Analysis of Microvascular Free Flap Failure Focusing on the Microscopic Findings of the Anastomosed Vessels

Perioperative anticoagulation in head and neck free flap reconstructions: Experience of an anticoagulative scheme and its modification

OBJECTIVES

Microvascular anastomoses in microvascular reconstructions induce rheological changes in the anastomosed vessels and are usually counteracted by anticoagulative medication. There is no regimen commonly agreed on. This study provides an easy to use anticoagulative regimen.

PATIENTS AND METHODS

Consecutive cases of either anticoagulative regimen between 2013 and 2018 that underwent microvascular reconstruction in the head and neck area were included in this retrospective study, resulting in 400 cases in total. Two different anticoagulative regimens were applied to 200 patients in each group: (a) intraoperatively administered unfractionated 5000 I.U. high molecular weight heparin (HMWH) and postoperatively low molecular weight heparin (LMWH, Enoxaparin) 1 mg/kg/body weight postoperatively and (b) intraoperatively LMWH 0.5 mg/kg/body weight as well as 12 h later and 1 mg/kg/body weight postoperatively.

RESULTS

The LMWH cohort showed fewer overall thromboembolic (8.5% vs. 11%; p = .40) and peripheral thrombotic events (1% vs. 3.5%; p = .18) and lung embolisms (3% vs. 4%; p = .59). The number of thromboses at the site of the anastomosis was equally distributed. In regard to flap-specific complications, LMWH was associated with a positive effect, in particular with respect to total flap losses (5% vs. 7%; p = .40) and wound-healing disorders (14.5% vs. 20%; p = .145).

CONCLUSION

Findings indicate that intra- and postoperatively administered LMWH as the only anticoagulative medication seems reliable in our clinical routine of head and neck free flap reconstructions.

Updates in Traumatic Lower Extremity Free Flap Reconstruction

SUMMARY

Lower extremity reconstruction, particularly in the setting of trauma, remains one of the most challenging tasks for the plastic surgeon. Advances in wound management and microsurgical techniques in conjunction with long-term outcomes studies have expanded possibilities for limb salvage, but many aspects of management have continued to rely on principles set forth by Gustilo and Godina in the 1980s. The purpose of this article is to provide a comprehensive update on the various management aspects of traumatic lower extremity microvascular reconstruction based on the latest evidence, with an examination of recent publications.

Robotic and Microrobotic Tools for Dental Therapy

Robotic and microrobotic tools such as dental operating microscopes and dental endoscopes are being used extensively in dental therapy, which have a significant impact on dental therapy and education. Herein, this paper reviews the state of the art of robotic and microrobotic tools for dental therapy. This article starts with a brief introduction of current robotic and microrobotic tools for dental therapy and then displays their applications in various dental problems; strengths and weaknesses are also surveyed. Lastly, the conclusion and outlook are discussed, referring to the emerging dental clinic problems and demands. This review is expected to provide guidelines for the therapeutic application of robotic and microrobotic tools and to promote the development of robots in dentistry.

Inferior gluteal artery perforator (IGAP) flap versus profunda artery perforator (PAP) flap as an alternative option for free autologous breast reconstruction

BACKGROUND

When patients are unsuitable for deep inferior epigastric perforator (DIEP) flap breast reconstruction, the inferior gluteal artery perforator (IGAP) flap has been used as an alternative option. However, the profunda artery perforator (PAP) flap is also gaining popularity as an alternative to the DIEP flap for several reasons. This retrospective cohort study compares baseline characteristics, peri- and post-operative outcomes following IGAP flap and PAP flap breast reconstructions after mastectomy for cancer.

METHODS

In a single center in the UK, from September 2008 through December 2016, 43 women underwent IGAP Flap(s) breast reconstruction and 51 received PAP flap(s) breast reconstructions. Statistical analysis was performed to compare baseline, peri-operative and post-operative variables between the two reconstruction methods.

RESULTS

Perioperative complications requiring reoperation were experienced in women undergoing IGAP flap breast reconstructions only (21% versus 0%, p = 0.001), principally due to the risk of total flap failure (12% versus 0%, p = 0.01). Women undergoing IGAP flap breast reconstructions were at significantly higher odds of revision surgery (OR 17 [95% CI: 5.5-53], p < 0.001), which was unchanged after adjusting for bilateral reconstructions (adjusted OR 18 [95% CI: 5.3-58], p < 0.001).

CONCLUSIONS

PAP flaps appear to be associated with significantly fewer complications and revision surgeries than IGAP flaps for breast reconstruction in women undergoing mastectomy for cancer and who are unsuitable for a DIEP flap breast reconstruction.

Chronic Expanding Hematoma on Latissimus Dorsi Free Flap Donor Site Grown Over 17 Years

ABSTRACT

The latissimus dorsi free flap (LDFF), that provides long vascular pedicle with rich vascularization and adequate bulk for maxillofacial defect coverage, is utilized in microvascular surgery for maxilla-mandibular reconstruction with high success rate, less morbidity, and ability to provide facial symmetry. In addition, it can reduce the risk of adjuvant therapies, such as radiotherapy. Seroma formation at the donor site following LDFF harvest has been reported as a common postoperative sequela. On the other hand, chronic expanding hematoma (CEH) in an LDFF donor site is a rare postoperative complication. In this case report, the authors describe a rare occurrence of a solidified CEH on an LDFF donor site in a male patient 17 years after mandible reconstruction surgery. For treatment, the patient underwent mass resection with drain placement and quilting suture, resulting in reduction of the hematoma and faster healing.

Pretest and Posttest Evaluation of a Longitudinal, Residency-Integrated Microsurgery Course

INTRODUCTION

Current microsurgical training courses average 5 consecutive 8-hour days and cost US $1500 to US $2500/individual, making training a challenge for residents who are unable to take leave from clinical duties. This residency-integrated microsurgery course was designed for integration with a residency program, averaging 3 hours/week over 7 weeks. This allows for one-on-one training, beginning with synthetic tissue and concluding with in vivo stimulation. This study was performed to validate this longitudinal training course.

METHODS

After recruitment and before the start of coursework, subjects completed a baseline anastomosis without guidance and a survey regarding microsurgical experience. Subjects completed approximately 3 hours/week of practical exercises. Weeks 1 to 5 used synthetic models, whereas 6 to 7 used in vivo rodent models. Nine minimum anastomoses of increasing complexity were completed and assessed with the Anastomosis Lapse Index and the Stanford Microsurgery and Residency Training scale. Scoring was performed by 3 independent reviewers and averaged for comparison.

RESULTS

Five subjects completed the course for study. Presurvey results showed an average confidence in theoretical knowledge of 2/5; technical ability to perform procedures, 1.8/5; and ability to manage complications, 1.8/5. Postsurvey revealed confidence in theoretical knowledge of 2.5/5; technical ability to perform procedures, 2.25/5; and ability to manage complications, 2.25/5. None of these differences were significant. Each individual component of the Stanford Microsurgery and Residency Training scale scoring system improved postcourse with P < 0.05, and overall performance score improved from an average of 2.6 to 3.9 (P = 0.006). The total number of errors recorded using the Anastomosis Lapse Index reduced from 6.58 to 3.41 (P = 0.02). Time to completion reduced from an average of 28 minutes, 8 seconds to 24 minutes, 5 seconds (P = 0.003).

CONCLUSIONS

Despite a lack in significant confidence improvement, completion of the residency-integrated microsurgery course leads to significant and quantifiable improvement in resident microsurgical skill and efficiency.

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.

Endothelial inflammatory and thrombogenic expression changes in microvascular anastomoses - An immunohistochemical analysis

The aim of this study was to investigate intraluminal vessel diameters and endothelial expression levels of pro-inflammatory and -thrombotic mediators in patent and non-patent microvascular anastomoses. Endothelial expression of CD31, VCAM-1, E- and P-Selectin, eNOS, iNOS and PAI-1 was evaluated by immunohistochemistry and compared to non-anastomosed arteries as controls. Intraluminal diameters were determined via H.E.-staining. In 20 human anastomoses (8 patent, 12 non-patent) neither the analysis of endoluminal de-endothelialization (p = 0.966) nor luminal narrowing (p = 0.750) revealed any significant differences between patent and non-patent microanastomoses. Expressions of pro-inflammatory mediators were significantly higher in patent anastomoses compared to controls but did not show any difference compared to non-patent anastomoses (p > 0.050). iNOS was higher in non-patent compared to patent anastomoses (p = 0.030) and controls (p = 0.001), whereas eNOS did not reveal any differences between these groups (p = 0.611 and p = 0.130). In non-patent anastomoses PAI-1 was expressed higher compared to patent anastomoses and controls (p = 0.021 and p < 0.001). Irrespective of their patency, anastomoses are characterized by endothelial dysfunction with a pro-inflammatory and pro-thrombotic milieu. Avoiding endothelial trauma during suturing is essential in order not to aggravate existing endothelial dysfunction in microanastomoses. Additionally, the influence of medication-related changes on anastomoses should be investigated as this is still an indistinctive topic.

Microvascular reconstruction for maxillofacial defects: a retrospective analysis of outcomes and complications in 121 consecutive cases

Background

Microvascular reconstruction is the treatment of choice after oral cancer ablation surgery. There are few published studies of free flap survival among Korean populations. This study aimed to determine the survival rate after 121 consecutive cases of maxillofacial microvascular reconstruction and to analyze the complications associated with microsurgery.

Methods

This study included consecutive patients who underwent microsurgical reconstruction with free flaps, from January 2006 through September 2019, performed by a single surgeon at the oral and maxillofacial surgery department of a tertiary medical center. A total of 121 cases were reviewed retrospectively. The flap survival rate, flap type, radiotherapy history, complications, and treatment results were analyzed.

Results

Four different flap types were used for microvascular reconstruction: radial forearm (n = 65), fibula (n = 34), latissimus dorsi (n = 21), and serratus anterior muscle with rib bone free flap (n = 1). Total necrosis of the flap was found in four cases (two latissimus dorsi flaps and two fibular flaps). The free flap survival rate was 97.5%. Nineteen patients received radiotherapy before surgery, and none of them experienced flap failure. The mean operation time was 334 ± 83.1 min, and the mean ischemic time was 48.9 ± 12.7 min.

Conclusions

The success rate was reliable and comparable with previous studies. The success rate was not affected by radiation therapy. Free flaps can be safely used even after radiation treatment.

Multiple Thrombi during Microvascular Anastomosis Caused by Decreased Antithrombin Activity: A Case Report

With recent advances in microsurgical instruments and technique, microvascular anastomosis has become a universal surgical technique; however, thrombosis still presents in a number of cases. Tension, twisting, and compression to the anastomotic site are the main causes of thrombus; however, disorder of the coagulation-fibrinolysis system also need to be considered. To date, only few reports exist regarding thrombosis caused by disorder of coagulant system in microvascular anastomosis. Here we report our 3 cases in which multiple thrombus formation occurred intraoperatively caused by decrease of antithrombin (AT) activity. AT activity was measured twice a day after vascular anastomosis: after surgery and up to 3 days after surgery. Thrombosis was not observed in any of the 3 patients intraoperatively after the transfusion, or thrombosis was not observed in any of 3 patients intraoperatively after the transfusion or postoperatively, and no other complications were observed. In these 3 cases, the thrombus was not caused by technical error or other previously described factors. The observed intraoperative decrease in AT activity was thought to be caused by thrombus formation. It is important that microsurgeons are reminded that disorders of the coagulation-fibrinolysis system could cause thrombosis.

Towards standardization of training and practice of reconstructive microsurgery: an evidence-based recommendation for anastomosis thrombosis prophylaxis

BACKGROUND

Despite significant improvements in survival rates, free flap failures still occur even in experienced hands and are most commonly due to arterial or venous thrombosis. In the absence of an evidence-based guideline on the prevention of thrombosis, we reviewed the literature to assess the evidence base for commonly used interventions aimed at its prevention.

METHODS

A comprehensive literature search was performed using the following keywords "free flap" and microsurgery with "pre-operative screening," "prevention of thrombosis," "ketorolac," "heparin," "low molecular weight heparin," "aspirin," "dextran," and "statins."

RESULTS

Thirteen clinical studies were included in this review. No high-level evidence is available to support any perioperative or postoperative interventions aimed at reducing the risk of flap thrombosis.

CONCLUSIONS

Higher level studies are needed to investigate the clinical use of antithrombotic medications in microsurgery; however, given the small failure rates in modern practice, these will need to be large multicenter trials in order to reach sufficient power.Level of Evidence: Level III, risk/prognostic study.

Impact of diabetes on free flap surgery of the head and neck: A NSQIP analysis

OBJECTIVE

Diabetes is associated with microvascular pathology and may predispose patients undergoing microvascular surgery to complications. This study assesses diabetes as a risk factor for complications following free flap surgery of the head and neck.

PATIENTS AND METHODS

In this retrospective cohort study, data on free flap surgeries of the head and neck between 2005 and 2014 was collected from the National Surgical Quality Improvement Program (NSQIP) database. A propensity-matching algorithm (PSM) was used to equilibrate distribution of numerous covariates between the diabetic and nondiabetic cohorts. A sub-analysis was performed to examine the impact of insulin-dependency.

RESULTS

The initial dataset contained 2187 free flaps of the head and neck. After implementing PSM, a new population was created containing 506 total cases with 253 DM patients. The majority of cases were male and white. The matched cohort did not contain any demographics or comorbidities associated with DM. Complications significantly elevated in the DM group were severe bleeding (P = .046), postoperative ventilation greater than 48 hours (P < .001), and pneumonia (P < .048). In patients with insulin-dependent diabetes, reintubation (P = .005), cardiac arrest (P = .010), severe bleeding (P = .006), overall surgical complications (P = .015), and overall complications (P = .005) were significantly increased.

CONCLUSION

This study examines the impact of diabetes on postoperative complications following free flap reconstruction of the head and neck. Propensity score matching was utilized. Analysis of the PSM cohort suggests that diabetic patients have elevated rates of postoperative pulmonary complications. Additionally, patients with insulin-dependent diabetes have significantly elevated rates of medical and surgical complications.

Complications and thromboembolic events associated with tamoxifen therapy in patients with breast cancer undergoing microvascular breast reconstruction: a systematic review and meta-analysis

PURPOSE

Tamoxifen therapy is integral in the treatment of patients with hormone receptor-positive breast cancer. However, there is an association between tamoxifen and thromboembolic events. Flap and systemic thromboembolic events have devastating consequences in microvascular breast reconstruction. Currently, there are conflicting data on the association between tamoxifen therapy and thromboembolic complications for patients undergoing microvascular breast reconstruction. The objective of this study is to determine if perioperative tamoxifen therapy modifies the risk of complications and thromboembolic events for patients with breast cancer undergoing microvascular breast reconstruction.

METHODS

A comprehensive literature search was performed across six databases from January 2003 to February 2016. Pooled estimates and relative risk (RR) were calculated using a random-effects model, confounding was examined with meta-regression, and risk of bias was evaluated. Primary outcomes were thrombotic flap complications and total flap loss. Study quality was assessed using Downs and Black criteria.

RESULTS

Of 95 studies reviewed, 4 studies comprising 1700 patients and 2245 procedures were included for analysis. Compared to non-recipients, patients on tamoxifen were at increased risk of developing thrombotic flap complications (pooled RR 1.5; 95% CI 1.14-1.98) and total flap loss (pooled RR 3.35; 95% CI 0.95-11.91). There was no significant heterogeneity present in either outcome and no evidence of publication bias.

CONCLUSIONS

Perioperative tamoxifen therapy may increase the risk of thrombotic flap complications and flap loss for patients with breast cancer undergoing microvascular reconstruction. These findings further the ability of providers to make evidence-based recommendations in the perioperative management of patients with breast cancer.