The Optimal Sequence of Microvascular Repair during Prolonged Clamping in Free Flap Transfer:

Artery first and declamp it: A temporary revascularization method during microvascular anastomosis: A retrospective case series study

BACKGROUND

The optimal sequence of microvascular clamping during free flap transfer is yet to be established. Many surgeons are reluctant to perform temporary declamping and subsequent reclamping during microvascular anastomosis; however, we generally anastomose the artery first and temporarily declamp it before performing venous anastomosis to confirm arterial patency and ensure proper alignment of the flap veins. Herein, we aimed to retrospectively investigate the efficacy and safety of this temporary revascularization method in 126 patients who underwent microvascular head and neck reconstruction.

METHODS

A total of 127 free flaps were transferred, with the anterolateral thigh flap (49 flaps) being the most frequently used. The internal jugular vein was the most frequently used recipient vein and end-to-side anastomoses to it were performed in 112 patients.

RESULTS

Intraoperative reanastomosis was required because of arterial thrombosis in 5 cases (4.0%), arterial and venous thrombosis in 1 case (0.8%), injury to the flap artery distal to the anastomotic site in 1 case (0.8%), and venous twisting in 1 case (0.8%). Postoperatively, all the flaps survived without microvascular compromise.

CONCLUSIONS

Vascular kinking or twisting of the vascular pedicle is a major cause of free flap failure. However, it is difficult to place empty vessels accurately during clamping. Nonetheless, temporary revascularization engorges the flap vein before venous anastomosis and minimizes the risk of venous kinking and twisting. According to our results, reclamping did not increase the risk of arterial thrombosis.

Preparation of the Neck for Advanced Flap Reconstruction

Microvascular free tissue transfer has revolutionized the reconstruction of complex maxillofacial defects. These cases often necessitate a 2-teamed approach, with an ablative surgeon at the head and a reconstructive surgeon at a distant site for flap harvest. Careful attention to recipient vessel identification and preservation establishes the foundation for successful reconstruction. This article describes the surgical landmarks of the frequently utilized arteries and veins, vessel handling techniques, and general principles for the preparation of free tissue transfer recipient sites in head and neck reconstruction.

New Absorbable Microvascular Anastomotic Devices Representing a Modified Sleeve Technique: Evaluation of Two Types of Source Material and Design

The purpose of this study was to create a new absorbable vascular anastomotic coupler and evaluate the patency and degradation degree. Vascular anastomosis was performed in the jugular vein in 31 New Zealand white female rabbits. The coupler consisted of an inner and outer ring. One side of the jugular vein was passed through and overlapped the inner ring. The opposite side of the jugular vein overlapped the everted jugular vein on the inner ring. Then, the outer ring engaged with the inner ring and completed the anastomosis. The outer rings were also constructed with two shapes including an O-type that had no slit and a C-type with a slit on the outer ring of the O-type coupler to allows expandability of the diameter. A Phase I experiment was performed to evaluate the degradability of the source materials, including the poly (lactic-co-glycolic acid) (PLGA) and polycaprolactone (PCL) couplers. A Phase II experiment was performed to evaluate the patency and anastomosis time of the O-type PLGA and PCL couplers. A Phase III experiment was performed to evaluate the patency and anastomosis time of suture anastomosis (control) and the C-type PLGA coupler. The patency was determined by ultrasonography and open exploration. Histological analysis was performed to determine the degradability of the couplers. In Phase I, the PLGA couplers were completely degraded with good vascular wall remodeling at 8 months, while the PCL couplers demonstrated incomplete degradation. In Phases II and III, the anastomosis time was significantly shorter in the coupler groups than that in the control group. All of the coupler groups demonstrated complete patency of the anastomoses on ultrasonography. In Phase III, the C-type PLGA coupler also demonstrated patency and complete degradation at 8 months. PLGA is a suitable source material for absorbable couplers due to its fast degradability. We devised the O-shaped outer ring for the C-shaped outer ring to increase flexibility, which also demonstrated complete patency during the experimental period. Our absorbable microvascular anastomosis devices could provide rapid and reliable microvascular anastomosis without anastomotic failure.

Impacts of arterial ischemia or venous occlusion on vascularized groin lymph nodes in a rat model

BACKGROUND

Reported ischemia time of vascularized lymph nodes was 5 hours. This study investigated the effects of arterial ischemia and venous occlusion on vascularized lymph node function in rats.

METHODS

Bilateral pedicled groin lymph node flaps were raised in 27 Lewis rats. Femoral artery and vein were separated and clamped for 1, 3, 4, or 5 hour(s). Lymph node flap perfusion and drainage were assessed by laser Doppler flowmetry and indocyanine green lymphography. Histologic changes were assessed using hematoxylin and eosin stain, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL), and glutathione assays.

RESULTS

Perfusion units of 2.84 ± 1.41, 2.46 ± 0.64, 2.42 ± 0.37, and 2.01 ± 0.90 were measured in arterial ischemia groups, and 1.71 ± 0.45, 2.20 ± 0.98, 1.49 ± 0.35, and 0.81 ± 0.20 in venous occlusion groups after 1, 3, 4, and 5 hours of clamping, respectively. Lymphatic drainage showed mean latency periods of 5.33 ± 0.88, 9.00 ± 3.21, 10.00 ± 2.08, and 24.50 ± 11.50 seconds in arterial clamping groups, and 25.00 ± 3.61, 26.00 ± 3.06, 23.33 ± 4.41, and 152.00 ± 0 seconds in venous clamping groups, respectively. Severe medullary and cortical congestion and hemorrhage on histology and cell damage by glutathione levels and TUNEL assay were found after 4 hours of venous clamping.

CONCLUSIONS

Arterial ischemia and venous occlusion impact the function and viability of vascularized lymph node flaps differently. The critical venous occlusion time was 4 hours.

BioWeld® Tube and surgical glue for experimental sutureless venous microanastomosis

Background

The medial wall of mammalian veins is generally thin and fragile compared with the thick muscle seen in arteries. This makes venous microanastomoses time consuming and challenging. This study aimed to determine the feasibility and effectiveness of using the BioWeld® Tube in conjunction with a surgical glue (butyl-2-cyanoacrylate) in performing sutureless venous microanastomoses.

Methods

The feasibility and effectiveness of microvascular anastomoses in a rabbit jugular vein model were investigated in six animals, using the BioWeld® Tube in conjunction with butyl-2-cyanoacrylate surgical glue. Patency and tissue repair mechanisms at the anastomotic site were assessed 1 week after the procedure.

Results

All anastomoses remained patent at 1 week. Muscle necrosis occurred only in areas where the tissue was subject to the fold-and-bond procedure.

Conclusion

The study showed the feasibility and short-term effectiveness of the BioWeld® Tube in facilitating venous anastomoses.

Statins: a new pharmacological agent for free flap surgery?

Microvascular free tissue transfer has become the standard for reconstruction in head and neck oncological surgery. Several pharmacological agents have been used in order to increase the success rate of this surgery, but there is currently no consensus for an ideal drug. We review the literature concerning the complications encountered in free flap surgery related to the ischaemia-reperfusion injury and detail the effects of statins relevant to this endothelial dysfunction. Statins, because of their pleiotropic effects such as preservation of vascular tone, anticoagulation and anti-inflammatory properties, appear to be useful in free flap surgery. This study highlights the benefits of statins in order to increase the success rate and the quality of the free flap. They should be included in the perioperative strategy, especially in patients with cardiovascular risk factors. A protocol is presented.

Laser-assisted end-to-end BioWeld anastomosis in an ovine model

The BioWeld tube, an albumin-based exovascular stent, has been used for microsurgical anastomoses and compared to conventional sutures. The study presented investigated the potential of the BioWeld tube for vascular anastomosis in larger vessels. Laser-assisted BioWeld anastomoses were compared to conventional-sutured anatomoses of the carotid artery of Merino-x ewes. The BioWeld procedure resulted in 100% survival and 100% patency at 1 and 6 week post-operative periods, with no noticeable foreign body response. Sutured animals showed 100% survival and patency. The ischemic time for BioWeld anastomosis averaged 15 minutes compared with 10 minutes for sutures. This study indicates that the BioWeld tube is an easy to use anastomotic technique with equivalent success rates and comparable anastomotic times.