Objective qualitative and quantitative assessment of blood flow with near-infrared angiography in microvascular anastomoses in the rat model

A Challenging Case of Thumb Replantation Aided by Intraoperative Indocyanine Green Fluorescence Angiography

Background

This study presents a case of thumb replantation performed despite several risk factors: age, comorbidities, and trauma mechanism are major adverse prognostic factors directly impacting thumb replantation. Most of the literature backs up this claim that a thumb that works, even partially, is a better outcome for the patient than amputation.

Methods

We performed thumb replantation on a 94-year-old patient with type 2 diabetes mellitus who arrived at the emergency department with a thumb avulsion due to a dog bite. The intraoperative indocyanine green fluorescence angiography method aided us in carrying out the operation.

Results

We successfully used indocyanine green angiography intraoperatively to guide surgical debridement and evaluate the efficacy of anastomosis and reperfusion of the replanted segment during surgery. Two months after the operation, the patient had regained satisfactory hand function.

Conclusions

Although indocyanine green angiography is not a technology created for revascularization procedures, it is instrumental in assessing vascular function and predicting a successful outcome. Given its undeniable potential, more research is needed on the possibility of widespread use in hand surgery and its indications.

Evaluation of tissue blood supply during esophagectomy using fluorescent diagnostics and diffuse scattering spectroscopy in visible region

BACKGROUND

The success of the surgical treatment of a tumor or obstruction of the esophagus with subsequent anastomosis application depends on the level of blood supply to the stitched tissues. Intraoperative assessment of blood flow is widely used in medicine and can be used as a diagnostic method that affects the outcome of surgery and reduces the frequency of postoperative complications for the patient.

METHODS

In this work, the assessment of blood supply during esophageal resection operations was carried out using two techniques sequentially: fluorescent diagnostics with indocyanine green and measurement of hemoglobin oxygen saturation by diffuse scattering spectroscopy in the visible wavelength range. The first method was used to assess the integrity of the vascular network structure in the area of anastomosis and blood flow through the sutured tissues, the second one - for local assessment of hemoglobin oxygen saturation in the investigated area.

RESULTS

Conducted clinical study involved the participation of nine patients with malignant neoplasms (six cases) or esophageal obstruction (three cases). The presence of postoperative complications was compared with the measurement results. Anastomosis failure was observed in only one patient. According to the results of the study, with the use of the investigated method of assessing blood supply, there is a tendency towards a decrease in the frequency of anastomosis leaks (11.1 % compared with 21.4 %).

CONCLUSIONS

Therefore, fluorescent diagnostics with indocyanine green and measurement of hemoglobin oxygen saturation using diffuse scattering spectroscopy were affirmed as methods that allow increasing the safety of surgical procedures by assessing the risk of postoperative complications, including anastomosis failures.

Lower Extremity Reconstruction with Anterolateral Thigh Free-Flap Anastomoses: A Computational Fluid Dynamic Analysis

BACKGROUND

 The anterolateral thigh free flap is an option for repairing soft tissue defects of the distal lower extremity. This flap uses the descending branch of the lateral circumflex femoral (LCF) artery as the flap vessel. The recipient vessel in these flaps is often the anterior tibial (AT), posterior tibial (PT), or peroneal (P) arteries. Computational fluid dynamic (CFD) evaluation of anastomoses between these vessels can optimize outcomes.

METHODS

 Thirty-eight CFD models were created to model end-to-side (ETS) and end-to-end (ETE) anastomoses for lower extremity reconstruction. Seven out of thirty-eight models represented ETS anastomoses between the LCF and AT arteries with varying anastomotic angles. Nine out of thirty-eight models represented 45-degree ETS anastomoses between varying diameters of the LCF and AT, PT, and P arteries. Nine out of thirty-eight models represented stenosis on the flap vessel and recipient vessel, pre- and post-bifurcation. Nine out of thirty-eight models represented ETE anastomoses, rather than ETS, with varying vessel diameters. Four out of thirty-eight models represented ETE anastomoses with varying regions and levels of stenosis.

RESULTS

 Stasis of blood flow in ETS models increased as anastomotic angle increased in a logarithmic relationship (R 2 = 0.918). Flow was optimized overall as flap and recipient vessel diameters approached one another. In ETS models, flap vessel and postbifurcation recipient vessel stenosis were found to substantially increase stasis.

CONCLUSION

 Selection of flap and recipient vessels with similar diameters can optimize outcomes in microvascular anastomoses. In the context of lower extremity reconstruction with the ALT flap, the PT artery can be recommended as a first-line recipient vessel due to its similar vessel caliber to the LCF and relative ease of surgical access compared with the P artery. Avoidance of areas of stenosis is recommended to ensure laminar flow and reduce the operative difficulty associated with performing anastomoses on nonpliable arteries. Striving for increased acuity of anastomotic angles is recommended to optimize the flow in ETS microvascular anastomoses.

Conditioning of microvascular venous flaps in rats

Venous-only perfusion flaps have not been used widely because of the associated high failure rate. Tissue conditioning offers a broad scope of techniques that can be applied pre-, peri-, or postoperatively to promote the adaptation of the affected tissue to any subsequent stress. This study aimed to assess the survival rates associated with a pure venous perfusion flap and investigate whether the timing of the vascular conditioning can affect free flap survival. Forty-four rats were included in the experiment. Group I underwent veno-arterial anastomoses with epigastric graft with pure venous perfusion without tissue conditioning. Groups II and III were pretreated for 7 or 14 days with ischemic conditioning. These groups were compared with a control group (group IV) of conventionally perfused flaps. After the initial surgery, all flaps were assessed clinically, photometrically, and by indocyanine green videoangiography. The flap success rates were 0% in group I, 49.97% ± 24.34% in group II, and 64.95% ± 20.36% in group III. The control group showed an overall survival of 89.3% ± 6.51%. With suitable conditioning, pure venous blood supply can provide adequate perfusion in the rat epigastric flap model. The timing of vascular conditioning appears to be critical for flap survival.

Preoperative Peroneal Artery Perforator Mapping Using Indocyanine Green Angiography: A Prospective Clinical Trial

BACKGROUND

Perforator imaging is a prerequisite in preoperative planning of the peroneal perforator flap and the fibula skin island. Although reports indicate that indocyanine green angiography assessment method might be advantageous over conventional ultrasound-based techniques (i.e., Doppler and color duplex), in practice, clear evidence is lacking. Thus, a comparative assessment of the utility of indocyanine green angiography and ultrasound-based techniques in the identification of suitable lower leg skin perforators was performed.

METHODS

A prospective clinical cohort study with a series of 12 consecutive patients was conducted to assess indocyanine green angiography, Doppler ultrasound, and color duplex ultrasound techniques for preoperative perforator detection in the lower leg before free fibula flap harvest. Anatomical dissection served as a reference. Parameters measured were perforator spatial distance to the reference (precision), operative time expenditure, and ease of device usage for assessment/outcomes.

RESULTS

This study included 12 patients, with a total of 27 perforators. Exhibition of technique sensitivity and positive predictive values were as follows: indocyanine green angiography, 93 percent and 100 percent; Doppler ultrasound, 82 percent and 82 percent; and color duplex ultrasound, 89 percent and 86 percent, respectively. With regard to the indocyanine green angiography technique, the distance to the actual perforator location was significantly shorter, which aided detection and lesser time expenditure during operation.

CONCLUSIONS

The indocyanine green angiography technique proved to have high precision, sensitivity, positive predictive value, and easy-to-use capabilities because of its exceptional spatial and temporal information, compared to the conventional, ultrasound-based techniques. Therefore, indocyanine green angiography is superior for preoperative perforator imaging of the lateral lower leg.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, II.

Intraoperative ICG-based fluorescence-angiography in head and neck reconstruction: Predictive value for impaired perfusion of free flaps

The aim of this study was to prove the hypothesis that intraoperative fluorescence-angiography using indocyanine-green (ICGFA) can be used to predict the occurrence of perfusion-associated complications following microvascular reconstruction. Consecutively perioperative data of patients who received microvascular reconstruction of the head and neck region and underwent ICGFA immediately after anastomosis was established were analyzed. The flow parameters analyzed in the investigation were (1) the baseline (Int_Min) and (2) peak intensity (Int_Max) of fluorescence, (3) the quotient of the two aforementioned parameters (F_max/min) as an expression of the relative total increase, (4) the absolute difference in the two parameters (Diff_Int) in terms of amplitude, (5) the duration of the intensity increase (T_Rise) until the peak, and (6) the percent intensity increase per second (Rise/sec_rel). Within the first 2 weeks postoperatively, every flap complication was documented. Subsequently, statistical analysis of the flap outcome was performed based on the flow parameters obtained intraoperatively. Data of 67 patients (male/female: 41/26) with an average age of 64 years (range 29-84 years) were analyzed. In 10 of these patients, postoperative perfusion-associated complications were observed (arterial/venous/microcirculatory: 4/3/3; p = 0.12). The analysis of the intraoperatively obtained flow parameters showed a significant difference in the ratio of maximum and minimum intensity in arterial pedicle perfusion (F_max/min) of patients with and without complications (with vs. without complications: 2.3 ± 1.0 vs. 5.0 ± 4.9; p < 0.01) and strong correlation of the mentioned parameter with the occurrence of perfusion-associated complications (odds ratio = 0.27; p = 0.01). The ratio of maximum and minimum intensity (F_max/min) is a predictor for postoperative venous stasis, arterial hypoperfusion and impaired microcirculation of a microvascular flap. Anastomoses with F_max/min <2.85 should be revised. However, a high technique sensitivity has to be considered, due to which sufficient hemostasis and reduction of motion artefacts have to be taken into account in order to obtain useable data.

Anastomotic stenosis of a reconstructed dissecting superior mesenteric artery aneurysm undetectable by intraoperative indocyanine green angiography: A case report

Intraoperative evaluation of blood flow using ICG angiography revealed no significant abnormality. However, the anastomotic stenosis was revealed by postoperative CT angiography; more precise intraoperative evaluation methods need to be developed.

Microvascular anastomosis techniques using the medical adhesive VIVO and expandable micro-stents in a rat carotid artery model

BACKGROUND

Sutured anastomosis remains the gold standard in microvascular surgery. The procedure is not free of complications and is a time-consuming operation requiring a high level of experience. The aim of this study was to develop new methods for a stable, faster, and safer anastomosis using a novel biodegradable adhesive, VIVO, and a custom-made microvascular stent.

METHODS

The VIVO medical adhesive was used for a total of 30 anastomoses in rats in the right carotid artery: 15 anastomoses were performed with a temporary intraluminal catheter, VIVO, and reduced sutures (VIVO + TC). A further 15 anastomoses were performed with nitinol stents, VIVO, and reduced sutures (VIVO + SM). Sutured anastomoses served as controls (C) and were performed on the left carotid arteries of the 30 rats. Operation and bleeding times were assessed, and patency was evaluated by Doppler flowmetry and indocyanine green (ICG) angiography. Subsequently, the anastomoses were evaluated histopathological.

RESULTS

The overall patency was recorded as 100% in all groups. No thrombosis or circulatory disturbance was found. Compared to C and VIVO + SM, VIVO + TC proved to be significantly less traumatic, less demanding, and time-saving. The sealing properties of VIVO lead to shorter bleeding times and less oozing. In contrast, VIVO + SM proved to be the most technically demanding and time-consuming procedure.

CONCLUSION

The success of a microvascular sutured anastomosis is determined by a short ischemic interval. Compared to sutured anastomosis, VIVO + TC showed ease of use as well as shorter time taken for anastomosis, less trauma, and lower blood loss. More long-term studies on the functions, biological interactions, and survival rates of glue-based anastomoses need to be initiated.

Effects of endothelial defects and venous interposition grafts on the acute incidence of thrombus formation within microvascular procedures

Endothelial defects (ED) and the usage of interposition vein grafts (IVG) are known risk factors for free flap failure. This experimental study aimed to compare both situations of thrombus formation and fluorescence angiographic behavior. Indocyanine green videoangiography (ICGVA) with the FLOW 800 tool was systematically performed in groups I = ED, II = IVG, and III = ED and IVG (each n = 11). ICGVA was able to detect thrombosis in five animals and safely ruled it out in 26 with two false-positive cases (sensitivity, specificity, and positive and negative predictive values were 100%, 90%, 62%, and 100%, respectively). The difference between visually and ICGVA-assisted ED measurements was significant (p = 0.04). The areas of thrombosis showed no significant difference. Moreover, ICGVA detected a decrease of all parameters at the ED area and/or within the IVG section in all groups. The presence of an endothelial defect had a higher impact on thrombus formation than the IVG usage. ICGVA is qualitatively able to detect endothelial defects and clinically evident thrombosis. However, the quantitative values are not yet attributable to one of the clinical scenarios that may jeopardize free flap transfer.

A comparative analysis using flowmeter, laser-Doppler |spectrophotometry, and indocyanine green-videoangiography for detection of vascular stenosis in free flaps

The effects of gradual vascular occlusion on the blood supply of perfused areas are poorly described. Information relating to the comparison of flap monitoring techniques is lacking. Varying stenotic conditions (0%, 25%, 50%, 75% and 100%) were generated on purpose at the A. and V. femoralis in the rat model. Analyses included flowmeter, simultaneous laser-Doppler flowmetry and tissue spectrophotometry (O2C) and indocyanine green- (ICG-) videoangiography with integrated FLOW 800 tool. A Random Forests prediction model was used to analyse the importance of each method to diagnose the stenotic conditions. The ability to discriminate and to accurately estimate the probability of stenosis was assessed by Receiver Operating Characteristic (ROC) curves and calibration plots. Blood flow changes for all modalities were described in detail. Flowmeter displayed earliest a linear decrease as a result of increasing stenosis. A stenosis of 50% degrees was most difficult to detect correctly. The combination of flowmeter and ICG-videoangiography showed high diagnostic power for each stenotic situation (area under the ROC > 0.79). Flowmeter and ICG-videoangiography showed to be most relevant in detection of varying stenotic conditions and may change the clinical outcome. The O2C showed less effect on varying stenotic situations as the only surface monitoring device.

Quantitative perfusion assessment of intestinal anastomoses in pigs treated with glucagon-like peptide 2

PURPOSE

Despite exhaustive research and improvement of techniques, anastomotic leakage remains a frequent complication in gastrointestinal surgery. As leakage is associated with poor perfusion, reliable objective methods to assess anastomotic perfusion are highly demanded. In addition, such methods enable evaluation of interventions that may improve anastomotic perfusion. Glucagon-like peptide 2 (GLP-2) is an enteroendocrine hormone that regulates mid-gut perfusion. In the present study, we aimed to explore if quantitative perfusion assessment with indocyanine green (q-ICG) could detect an increase in porcine anastomotic perfusion after treatment with GLP-2.

METHODS

Nineteen pigs had two small bowel resections followed by anastomosis. Blinded to all investigators, animals were randomized to receive GLP-2 or placebo. Anastomotic perfusion was assessed at baseline, 30 min after injection of GLP-2/placebo, and after 5 days of treatment. Anastomotic strength and healing were evaluated by bursting pressure and histology.

RESULTS

Q-ICG detected a significantly higher increase in anastomotic perfusion (p < 0.05) in animals treated with GLP-2, compared with placebo. No significant differences in anastomotic strength or healing were found.

CONCLUSIONS

Q-ICG is a promising tool for perfusion assessment in gastrointestinal surgery and opens new opportunities in research of factors that may influence anastomotic healing, but further research is warranted to evaluate the effects of GLP-2 on anastomotic healing.

Pharmacological thrombolysis: the last choice for salvaging free flaps

Microvascular free flap transfer has become a prevailing surgery with a failure rate of <5%. However, pedicle thrombosis occurs more frequently than indicated by the failure rate. This difference is due to the successful salvage of failing flaps. During exploration, thrombi are often encountered at anastomotic sites, whereas these causes could not explain vascular compromise in other patients. Thus, we hypothesized that thrombogenic processes might occur at remote sites, specifically within microvessels of the transferred flap. This study retrospectively evaluated 323 patients who underwent microvascular free flap transfer between March 2012 and October 2016 at Korea University Guro Hospital. All patients requiring emergency exploration within 7 days after surgery were retrospectively reviewed. Of patients, 15 required explorative surgery for suspected circulatory compromise. Eight were diagnosed with thrombosis at the perianastomotic site and salvaged in accordance with our protocol. There was no detectable thrombosis at the anastomotic site in seven patients, including one patient in whom thrombosis resolved with topical papaverine application and heparinization. The remaining six patients were diagnosed with intra-flap microthrombosis without discernable thrombosis at the anastomotic site. All patients were treated following our urokinase administration protocol and salvaged without complications. Possible external causes should first be evaluated when salvaging free flaps; in the absence of such evidence, urokinase administration may be utilized as a last resort. This study is the first report describing the effectiveness of pharmacological thrombolysis in resolving intra-flap microthrombosis. Furthermore, a safe and efficient urokinase administration protocol is suggested for perianastomotic thrombosis and intra-flap microthrombosis.

Detection of thrombosis in microvessels with indocyanine green videoangiography

Atherosclerosis is a systemic condition that is responsible for many diseases, and becomes a problem in cases where plaques form at several sites. The formation of a thrombotic embolus may jeopardise vascular operations, including microvascular anastomoses in replantation procedures or free tissue transfers. A mobile imaging tool for the detection of thrombosis preoperatively or intraoperatively would be valuable. An intimal injury, simulating removal of atherosclerotic plaques, was made microsurgically in 60 rat aortas, and results were analysed macroscopically, histologically, and with intraoperative indocyanine green (ICG) videoangiography immediately postoperatively. The Spearman and Pearson correlation tests were used to compare the three techniques. The sensitivity and specificity of ICG videoangiography was calculated in relation to both macroscopic and histological results. Detection of thrombosis was possible in 25 cases, and in 18 cases no thrombosis was correctly diagnosed by all methods used. In 31 of 60 specimens formation of thrombus was detected histologically, and in 29 of 60 examinations it was detected clinically, which yielded a correlation of 93.5% between the two examinations. Macroscopic analysis correlated better with ICG videoangiography (sensitivity 86.2% and specificity 64.5%) than histological observations (sensitivity 80.6% and specificity 62.1%). There was a significant correlation among all comparisons (each p≤0.001) with correlation indexes of 0.94, 0.52, and 0.44 for macroscopic/histological, clinical/ICG videoangiographic, and ICG videoangiographic/histological results, respectively. Our results show that ICG videoangiography is an important method for the detection of formation of acute thrombi and may be an important tool in vascular procedures.

Multimodal analysis using flowmeter analysis, laser-Doppler spectrophotometry, and indocyanine green videoangiography for the detection of venous compromise in flaps in rats

Venous congestion results in tissue damage and remains the most common failure of free microvascular transfer if it is not recognized early. The purpose of this experimental study was to evaluate venous congestion and describe the findings with two different monitoring tools. A standardized epigastric flap was raised, and total occlusion of the draining vein was temporarily applied for 4, 5, 6, or 7 h. Blood flow measurements, including laser-Doppler flowmetry, and tissue spectrophotometry (O2C) and indocyanine green (ICG) videoangiography using the FLOW^® 800 tool, were performed systematically after each surgical step, an interval of venous occlusion, and 1 week of clinical observation. Both monitoring tools were capable of detecting acute venous occlusion. ICG videoangiography data showed a significant decrease in the first and second maximum, and the area under the curve, during venous occlusion, whereas hemoglobin levels in the O2C analysis remained stable. Changes in fluorescence values in border areas of the flap correlated significantly with the incidence of necrosis. O2C data later showed significant correlation with the area of necrosis, and more individual changes during flap monitoring. ICG videoangiography might therefore be useful in the prediction of flap necrosis in critical areas of perfusion.

Role of Indocyanine Green in Fluorescence Imaging with Near-Infrared Light to Identify Sentinel Lymph Nodes, Lymphatic Vessels and Pathways Prior to Surgery - A Critical Evaluation of Options

Modern surgical strategies aim to reduce trauma by using functional imaging to improve surgical outcomes. This reviews considers and evaluates the importance of the fluorescent dye indocyanine green (ICG) to visualize lymph nodes, lymphatic pathways and vessels and tissue borders in an interdisciplinary setting. The work is based on a selective search of the literature in PubMed, Scopus, and Google Scholar and the authors' own clinical experience. Because of its simple, radiation-free and uncomplicated application, ICG has become an important clinical indicator in recent years. In oncologic surgery ICG is used extensively to identify sentinel lymph nodes with promising results. In some studies, the detection rates with ICG have been better than the rates obtained with established procedures. When ICG is used for visualization and the quantification of tissue perfusion, it can lead to fewer cases of anastomotic insufficiency or transplant necrosis. The use of ICG for the imaging of organ borders, flap plasty borders and postoperative vascularization has also been scientifically evaluated. Combining the easily applied ICG dye with technical options for intraoperative and interventional visualization has the potential to create new functional imaging procedures which, in future, could expand or even replace existing established surgical techniques, particularly the techniques used for sentinel lymph node and anastomosis imaging.

Intraoperative Anatomical and Hemodynamic Analysis of Intracerebral Arteriovenous Malformations by Semi-quantitative Color-coded Indocyanine Green Videoangiography

Objective and Background:

To evaluate possible roles for indocyanine green (ICG)-based FLOW 800 software in surgical treatment of cerebral arteriovenous malformations (AVMs).

Methods:

We perform ICG videoangiography several times for each step of AVM resection to elucidate feeders, drainers, and cerebral perfusion.

Results:

Since 2010, 22 AVM surgeries in our department have been conducted using FLOW 800 intraoperatively. We demonstrated ICG angiograms, color-coded images, and semi-quantitative curves for AVMs. By reviewing all these modalities, we would define vascular structure of the AVM, proceed with resection, and finally recheck for any remnant.

Conclusions:

ICG FLOW 800 software helps the surgeon to recognize feeding and draining vessels of an AVM intraoperatively. Further studies to evaluate semi-quantitative acquired data regarding blood flow and tissue perfusion are warranted.

Indocyanine green videoangiography-assisted prediction of flap necrosis in the rat epigastric flap using the flow® 800 tool

BACKGROUND

The decision to re-operate on a potentially ischemic free flap remains challenging. Indocyanine green videoangiography (ICG) with the FLOW^® 800 tool is a method which allows an immediate qualitative conclusion about the patency of an anastomosis. Is it also able to predict the outcome of potentially compromised vascular free flaps?

MATERIALS AND METHODS

An epigastric flap was raised and repositioned in 79 rats. Intraoperative fluorescence angiography was performed using ICG videoangiography and the FLOW^® 800 tool was applied. Six regions of interest were positioned systematically over the flap, changes of the ICG fluorescence were color coded with respect to time and 474 measurements were performed. The flap was clinically monitored for one week and the resulting necrotic areas were correlated with the ICG/FLOW^® 800 results.

RESULTS

Mean intensity of clinically vital areas was 83.39 ± 50.96 arbitrary units (AU) and 37.33 ± 15.14 AU in necrotic areas. The receiver operating characteristic curve and Youden-Index analysis revealed that the optimal cutoff for the maximal intensity of ICG after FLOW^® 800 analysis was ≤ 61.733 for the prediction of flap necrosis and > 61.733 for the prediction of flap survival (P < 0.0001; 95% CI = 0.85-0.91; Youden-Index: 0.67). The maximal intensity of ICG angiography had a specificity of 96.1% and sensitivity of 71.4%. The positive predictive value was 97.46% and the corresponding negative predictive value was 61.34%.

CONCLUSION

This demonstrates the potential additional value of ICG videoangiography including FLOW^® 800 analyses in the postoperative monitoring of transplanted flaps. © 2016 Wiley Periodicals, Inc. Microsurgery 37:235-242, 2017.

Near-infrared imaging for the assessment of anastomotic patency, thrombosis, and reperfusion in microsurgery: a pilot study in a porcine model

BACKGROUND

Advances in microsurgical techniques have increased the use of free tissue transfer. Methods of intraoperative flap perfusion assessment, however, still rely primarily on subjective evaluation of traditional clinical parameters. Anastomotic thrombosis, if not expeditiously identified and revised, can result in flap loss with significant associated morbidity. This study aims to evaluate the use of near-infrared (NIR) fluorescence imaging in the assessment of microsurgical anastomotic patency, thrombosis, and vascular revision.

MATERIALS AND METHODS

A model of pedicle thrombosis was created using bilateral abdominal flaps isolated on deep superior epigastric vascular pedicles in four Yorkshire pigs. Following flap elevation, microvascular arterial and venous anastomoses were performed unilaterally, preserving an intact contralateral control flap. Thrombosis was induced at the arterial anastomosis site using ferric chloride, and both flaps imaged using NIR fluorescence angiography. The thrombosed vascular segments were subsequently excised and new anastomoses performed to restore flow. Follow-up imaging of both flaps was then obtained to confirm patency using fluorescence imaging technology.

RESULTS

Pedicled abdominal flaps were created and successful anastomotic thrombosis was induced unilaterally in each pig. Fluorescence imaging technology identified large decreases in tissue perfusion of the thrombosed flap within 2 minutes. After successful revision anastomosis, NIR imaging demonstrated dramatic increase in flow to the reconstructed flap, but intensity did not return to pre-thrombosis levels.

CONCLUSIONS

Early identification of anastomotic thrombosis is important in successful free tissue transfer. Real-time, intraoperative evaluation of flap perfusion, anastomotic thrombosis, and successful revision can be performed using NIR fluorescence imaging.