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

Complementary role of Indocyanine green video angiography, dual-image video angiography and flow-800

BACKGROUND

Visualization of cerebral vessels, their branches and the surrounding structures are essential during cerebrovascular surgery. Indocyanine green dye-based video angiography is a commonly used technique in cerebrovascular surgery. This paper aims to analyze the real-time imaging of ICG-AG, DIVA, and the use of ICG-VA with Flow 800 to compare their usefulness in surgery.

METHODS

Intraoperative real-time identification of vascular and surrounding structures in twenty nine anterior circulation aneurysms and three posterior circulation aneurysm clipping, one STA-MCA bypass, and two carotid endarterectomies were performed in patients using ICG-VA alone, DIVA, ICG-VA with Flow 800 to analyze and compare each of these methods in details.

RESULTS

ICG-VA and DIVA couldn't visualize perforators in twenty-three cases of cerebral aneurysms clipping when used alone. Compared to that by adding Flow 800 perforators were easily visualized. In three cases, occlusion of perforators after clip application was visualized by DIVA and solved by repositioning surgical clips. In one STA-MCA bypass surgery, adequate blood flow to cortical branches of MCA (M4) from STA branches was assessed with ICG-VA, DIVA, and the use of ICG-VA with Flow 800 color mapping. ICG-VA, DIVA, and Flow 800 observed the lack of blood flow and fluttering atherosclerotic plaques in carotid endarterectomy. In one case of basilar tip aneurysm, we used ICG-VA with Flow 800; the intensity diagram drawn after determining regions of interest showed that there was no flow within the aneurysm sac after clipping.

CONCLUSION

In real-time surgery, a multimodal approach using ICG-VA, DIVA, and ICG-VA with Flow 800 colour mapping can serve as useful tools for better visualization of vascular and surrounding structures. The benefits of flow 800 color mapping, such as determining regions of interest, intensity diagrams, and color-coded images, outweigh the advantages over the ICG-VA and DIVA in the visualization of critical vascular anatomy in humans during surgical procedures.

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.

Vasa Vasorum Densities in Human Carotid Atherosclerosis Is Associated with Plaque Development and Vulnerability

Objective

The extensive vasa vasorum network functions as a conduit for the entry of inflammatory cells or factors that promote the progression of angiogenesis and plaque formation. Therefore, we investigated the correlation between the carotid vasa vasorum activities and carotid plaque vulnerability using indocyanine green video angiography (ICG-VA) during carotid endarterectomy (CEA).

Methods

Sixty-nine patients who underwent CEA were enrolled prospectively from September 2015 to December 2017. During CEA, a bolus of ICG was injected intravenously before and after resecting the atheroma. Additionally, we performed immunohistochemistry using CD68 (a surface marker of macrophages), CD117 (a surface marker of mast cells), and CD4 and CD8 (surface markers of T-cells) antibodies to analyze the resected plaque specimens.

Results

The density of active vasa vasorum was observed in all patients using ICG-VA. The vasa vasorum externa (VVE) and interna (VVI) were seen in 11 (16%) and 57 patients (82.6%), respectively. Macroscopically, the VVE-type patterns were strongly associated with preoperative angiographic instability (81.8%, p=0.005) and carotid plaque vulnerability (90.9%, p=0.017). In contrast, the VVI-type patterns were weakly associated with angiographic instability (31.6%) and plaque vulnerability (49.1%). CD68-stained macrophages and CD117-stained mast cells were observed more frequently in unstable plaques than in stable plaques (p<0.0001, p=0.002, respectively).

Conclusion

The early appearance of VVE, along with the presence of many microvessel channels that provided nutrients to the developing and expanding atheroma during ICG-VA, was strongly associated with unstable carotid plaques. The degree of infiltration of macrophages and mast cells is possibly related to the formation of unstable plaques.

Identification of plaque location using intraoperative indocyanine green during carotid endarterectomy for patient with near occlusion

BACKGROUND

Microscope-integrated near-infrared indocyanine green (ICG) videoangiography (VA) is an effective method of intraoperative blood-flow assessment and identification of plaque location during carotid endarterectomy (CEA). However, the validity of ICG-VA during CEA for patient with near occlusion has not been elucidated.

METHODS

Thirty-four CEA procedures were performed between June 2009 and December 2017 for patient with near occlusion, which are more than 95% stenosis. The lesions were classified into three groups according to the diameter of distal ICA compared with ipsilateral external carotid artery (ECA), as normal diameter (>100%), moderate diameter reduction (50-100%), severe diameter reduction (<50%). Five mg of ICG was injected intravenously before arteriotomy, and ICG-VA was taken to identify the distal end of the plaque. Depiction of the distal end and its accuracy were retrospectively reviewed.

RESULTS

There were 18 cases with normal diameter group, 14 cases with moderate diameter reduction group, and 2 cases with severe diameter reduction group. All but one case in the severe diameter reduction group showed apparent distal end signal which were confirmed by arteriotomy afterward.

CONCLUSIONS

The present study clearly denotes that ICG-VA can visualize the carotid plaque distal end during the CEA, even with the patient with near occlusion. However, it should be noted that there may be a difficulty in visualization of the distal plaque end for patient with severely collapsed distal ICA.

Impact of external carotid artery occlusion at declamping of the external and common carotid arteries during carotid endarterectomy on development of new postoperative ischemic cerebral lesions

OBJECTIVE

The external carotid artery (ECA) is inadvertently occluded during carotid endarterectomy (CEA). The importance of ECA occlusion has been emphasized as a loss of extracranial to intracranial collaterals, a source of chronic embolization, or a site for extended thrombosis during wound closure. This study aimed to determine whether ECA occlusion that inadvertently developed during endarterectomy and that was eventually detected using blood flow measurement of the ECA after declamping of all carotid arteries is a risk factor for development of new postoperative ischemic lesions at declamping of the ECA and common carotid artery (CCA) while clamping the internal carotid artery (ICA). This study also aimed to determine whether intraoperative transcranial Doppler (TCD) monitoring predicts the risk for development of such lesions.

METHODS

This was a prospective observational study that included patients undergoing CEA for severe stenosis (≥70%) of the cervical ICA. When blood flow through the ECA measured using an electromagnetic flow meter decreased rapidly on clamping of only the ECA before carotid clamping for endarterectomy and was not changed by clamping of only the ECA after carotid declamping following endarterectomy, the patient was determined to have developed ECA occlusion. These patients underwent additional endarterectomy for the ECA. TCD monitoring in the ipsilateral middle cerebral artery was also performed throughout surgery to identify microembolic signals (MESs). Brain magnetic resonance diffusion-weighted imaging (DWI) was performed before and after surgery.

RESULTS

There were 104 patients enrolled in the study. Eight patients developed ECA occlusion during surgery. The incidence of intraoperative ECA occlusion was significantly higher in patients without MESs at the phase of ECA and CCA declamping (8/12 [67%]) than in those with MESs (0/92 [0%]; P < .0001). Six patients exhibited new postoperative ischemic lesions on DWI. The incidence of intraoperative ECA occlusion (P < .0001) and the absence of MESs at declamping of the ECA and CCA while clamping the ICA (P <. 0001) were significantly higher in patients with development of new postoperative ischemic lesions on DWI than in those without. Sensitivity and specificity for the absence of MESs at declamping of the ECA and CCA while clamping the ICA for predicting development of new postoperative ischemic lesions on DWI were 100% (6/6) and 94% (92/98), respectively.

CONCLUSIONS

ECA occlusion at declamping of the ECA and CCA while clamping the ICA during CEA is a risk factor for development of new postoperative ischemic lesions. Intraoperative TCD monitoring accurately predicts the risk for development of such lesions.

In vivo detection of atherosclerotic plaque using non-contact and label-free near-infrared hyperspectral imaging

BACKGROUND AND AIMS

Detecting detailed atherosclerotic plaques is important to reduce risk factors during surgery. However, there are few methods to evaluate them during surgery. The aim of this study was to establish an in vivo, non-contact, and label-free imaging method for identifying atherosclerotic plaque lesions from outside vessels with a diffuse-reflectance near-infrared (NIR) hyperspectral imaging (HSI) system.

METHODS

NIR spectra between 1000 and 2350 nm were measured using an NIR HSI imaging system outside the exposed abdominal aorta in five Watanabe Heritable Hyperlipidemic (WHHL) rabbits in vivo. Preprocessed data were input to a supervised machine learning algorithm called a support vector machine (SVM) to create pixel-based images that can predict atherosclerotic plaques within a vessel. The images were compared with histological findings.

RESULTS

Absorbance was significantly higher in plaques than in normal arteries at 1000-1380, 1580-1810, and 1880-2320 nm. Overall predictive performance showed a sensitivity of 0.814 ± 0.017, a specificity of 0.836 ± 0.020, and an accuracy of 0.827 ± 0.008. The area under the receiver operating characteristic curve was 0.905 (95% confidence interval = 0.904-0.906).

CONCLUSIONS

The NIR HSI system combined with a machine learning algorithm enabled accurate detection of atherosclerotic plaques within an internal vessel with high spatial resolution from outside the vessel. The findings indicate that the NIR HSI system can provide non-contact, label-free, and precise localization of atherosclerotic plaques during vascular surgery.

SPY technology as an adjunctive measure for lower extremity perfusion

OBJECTIVE

Lack of a reliable outcome measure often leads to excessive or insufficient interventions for critical limb ischemia (CLI). SPY technology (Novadaq Technologies Inc, Bonita Springs, Fla), widely adapted by plastic and general surgeons, uses laser-assisted fluorescence angiography (LAFA) to assess tissue perfusion. We sought to determine the role of SPY as an alternative, perhaps more reliable outcome measure for vascular interventions.

METHODS

All patients undergoing elective or urgent revascularization for claudication and CLI were prospectively recruited from June 2012 to August 2014. LAFA using SPY technology was performed before and after revascularization procedures under a standard Institutional Review Board-approved protocol. Quantitative measures of perfusion at plantar surfaces were analyzed and compared with ankle-brachial index.

RESULTS

A total of 93 patients with claudication or CLI underwent LAFA before and after a revascularization procedure in the study period. The mean preoperative ankle-brachial index increased from 0.60 to 0.84 (P < .001) after a revascularization procedure. Plantar perfusion as measured by LAFA also improved significantly after intervention. Ingress, defined as the rate at which fluorescence intensity increases on the plantar surface during LAFA, increased from 7.1 to 12.4 units/s (P < .001). Peak perfusion, defined as the difference between the baseline and the peak of fluorescence intensity, increased from 97.1 and 143.9 units (P < .001). Egress, defined as the rate at which intensity diminishes after reaching peak perfusion, increased from 1.0 to 1.9 units/s (P = .035). Procedure-related digital embolization was also observed in several patients despite lack of an angiographic finding.

CONCLUSIONS

This is the largest prospective study evaluating SPY technology in peripheral vascular interventions. Our study shows that SPY is a valuable tool in visualizing real-time procedural outcomes and providing additionally useful information on regional tissue perfusion. Further investigation is warranted to standardize outpatient use and to determine threshold values that predict wound healing.

Visualization of declamping procedure during carotid endarterectomy by ICG videoangiography

BACKGROUND

ICG videoangiography (ICG-VAG) is widely used in neurovascular surgery. In carotid artery disease, it has been used to assess the extent of the plaque and to confirm the removal of the plaque and patency of the artery. We introduce a novel usage of the ICG-VAG to confirm the patency of the external carotid artery (ECA) and superior thyroid artery (STA), which should work as a drainage system of possible debris in the lumen.

METHOD

Consecutive 27 patients with severe internal carotid artery stenosis were employed. Carotid endarterectomy (CEA) was done in the usual fashion. After suturing the arteriotomy, ICG was injected intravenously before reperfusion. Before declamping procedure, ICG-VAG mode was started. As the declamping procedure went on, the assistant judged whether the STA and the ECA were patent by watching the ICG flow on the monitor. After confirming the patency of the ECA-CCA system, the ICA was reperfused.

RESULT

The back flow from the STA was not confirmed in two cases. The back flow from the ECA was confirmed in all 27 cases. In four cases, the ICG-VAG showed air bubbles in the lumen; these bubbles were washed away to the ECA or STA.

CONCLUSION

Using ICG-VAG during the reperfusion procedure of CEA, the patency of the ECA and the STA can be confirmed. It may contribute to reduce embolic complication during reperfusion procedure.

Noninvasive thermographic visualization of the extent of carotid plaque distribution during carotid endarterectomy using an uncooled infrared camera

Background:

Intraoperative thermographic confirmation of the extent of carotid plaque distribution using an uncooled infrared camera was assessed during carotid endarterectomy (CEA).

Methods:

This camera was small, light, and provided high temperature resolution (<0.022 degrees), thus allowing detection of the changes in thermal radiation induced by surface temperature differences.

Results:

Vascular flow of the artery appeared as a light color, and absence of flow as a dark color. Vascular re-flow was recognized as a bright color. Therefore, vascular flow could be evaluated using the uncooled infrared camera during CEA. The uncooled infrared camera offers real-time information on vascular patency and extent of plaque. Spatial resolution and image quality are satisfactory, and the procedure can be repeated easily and safely.

Conclusion:

We have shown that the uncooled infrared camera could be a new and feasible technology for intraoperative imaging of the vascular flow, and isconsidered to be clinically useful during CEA.

Identification of plaque location using indocyanine green videoangiography during carotid endarterectomy

BACKGROUND AND AIMS

The aim of the present study was to assess whether surgical microscope-based indocyanine green (ICG) videoangiography (ICG-VA) using FLOW 800 software provides useful evaluation of blood flow during carotid endarterectomy (CEA).

METHODS

Twenty CEA procedures were performed in 19 patients between July 2011 and January 2012. ICG was injected intravenously before and after CEA, and ICG-VA video sequences were analyzed using FLOW 800. Regions of interest were identified in the common carotid artery, plaque, internal carotid artery, and external carotid artery, and changes in intensity values were evaluated.

RESULTS

The distal and proximal ends of the carotid plaque were identified in 87.5 and 75 % of cases, respectively. After CEA, intensity values in the common carotid artery, plaque, internal carotid artery, and external carotid artery had increased by 162 ± 129, 337 ± 212, 139 ± 151, and 177 ± 143, respectively. The intensity values in the region of the plaque showed the greatest improvement.

CONCLUSIONS

ICG-VA can provide information regarding plaque location vessel patency during CEA. FLOW 800 software provides semiquantitative information regarding blood flow, especially in cases of severe stenosis with collapse of the internal carotid artery.

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.

Post-carotid endarterectomy cerebral hyperperfusion syndrome : is it preventable by strict blood pressure control?

Objective

Cerebral hyperperfusion syndrome (CHS) is a serious complication after carotid endarterectomy (CEA). However, the prevalence of CHS has decreased as techniques have improved. This study evaluates the role of strict blood pressure (BP) control for the prevention of CHS.

Methods

All 18 patients who received CEA from February 2009 through November 2012 were retrospectively reviewed. All patients were routinely managed in an intensive care unit by a same protocol. The cerebral perfusion state was evaluated on the basis of the regional cerebral blood flow (rCBF) study by perfusion computed tomography (pCT) and mean velocity by transcranial doppler (TCD). BP was strictly controlled (<140/90 mm Hg) for 7 days. When either post-CEA hyperperfusion (>100% increase in the rCBF by pCT or in the mean velocity by TCD compared with preoperative values) or CHS was detected, BP was maintained below 120/80 mm Hg.

Results

TCD and pCT data on the patients were analyzed. Ipsilateral rCBF was significantly increased after CEA in the pCT (p=0.049). Post-CEA hyperperfusion was observed in 3 patients (18.7%) in the pCT and 2 patients (12.5%) in the TCD study. No patients developed clinical CHS for one month after CEA. Furthermore, no patients developed additional neurological deficits related to postoperative cerebrovascular complications.

Conclusion

Intensive care with strict BP control (<140/90 mm Hg) achieved a low prevalence of post-CEA hyperperfusion and prevented CHS. This study suggests that intensive care with strict BP control can prevent the prevalence of post-CEA CHS.

Quantitative analysis of intraoperative indocyanine green video angiography in aneurysm surgery

Objective

Indocyanine green (ICG) videoangiography (VA) is being used in assessment of blood flow during cerebrovascular surgery. However, data collected during ICG angiography are usually interpreted qualitatively. In this study, quantitative analysis of ICG angiogram was attempted.

Materials and Methods

ICG VA, performed during aneurysm surgery was analyzed retrospectively. The angiogram was captured serially in regular time interval. The stacked images were then fed into an image analysis program, ImageJ. The selected areas of interest were as follows: parent and branch vessels, and dome of aneurysm. Changes of signals of measurement points were plotted. The time to peak, washout time, and the peak intensity between areas were compared.

Results

Among the 16 cases enrolled in this study, five cases were anterior communicating artery aneurysms, and 11 cases were middle cerebral artery bifurcation aneurysms. There was no signal intensity of aneurysm dome in our series. No difference in time to peak or maximum signal intensity was observed between vessels in each case. The average time to peak was 9.0 and washout time was 31.3 seconds. No significant difference in time profile was observed between anterior communicating artery aneurysms and middle cerebral artery bifurcation aneurysms.

Conclusion

Findings of this study demonstrate that quantitative analysis is possible using a personal computer and common video capture and analysis software. It can be a good adjunctive to evaluation of vascular status during aneurysm surgery. It displays time profiles of multiple points of interest over time, and is helpful in objective evaluation of changes of blood flow over time. It might be helpful in various fields of cerebrovascular surgery.