Efficacy of intraoperative HyperEye Medical System angiography for coronary artery bypass grafting

Application of indocyanine green in surgery: A review of current evidence and implementation in trauma patients

Background: Modern surgical medicine strives to manage trauma while improving outcomes using functional imaging. Identification of viable tissues is crucial for the surgical management of polytrauma and burn patients presenting with soft tissue and hollow viscus injuries. Bowel anastomosis after trauma-related resection is associated with a high rate of leakage. The ability of the surgeon’s bare eye to determine bowel viability remains limited, and the need for a more standardized objective assessment has not yet been fulfilled. Hence, there is a need for more precise diagnostic tools to enhance surgical evaluation and visualization to aid early diagnosis and timely management to minimize trauma-associated complications. Indocyanine green (ICG) coupled with fluorescence angiography is a potential solution for this problem. ICG is a fluorescent dye that responds to near-infrared irradiation. Methods: We conducted a narrative review to address the utility of ICG in the surgical management of patients with trauma as well as elective surgery. Discussion: ICG has many applications in different medical fields and has recently become an important clinical indicator for surgical guidance. However, there is a paucity of information regarding the use of this technology to treat traumas. Recently, angiography with ICG has been introduced in clinical practice to visualize and quantify organ perfusion under several conditions, leading to fewer cases of anastomotic insufficiency. This has great potential to bridge this gap and enhance the clinical outcomes of surgery and patient safety. However, there is no consensus on the ideal dose, time, and manner of administration nor the indications that ICG provides a genuine advantage through greater safety in trauma surgical settings. Conclusions: There is a scarcity of publications describing the use of ICG in trauma patients as a potentially useful strategy to facilitate intraoperative decisions and to limit the extent of surgical resection. This review will improve our understanding of the utility of intraoperative ICG fluorescence in guiding and assisting trauma surgeons to deal with the intraoperative challenges and thus improve the patients’ operative care and safety in the field of trauma surgery.

Assessing the development status of intraoperative fluorescence imaging for perfusion assessments, using the IDEAL framework

Objectives

Intraoperative fluorescence imaging is currently used in a variety of surgical fields for four main purposes: assessing tissue perfusion; identifying/localizing cancer; mapping lymphatic systems; and visualizing anatomy. To establish evidence-based guidance for research and practice, understanding the state of research on fluorescence imaging in different surgical fields is needed. We evaluated the evidence on fluorescence imaging for perfusion assessments using the Idea, Development, Exploration, Assessment, Long Term Study (IDEAL) framework, which was designed for describing the stages of innovation in surgery and other interventional procedures.

Design

Narrative literature review with analysis of IDEAL stage of each field of study.

Setting

All publications on intraoperative fluorescence imaging for perfusion assessments reported in PubMed through 2019 were identified for six surgical procedures: coronary artery bypass grafting (CABG), upper gastrointestinal (GI) surgery, colorectal surgery, solid organ transplantation, reconstructive surgery, and cerebral aneurysm surgery.

Main outcome measures

The IDEAL stage of research evidence was determined for each specialty field using a previously described approach.

Results

196 articles (15 003 cases) were selected for analysis. Current status of research evidence was determined to be IDEAL Stage 2a for upper GI and transplantation surgery, IDEAL 2b for CABG, colorectal and cerebral aneurysm surgery, and IDEAL Stage 3 for reconstructive surgery. Using the technique resulted in a high (up to 50%) rate of revisions among surgical procedures, but its efficacy improving postoperative outcomes has not yet been demonstrated by randomized controlled trials in any discipline. Only one possible adverse reaction to intravenous indocyanine green was reported.

Conclusions

Using fluorescence imaging intraoperatively to assess perfusion is feasible and appears useful for surgical decision making across a range of disciplines. Identifying the IDEAL stage of current research knowledge aids in planning further studies to establish the potential for patient benefit.

The impact of the quantitative assessment procedure for coronary artery bypass graft evaluations using high-resolution near-infrared fluorescence angiography

PURPOSE

Near-infrared angiography (NIR) is used for on-site graft assessment during coronary artery bypass grafting. This study evaluated the results of a quantitative NIR assessment using a new high-resolution NIR device (h-NIR) for graft assessment.

METHODS

Forty-three patients were enrolled in our study. Internal thoracic artery (ITA) grafts anastomosed to the left anterior descending artery and examined intraoperatively using h-NIR were included. The ITA grafts were divided into 2 groups for a comparative analysis: patent grafts (P group; n = 37) and failed grafts (F group; n = 6). The graft flow was evaluated by a "quantitative NIR assessment", and the fluorescence luminance intensity (FLI) was measured. Direct observation of the graft and anastomosis with h-NIR was also performed.

RESULTS

The FLI was higher in the P group than in the F group. The receiver operating characteristic analysis revealed the following cut-off values for FLIs depending on imaging duration: 21.1% at 1 s, 35.5% at 2 s, 58.4% at 3 s, and 83.3% at 4 s. The sensitivity and specificity for detecting graft failure were 83.3% and 69.8-80.6%, respectively. Furthermore, h-NIR was also able to visualize arterial dissection in ITA grafts.

CONCLUSIONS

A quantitative NIR assessment with an h-NIR device can improve the detectability of anastomotic stenosis, and h-NIR successfully detected arterial dissection of grafts.

A novel fluorescent cardiac imaging system for preclinical intraoperative angiography

BACKGROUND

Intraoperative coronary angiography can tremendously reduce early coronary bypass graft failures. Fluorescent cardiac imaging provides an advanced method for intraoperative observation and real-time quantitation of blood flow with high resolution.

METHODS

We devised a system comprised of an LED light source, special filters, lenses and a detector for preclinical coronary artery angiography. The optical setup was implemented by using two achromatic doublet lenses, two positive meniscus lenses, a band-pass filter, a pinhole and a CCD sensor. The setup was optimized by Zemax software. Optical design was further challenged to obtain more parallel light beams, less diffusion and higher resolutions to levels as small as arterioles. Ex vivo rat hearts were prepared and coronary arteries were retrogradely perfused by indocyanine green (ICG). Video angiography was employed to assess blood flow and plot time-dependent fluorescence intensity curve (TIC). Quantitation of blood flow was performed by calculating either the gradient of TIC or area under curve. The correlation between blood flow and each calculated parameters was assessed and used to evaluate the quality of flow.

RESULTS

High-resolution images of flow in coronary arteries were obtained as precise as 62 µm vessel diameter, by our custom-made ICG angiography system. The gradient of TIC was 3.4-6.3 s^-1, while the area under curve indicated 712-1282 s values which ultimately gained correlation coefficients of 0.9938 and 0.9951 with relative blood flow, respectively.

CONCLUSION

The present ICG angiography system may facilitate evaluation of blood flow in animal studies of myocardial infarction and coronary artery grafts intraoperatively.

Evolution of photodynamic medicine based on fluorescence image-guided diagnosis using indocyanine green and 5-aminolevulinic acid

New diagnostic techniques based on photodynamic medicine, such as near-infrared fluorescence using indocyanine green (NIR-ICG) and 5-aminolevulinic acid-mediated photodynamic diagnosis (ALA-PDD), are aiding navigation tasks across various fields of surgery. Specifically, NIR-ICG is being used for the intraoperative identification of sentinel lymph nodes or blood vessels in organ resection and for blood flow evaluation in surgery. These ICG-fluorescent imaging techniques could provide an additional and potentially valuable way to identify vascular and lymphatic structures in surrounding tissue. 5-Aminolevulinic acid is a precursor of a photosensitizing substance with affinity for tumors; thus, diagnostic laparoscopy using ALA-PDD in combination should improve the accuracy of detecting peritoneal dissemination in patients with advanced gastric cancer. The ability to overlay fluorescent imaging with conventional color images in real time using ALA-PDD and NIR with ICG would be of immense benefit to surgeons, providing good visualization and detection of target lesions not seen with the naked eye. A multi-center clinical study examining the safety and efficacy of ALA-PDD during laparoscopic examination for patients with advanced gastric cancer is currently underway in the form of doctor-initiated trials, and further verification studies will be conducted. Such imaging capability could have broad potential across cancer and vascular surgery.

Clinical study of video-assisted thoracoscopic surgery wedge resection in early-stage lung cancer by tumor mapping with indocyanine green

Aim

This study aimed to assess the clinical effectiveness of video-assisted thoracoscopic surgery (VATS) in early-stage lung cancer by indocyanine green (ICG) for tumor mapping.

Material and methods

Thirty patients with early-stage lung cancer with peripheral nodules smaller than 2 cm scheduled for computed tomography (CT)-guided microcoil placement followed by ICG tumor mapping by VATS wedge resection were enrolled. After microcoil deployment, 100 to 150 ml of diluted ICG was injected percutaneously near the nodule. The nodule initially was localized solely by using a near-infrared ray (NIR) thoracoscope to visualize ICG fluorescence. Thoracoscopic instruments were used to determine the staple line. Wedge resection was performed after confirmation of the location of the microcoil using fluoroscopy and pathology results.

Results

Thirty patients underwent VATS resection. The median tumor size was 1.3 cm by CT. The median depth from the pleural surface was 1.7 cm (range: 0.5–3.8 cm). The median CT-guided intervention time was 25 min, and VATS procedural time was 50 min. ICG fluorescence was clearly identified in 30 of 30 patients (100%). The surgical margins were all negative on final pathology in all included cases. The final diagnoses were 30 primary lung cancers; none needed additional resection.

Conclusions

CT-guided percutaneous ICG injection and intraoperative NIR localization of small nodules are safe and feasible. These offer surgeons the ease of localization through direct indocyanine green fluorescence imaging without the use of fluoroscopy and may be a complementary technique to preoperative microcoil placement for nonvisible, nonpalpable intrapulmonary nodules.

Influence of residual coronary flow on bypass graft flow for graft assessment using near-infrared fluorescence angiography

PURPOSE

Near-infrared fluorescence angiography (NIR) detects the attenuation of fluorescence luminance intensity (FLI) through coronary artery bypass grafts affected by anastomotic stenosis. This study investigates the influence of residual blood flow of the host coronary artery (Ho) on bypass graft (Gr) FLI using a coronary artery bypass (CABG) model.

METHODS

A mock circuit system was created using artificial vessels and artificial blood was supplied to the Gr and the Ho. We used NIR to examine the changes in FLI through the Gr.

RESULTS

The Gr FLI was significantly attenuated according to the degree of Gr stenosis. The Gr FLI did not differ significantly among all degrees of Ho stenosis. High FLI grafts included grafts with degrees of Gr stenosis ≤ 75%, regardless of the severity of Ho stenosis. Moderate and low FLI grafts had 90 or 99% Gr stenosis, regardless of the severity of Ho stenosis. Gr FLI with 99% Gr stenosis was higher in 99% Ho stenosis than in ≤ 90% Ho stenosis.

CONCLUSIONS

A high Gr FLI indicated the absence of ≥ 90% stenosis in the anastomosis and a low Gr FLI indicated severe stenosis in the anastomosis despite Ho stenosis. High Ho stenosis may prevent the attenuation of Gr FLI in severely stenosed grafts.

Recent fluorescence-based optical imaging for video-assisted thoracoscopic surgery segmentectomy

Background

The importance of fluorescence-based optical imaging in various fields of surgery is increasing. This is a prospective cohort study aimed to investigate the feasibility and efficacy of indocyanine-green fluorescence (ICGF)-based navigation for near-infrared (NIR) thoracoscopic segmentectomy.

Methods

ICGF-based video-assisted thoracoscopic surgery (VATS) segmentectomy was performed in 149 patients. Each patient underwent preoperative evaluation by multidetector-row computed tomography (MDCT), which provided three-dimensional simulations of vascular structures, segmental bronchi, and lung tumor. During the procedure, low-dose ICG (0.25 mg/kg) was injected systemically after the target segmental pulmonary arteries and bronchus were divided. Under NIR-thoracoscopic guidance, an ICG fluorescent line was marked by electric scalpel, followed by division of lung parenchyma along the line by electric scalpel or endoscopic staples.

Results

An intersegmental line of ICGF was visible in 98% of patients, even with the use of low-dose ICG. Neither ICG-related adverse events nor procedure-related major complications occurred. The 5-year overall (OS) and recurrence-free survival (RFS) rates were 91.8% and 98%, respectively. Localized recurrence at the resected site did not occur in any patient.

Conclusions

ICGF-based navigation for NIR VATS segmentectomy for patients with lung cancer is feasible and effective.

Evaluation of graft anastomosis using time-intensity curves and quantitative near-infrared fluorescence angiography during peripheral arterial bypass grafting

Near-infrared fluorescence angiography (NIR) visualizes blood perfusion using the fluorescence property of indocyanine green (ICG). This study aimed to retrospectively determine the usefulness of a quantitative analysis using NIR to predict the patency of peripheral arterial bypass grafts by measuring their fluorescence luminance intensities (FLIs).Thirteen grafts in 11 patients who underwent peripheral arterial bypass grafting were divided into a patent graft group (n = 7) and a failed graft group (n = 6). The changes in the FLIs of ICG opacification through the graft and distal host artery were retrospectively analyzed using stored NIR data. The time-intensity curves (TICs) of ICG opacification through the graft (Q_graft) and distal host artery (Q_distal) were measured. Two parameters, Δ(Q_graft - Q_distal) and integral(Q_graft - Q_distal), were also analyzed.Although not significant, decreases in Q_graft were observed in the failed graft groups. The Q_distal of the failed graft group was significantly attenuated as compared with that of the patent graft group. Δ(Q_graft - Q_distal) increased only in the failed graft group, which indicates widening of the gap in FLI. Integral(Q_graft - Q_distal) was higher in the failed graft group, as it reflects the accumulation of ICG opacification.The TICs were influenced by anastomotic stenosis in the distal site of the host arteries. Our results indicate that the comparison of Δ(Q_graft - Q_distal) and integral (Q_graft - Q_distal) quantitatively analyzed using NIR can potentially predict anastomotic stenosis.

A Case of Anastomotic Stenosis of a Peripheral Arterial Bypass Graft Undetected in Indocyanine Green Angiography

We report the case of a 75-year-old man who underwent right femoral-popliteal bypass surgery. Anastomotic stenosis was overlooked in indocyanine green (ICG) angiography due to opacification on the bypass graft. X-ray angiography revealed slit-shaped stenosis in the distal graft anastomosis that required revision. Although blood flow may be maintained despite of anastomotic stenosis, small decreases in blood flow cannot be detected in ICG angiography. We describe and discuss the pitfalls of qualitative graft assessment using ICG angiography, and compare ICG fluorescence luminance intensity between primary and revised grafts.

Clinical application of photodynamic medicine technology using light-emitting fluorescence imaging based on a specialized luminous source

The natural amino acid 5-aminolevulinic acid (ALA) is a protoporphyrin IX (PpIX) precursor and a new-generation photosensitive substance that accumulates specifically in cancer cells. When indocyanine green (ICG) is irradiated with near-infrared (NIR) light, it shifts to a higher energy state and emits infrared light with a longer wavelength than the irradiated NIR light. Photodynamic diagnosis (PDD) using ALA and ICG-based NIR fluorescence imaging has emerged as a new diagnostic technique. Specifically, in laparoscopic examinations for serosa-invading advanced gastric cancer, peritoneal metastases could be detected by ALA-PDD, but not by conventional visible-light imaging. The HyperEye Medical System (HEMS) can visualize ICG fluorescence as color images simultaneously projected with visible light in real time. This ICG fluorescence method is widely applicable, including for intraoperative identification of sentinel lymph nodes, visualization of blood vessels in organ resection, and blood flow evaluation during surgery. Fluorescence navigation by ALA-PDD and NIR using ICG imaging provides good visualization and detection of the target lesions that is not possible with the naked eye. We propose that this technique should be used in fundamental research on the relationship among cellular dynamics, metabolic enzymes, and tumor tissues, and to evaluate clinical efficacy and safety in multicenter cooperative clinical trials.

Fluorescence-Guided Surgery

Surgical resection of cancer remains an important treatment modality. Despite advances in preoperative imaging, surgery itself is primarily guided by the surgeon’s ability to locate pathology with conventional white light imaging. Fluorescence-guided surgery (FGS) can be used to define tumor location and margins during the procedure. Intraoperative visualization of tumors may not only allow more complete resections but also improve safety by avoiding unnecessary damage to normal tissue which can also reduce operative time and decrease the need for second-look surgeries. A number of new FGS imaging probes have recently been developed, complementing a small but useful number of existing probes. In this review, we describe current and new fluorescent probes that may assist FGS.

Severe hemodynamic instability after indocyanine green injection during off-pump coronary artery bypass grafting: A case report

RATIONALE

The increasingly intraoperative use of indocyanine green (ICG) means that it is necessary to be aware of both its advantages and potential adverse effects.

PATIENT CONCERNS

A 76-year-old woman developed symptoms of sudden severe hemodynamic instability while undergoing coronary artery bypass grafting with ICG injection to detect the patency of the graft. The main clinical manifestations were a sudden drop in blood pressure and increased heart rate.

DIAGNOSES

Severe side effects or allergic reaction of ICG.

INTERVENTIONS

Cardiopulmonary bypass (CPB) was established, and an intra-aortic balloon pump was implanted in the left femoral artery after intravenous epinephrine and manual cardiac compression failed.

OUTCOMES

The patient was extubated and transferred to the general ward on the third postoperative day.

LESSONS

Invasive blood pressure monitoring should be carried out in patients undergoing intraoperative ICG administration. Anesthetists should pay close attention to the patient's hemodynamic fluctuations, and effective emergency measures should be implemented immediately if severe hemodynamic instability occurs.

Gastric Tube Reconstruction with Superdrainage Using Indocyanine Green Fluorescence During Esophagectomy

We report a case of gastric tube reconstruction with superdrainage using indocyanine green fluorescence during esophagectomy for esophageal cancer. A 53-year-old man with a history of early esophageal cancer treated with endoscopic mucosal dissection experienced esophageal cancer recurrence. There was no evidence of lymph node involvement or distant metastasis on computed tomography; therefore, we performed thoracoscopic esophagectomy. After thoracoscopic esophagectomy, we created a gastric tube. When pulling up the gastric tube through the post-mediastinum route, a root of the right gastroepiploic vein was injured. We subsequently performed superdrainage to avoid congestion of the gastric tube with omental vein and pre-tracheal vein anastomosis at the neck, and confirmed venous flow using the indocyanine green fluorescence method. No postoperative anastomotic leakage was observed, and the patient was discharged 22 days after surgery. Thus, we recommend the indocyanine green fluorescence method in cases involving superdrainage during esophagectomy.

Influence of vessel stenosis on indocyanine green fluorescence intensity assessed by near-infrared fluorescence angiography

PURPOSE

Although useful for visualizing blood flow during revascularization surgery, the permeability of near-infrared fluorescence (NIR) angiography using indocyanine green (ICG) does not allow for vessel stenosis visualization. We hypothesized that changes in ICG fluorescence intensity reflect vessel stenosis, and evaluated the influence of stenosis on blood flow by ex vivo experimentation.

METHODS

The vessel stenosis model comprised a silicon tube, a graft occluder, and artificial blood. During near-infrared angiography, the fluorescense intensity was calculated during pre- and post-stenosis of an artificial circuit, using a NIR angiography. We measured the maximum fluorescence intensity and the time to maximum fluorescence intensity.

RESULTS

Severe stenosis (≥75%) attenuated the increase in ICG fluorescence intensity in the tube significantly, pre- and post-stenosis. The time to maximum fluorescence intensity did not differ between sites pre- and post-stenosis, irrespective of stenosis severity.

CONCLUSION

Stenosis affected the ICG fluorescence intensity through the vessel. Thus, quantitative analysis using NIR angiography may detect severe vessel stenosis (≥75%), and the extinction curve of indocyanine fluorescence intensity may support the evaluation of blood flow. The absence of differences in the time to maximum fluorescence intensity for degrees of stenosis might suggest a limitation of previous conventional qualitative assessments.

Short- and long-term results of radial artery and saphenous vein grafts in the right coronary system: a propensity-matched study

PURPOSE

The selection of optimal grafts for the right coronary artery remains controversial. This study aims to evaluate the short- and long-term results of radial artery (RA) grafts and saphenous vein grafts (SVGs) to the right coronary artery.

METHODS

We reviewed, retrospectively, isolated coronary artery bypass grafts, placed between 1997 and 2007, and compared the long-term results of patients who received RA (n = 110) grafts with those of patients who received SVGs (n = 264) using propensity-score matching for risk. The preoperative predictors of graft occlusion were investigated on a per case basis.

RESULTS

Superior survival was noted in the unmatched RA group, but late outcomes after propensity-score matching yielded 91 patient pairs that were similar in the two groups. Graft failure was not correlated with mortality, but showed strong correlation with cardiac events in all patients. The predictors of graft occlusion in the RA group were mild proximal stenosis and low indexing glomerular filtration rates for body surface area, whereas those in the SVG were female gender and off-pump coronary artery bypass grafting.

CONCLUSIONS

There were no significant differences in long-term outcomes between the RA and SVG groups. Predictors of graft occlusion differed between the groups. Notably, renal dysfunction impaired radial patency, emphasizing the importance of careful graft selection.

Quantitative assessment technique of HyperEye medical system angiography for coronary artery bypass grafting

PURPOSE

The HyperEye Medical System (HEMS) uses indocyanine green (ICG) to visualize blood vessels in coronary artery bypass grafting (CABG). We performed quantitative HEMS assessment to detect grafts at risk of occlusion.

METHODS

We assessed the HEMS angiograms of 177 grafts from 69 patients who underwent CABG and compared the results with those of fluoroscopic coronary angiography, by measuring the increasing rate of ICG intensity, average acceleration value, and time to peak luminance intensity.

RESULTS

Grafts in the patent and failed groups showed significant differences in their increasing rate of intensity and average acceleration value. The average accelerations value of ICG intensity of internal thoracic artery (ITA) and saphenous vein (SV) grafts were 112.3 and 144.9 intensity/s² in the patent group, and 71.0 and 91.8 intensity/s² in the failed group. The time to peak luminance intensity was 1.7 and 1.4 s in the patent group and 2.3 and 1.9 s in the failed group; these values were not significantly different.

CONCLUSION

Significant reductions in the ICG intensity rate and average acceleration value can occur in failed grafts. Therefore, quantifiable changes in ICG intensity may help detect minute changes in blood flow.

Recent advances in near-infrared fluorescence-guided imaging surgery using indocyanine green

Near-infrared (NIR) fluorescence imaging has better tissue penetration, allowing for the effective rejection of excitation light and detection deep inside organs. Indocyanine green (ICG) generates NIR fluorescence after illumination by an NIR ray, enabling real-time intraoperative visualization of superficial lymphatic channels and vessels transcutaneously. The HyperEye Medical System (HEMS) can simultaneously detect NIR rays under room light to provide color imaging, which enables visualization under bright light. Thus, NIR fluorescence imaging using ICG can provide for excellent diagnostic accuracy in detecting sentinel lymph nodes in cancer and microvascular circulation in various ischemic diseases, to assist us with intraoperative decision making. Including HEMS in this system could further improve the sentinel lymph node mapping and intraoperative identification of blood supply in reconstructive organs and ischemic diseases, making it more attractive than conventional imaging. Moreover, the development of new laparoscopic imaging systems equipped with NIR will allow fluorescence-guided surgery in a minimally invasive setting. Future directions, including the conjugation of NIR fluorophores to target specific cancer markers might be realistic technology with diagnostic and therapeutic benefits.