After CEA, angiography and IDUS were performed. Intra-operatively obtained video footage was evaluated at a later date by three independent and blinded raters with different levels of clinical experience. Rating was done according to a four step rating scale, with higher grades representing more severe defects. Standard statistical methods (Pearson's chi square test; permutation test; Wilcoxon signed rank test; Kendall's coefficient of concordance, Wt) were applied.

RESULTS

In total, 150 patients (mean ± standard deviation age 72 ± 7 years, 68.7% male, 33.3% symptomatic) were enrolled between March 2016 and September 2017. Significantly more defects requiring intra-operative revision (grades 3 and 4 on rating scale) were detected by IDUS, which, in part, remained undetected by angiography: 22 (14.7%) vs. 10 (6.7%) (p = .040). Defects were also judged to be more severe with IDUS than with angiography: median rating grade 1: 74 (49.3%) vs. 102 (68.0%); grade 2: 54 (36.0%) vs. 38 (25.3%); grade 3: 21 (14.0%) vs. 9 (6.0%); grade 4: 1 (0.7%) vs.1 (0.7%) (p < .001). Furthermore, Wt was significantly higher for IDUS compared with angiography (0.70 vs. 0.57; p = .003).

CONCLUSION

IDUS revealed more defects after CEA than angiography. Despite both techniques only showing moderate interobserver reliability, IDUS is less dependent on the surgeon's subjectivity than angiography. Taking into account the absence of procedure associated risks (i.e., adverse effects of iodinated contrast media and Xray), IDUS could be considered as an alternative intra-operative morphological assessment tool in carotid surgery.

[Intraoperative completion diagnostics in open vascular surgery]

Intraoperative imaging diagnostics during open vascular surgical procedures aim to enhance diagnostic certainty during the operation, ensure quality control documentation and reduce avoidable complications; however, the evidence for the various diagnostic imaging procedures with respect to improvement of perioperative outcome is not confirmed for carotid endarterectomy or for infrainguinal bypass surgery. Nevertheless, an intraoperative diagnostic control is principally recommended. The advantage of intraoperative imaging is confirmed and essential for the surgical reconstruction of bypass occlusions and acute thromboembolic occlusions.

Intraoperative Computed Tomography Angiography: A Novel Completion Imaging Modality for Carotid Endarterectomy

BACKGROUND

Intraoperative computed tomography angiography (ICTA) is a novel completion imaging modality for carotid endarterectomy (CEA). No studies exist in the literature describing ICTA use in CEA.

OBJECTIVE

To evaluate the feasibility and efficacy of ICTA as a method of immediately evaluating the technical results of CEA.

METHODS

Twenty-three consecutive CEAs were performed by a single neurosurgeon over an 8-month period. Of this series, 12 utilized ICTA for completion imaging, 10 utilized duplex ultrasonography (US), and 1 utilized no intraoperative completion imaging. Electronic medical records were reviewed to assess demographics, CTA results, US results, and need for revisions.

RESULTS

Patients included 13 men (62%) and 8 women (38%). All patients had symptomatic internal carotid artery stenosis. Polytetrafluoroethylene (PTFE) patch angioplasty was used in 16 cases (70%). Average operative times were comparable between cases that utilized CTA and US, 180 and 175 min, respectively. Major technical defects were identified in one of the 12 cases utilizing ICTA and none of the 10 cases utilizing intraoperative US. The technical defect was revised without subsequent neurological complication. One patient had a postoperative intracerebral hemorrhage requiring surgical evacuation. Fifteen patients were followed for up to 3 months with no postoperative stroke or transient ischemic attacks.

CONCLUSION

ICTA is a potentially safe and effective completion imaging modality compared to traditional alternatives, enabling the identification of technical deficits intraoperatively. While no statistically significant difference in operative times were noted between intraoperative CTA and US use, numerous steps must be taken to maximize the efficiency of ICTA.

Intraoperative Completion Studies, Local Anesthesia, and Antiplatelet Medication Are Associated With Lower Risk in Carotid Endarterectomy

Background and Purpose—

In Germany, all surgical and endovascular procedures on the carotid bifurcation must be documented in a statutory nationwide quality assurance database. We aimed to analyze the association between procedural and perioperative variables and in-hospital stroke or death rates after carotid endarterectomy.

Methods—

Between 2009 and 2014, overall 142 074 elective carotid endarterectomy procedures for asymptomatic or symptomatic carotid artery stenosis were documented in the database. The primary outcome of this secondary data analysis was in-hospital stroke or death. Major stroke or death, stroke, and death, each until discharge were secondary outcomes. Adjusted relative risks (RRs) were assessed by multivariable multilevel regression analyses.

Results—

The primary outcome occurred in 1.8% of patients, with a rate of 1.4% in asymptomatic and 2.5% in symptomatic patients, respectively. In the multivariable analysis, lower risks of stroke or death were independently associated with local anesthesia (versus general anesthesia: RR, 0.85; 95% confidence interval [CI], 0.75–0.95), carotid endarterectomy with patch plasty compared with primary closure (RR, 0.71; 95% CI, 0.52–0.97), intraoperative completion studies by duplex ultrasound (RR, 0.74; 95% CI, 0.63–0.88) or angiography (RR, 0.80; 95% CI, 0.71–0.90), and perioperative antiplatelet medication (RR, 0.83; 95% CI, 0.71–0.97). No shunting and a short cross-clamp time were also associated with lower risks; however, these are suspected to be confounded.

Conclusions—

Local anesthesia, patch plasty compared with primary closure, intraoperative completion studies by duplex ultrasound or angiography, and perioperative antiplatelet medication were independently associated with lower in-hospital stroke or death rates after carotid endarterectomy.

Intraoperative sonography during carotid endarterectomy: normal appearance and spectrum of complications

Carotid endarterectomy is a commonly performed procedure for prevention of stroke related to carotid stenosis. Intraoperative sonography is used to identify potentially correctable technical defects during carotid endarterectomy. The main risk of endarterectomy is perioperative stroke, and great effort has been put into trying to reduce this risk through various surgical techniques and evaluation of the surgical bed. Postoperative carotid thrombosis, or thombo-embolization from the arterectomy site, remains a common cause of perioperative stroke and is often related to technical defects in the arterial reconstruction procedure. Re-exploration and repair of any imperfections have the potential to improve outcomes. Intraoperative imaging can identify potentially occult lesions, provide the option for correction, and thus reduce chance of stroke. Familiarity with the spectrum of intraoperative sonographic findings helps correctly identify residual intimal dissection flaps, plaque, thrombi, and stenosis, which may require immediate surgical revision. Our objective is to illustrate the spectrum of intraoperative findings and their importance.

Extravascular optical coherence tomography: evaluation of carotid atherosclerosis and pravastatin therapy

BACKGROUND AND PURPOSE

Extravascular optical coherence tomography (OCT), as a noninvasive imaging methodology with micrometer resolution, was evaluated in a murine model of carotid atherosclerosis by way of assessing the efficacy of pravastatin therapy.

METHODS

An OCT device was engineered for extravascular plaque imaging. Wild-type mice and apolipoprotein E-deficient (ApoE(-/-)) mice were randomized to 3 treatment groups: (1) wild-type on a diet of standard rodent chow (n=13); (2) ApoE(-/-) on a high-fat, atherosclerotic diet (HFD; n=13); and (3) ApoE(-/-) on a HFD given daily pravastatin (n=13). Mice were anesthetized and the left common carotid was surgically exposed. Three-dimensional (3D; 2 spatial dimensions+time) and 4D (3 spatial dimensions+time) OCT images of the vessel lumen patency were evaluated. After perfusion, in situ OCT imaging was performed for statistical comparison with the in vivo results and final histology.

RESULTS

Intraoperative OCT imaging positively identified carotid plaque in 100% of ApoE(-/-) mice on HFD. ApoE(-/-) mice on HFD had a significantly decreased lumen patency when compared with that in wild-type mice (P<0.001). Pravastatin therapy was found to increase lumen patency significantly in ApoE(-/-) mice on HFD (P<0.01; compared with ApoE(-/-) on HFD). The findings were confirmed with OCT imaging after perfusion and histology.

CONCLUSIONS

OCT imaging offers the potential for real-time, detailed vessel lumen evaluation, potentially improving surgical accuracy and outcomes during cerebrovascular neurosurgical procedures. Pravastatin significantly increases vessel lumen patency in the ApoE(-/-) mouse on HFD.

An innovative method for detecting surgical errors using indocyanine green angiography during carotid endarterectomy: a preliminary investigation

BACKGROUND

Carotid endarterectomy (CEA) is the most effective treatment method of carotid stenosis or occlusion. Surgeons typically check the blood flow in each vessel using Duplex Doppler ultrasonography or radiocontrast angiography in order to prevent postoperative complications. Embolic cerebral infarction on the ipsilateral side has been reported in 4-7% of patients undergoing CEA despite a tolerable blood flow reported by Duplex ultrasonography. This study was designed to evaluate a new intraoperative method for detecting technical errors during CEA using indocyanine green (ICG) angiography.

METHODS

Six consecutive patients with severe carotid stenosis or occlusion underwent CEA. Both ICG angiography and Doppler ultrasonography were performed before the carotid arterial incision and after the carotid arterial suture. After injecting ICG dye via an intravenous route, the internal surface, atheroma, and flow defect were visualized with a microscope.

RESULTS

In ICG angiography, stenotic lesions could be identified as regions of relatively dark signal intensity. Magnified real-time images could be created using a microscope with an infrared filter, including three-dimensional images and detailed images of the inner lumen. These images could then be compared with the results of Doppler ultrasonography. In the six cases assessed by both ICG angiography and Doppler ultrasonography, all Doppler results were acceptable. However, one patient underwent revision surgery because a fluttering atheroma was detected by ICG angiography. ICG angiography could assume the extent of severe stenotic area. ICG angiography could also detect mobile lesions such as a fluttering atheroma.

CONCLUSIONS

Intraoperative ICG angiography before arteriotomy is useful to determine the precise stenotic area and the shape of the associated plaque. ICG angiography after an arteriotomy site is sutured is also useful for detecting residual stenosis or fluttering atheroma. ICG angiography could be an alternative method to Doppler ultrasonography for ensuring a complete and successful operation and preventing complications.

Eight-year experience with carotid artery stenting for correction of symptomatic and asymptomatic post-endarterectomy defects

BACKGROUND

Carotid endarterectomy (CEA) has been shown to be superior to medical therapy alone in the prevention of stroke only if it can be safely performed (ie, with a complication rate less than 3% in asymptomatic patients and less than 6% in symptomatic patients). Technical defects are the most common cause of neurological complications after CEA, and their correction has traditionally been performed through standard surgical techniques.

METHODS

From 1999, we started to treat intimal flaps, dissection, or partial thrombosis after CEA with carotid artery stenting (CAS). A retrospective analysis of the operating room registry and of the registry of our Interventional Cardiology laboratory was conducted in order to identify all the patients that underwent stenting of the internal carotid artery after CEA between January 2001 and June 2009.

RESULTS

During the time period considered, 5012 CEA were performed at our institution and a total of 34 patients (34/5012; 0.6%) were found to have received carotid stenting after CEA, both for symptomatic and asymptomatic defects. Immediate technical success was obtained in all patients. One major cerebrovascular adverse event (1/34; 3%) in the immediate perioperative period was recorded. At a mean follow-up of 18.6 months (range, 3-84 months; median, 12 months), we did not observe any neurological symptoms related to the treated carotid artery, nor hemodynamic in-stent restenosis. Long-term follow-up (ie, equal or greater than 4 years) was available for five patients: all patients remained event-free during the entire period.

CONCLUSIONS

Our study adds to the assumption that CAS in post-CEA symptomatic and asymptomatic patients is safe and technically feasible, and represents a valid and quick alternative to standard surgical revision. Even if in a small group of patients, long-term results seem promising.

Completion imaging after carotid endarterectomy in the Vascular Study Group of New England

OBJECTIVES

We studied surgeons' practice patterns in the use of completion imaging (duplex or arteriography), and their association with 30-day stroke/death and 1-year restenosis after carotid endarterectomy (CEA).

METHODS

Using a retrospective analysis of 6115 CEAs, we categorized surgeons based on use of completion imaging as rarely (<5% of CEAs), selective (5% to 90%), or routine (≥90%). Crude and risk-adjusted 30-day stroke/death and 1-year restenosis rates were examined across surgeon practice patterns. Finally, we audited 90 operative reports of patients who underwent re-exploration and characterized findings and interventions. We analyzed the effect of re-exploration on outcomes.

RESULTS

Practice patterns in completion imaging varied: 51% of surgeons performed completion imaging rarely, 22% selectively, and 27% routinely. Crude 30-day stroke/death rates were highest among surgeons who routinely used completion imaging (rarely: 1.7%; selectively: 1.2%, routinely: 2.4%; P = .05). However, after adjusting for patient characteristics predictive of stroke/death, the effect of surgeon practice pattern was not statistically significant (odds ratio [OR] for routine-use surgeons, 1.42; 95% CI, 0.93-2.17; P = .10; selective-use surgeons, 0.75; 95% CI, 0.40-1.41; P = .366). Stenosis >70% at 1 year showed a trend toward lowest rates for surgeons who performed completion imaging (rarely: 2.8%, selectively: 1.1%, and routinely: 1.1%; P = .09). This effect became statistically significant for selective-use surgeons after adjustment (hazard risk [HR] for selective-use surgeons, 0.52; 95% CI, 0.29-0.92; P = .02). Overall, 178 patients (2.9%) underwent operative re-exploration. Routine-use surgeons were most likely to perform re-exploration (7.6% routine, 0.8% selective, 0.9% rare; P < .001). An audit of 90 re-explored patients demonstrated technical problems, the most common being flap, debris, and plaque. Rates of stroke/death were higher among patients who underwent re-exploration (3.9% vs 1.7%; P = .03); however, this affect was attenuated after adjustment (OR, 2.1; 95% CI, 0.9-5.0; P = .08).

CONCLUSIONS

The use of completion imaging during CEA varies widely across our region. There is little evidence that surgeons who use completion imaging have lower rates of 30-day stroke/death, although selective use of completion imaging is associated with a small but a significant reduction in stenosis 1 year after surgery. We also demonstrate an association between re-exploration and higher risk of 30-day stroke/death, although this effect was attenuated after adjustment for patient-level predictors of stroke/death. Future work is needed to direct the selective use of completion imaging to prevent stroke, rather than cause unnecessary re-exploration.