Intraoperative thrombolytic treatment of microarterial occlusion by selective rt-PA infusion

How do i salvage that flap?; An evidence-based primer on salvage techniques for head & neck microvascular free flaps

Interventional strategies for dealing with microvascular free flap failure are varied among institutions and even individual surgeons. This systematic review aims to identify the published methods for salvaging a failing free flap and provide surgeons with a comprehensive toolset for successful intervention. A title and abstract search of the PubMed, Embase, and Web of Science databases was performed. 1694 abstracts were screened by three reviewers according to Prisma guidelines. 62 full text articles meeting inclusion criteria detailed techniques which were separated into the categories of thrombectomy, thrombolysis, leech therapy, vascular fistula, and an "other" category outlining techniques which did not fit into the prior framework. Assessment of the efficacy of individual salvage techniques is limited due to limited empirical data, however, the approach to successful salvage should be based on timely identification of flap compromise, followed by the implementation of one or several of the aforementioned techniques.

Ex Vivo Machine Thrombolysis Reduces Rethrombosis Rates in Salvaged Thrombosed Myocutaneous Flaps in Swine

BACKGROUND

There is a risk for thrombotic complications (2 to 5 percent) associated with microsurgical reconstruction. Current thrombolytic therapy has a salvage rate between 60 and 70 percent, but it is afflicted by bleeding complications (2 to 6 percent). The use of machine perfusion for delivering thrombolytic agents is a new method that could potentially reduce these complications. In this article, the authors compared flap salvage outcomes comparing machine thrombolysis versus a manual flush with tissue plasminogen activator.

METHODS

Sixteen bilateral flaps (12 × 9 cm) were dissected from eight female Dutch Landrace pigs (70 kg). Thrombosis was induced in free rectus abdominis flaps by clamping the pedicle's veins for 2 hours. Flaps were either thrombolysed with 2 mg tissue plasminogen activator (1 mg/ml) during 2 hours of machine perfusion (perfusion group; n = 8) or injected intraarterially (manual group; n = 8) before replantation. Near-infrared fluorescence angiography was used to confirm thrombus formation and to assess tissue perfusion; muscle biopsy specimens were analyzed for ischemia/reperfusion injury directly after thrombolysis and 15 hours after replantation.

RESULTS

A higher incidence of secondary thrombosis was seen in the manual group compared to the perfusion group ( n = 6 versus n = 0, respectively; p < 0.001), resulting in two complete flap failures. Fifteen hours after replantation, mean fluorescence intensities were 13.0 (95 percent CI, 10.1 to 15.8) and 24.6 (95 percent CI, 22.0 to 27.2) in the perfusion and manual group, respectively ( p < 0.001), and mean muscle injury scores were comparable, measuring 7.5 ± 1.5.

CONCLUSION

Two hours of machine thrombolysis of compromised flaps in a porcine model showed higher salvage rates compared to a manual injection with tissue plasminogen activator and reduced the incidence of secondary thrombosis.

CLINICAL RELEVANCE STATEMENT

Using machine perfusion systems for ex vivo thrombolysis provides the benefits of local treatment of a composite tissue without the risk of systemic complications and may improve salvage rates and reduce the incidence of secondary thrombosis.

Sauvetage des revascularisations digitales par administration intra-artérielle de fibrinolytiques

At the end of the seventy, we saw the reconstructive microsurgery developed to such an extent that it became a new and an independent surgical specialty. The development of the microsurgical instrumentation and the description of the surgical anatomy allowed the application of this technology to the most complex plastic reconstructions and particularly to the replantation of the amputated digits, especially the very distal digital amputations. Nowadays, the indications of digital replantation are well-defined according to numerous parameters conditioning the anatomical result and the functional outcome. It is well-known that the replantation of the amputated digit should be realized as soon as possible with optimal conditions of digital hibernation during the patient transport. In spite of that technical progress, the failure rate is still relatively important. The causes are sometimes recognizable and connected to technical defection, such as a non permeable vascular anastomosis, bad hemodynamics conditions or an insufficient anticoagulation, while in certain cases, the digital ischemia occurs in spite of permeable and technically successful arterial anastomosis. We then consider a "no reflow phenomenon". It corresponds to the constitution of vascular microthrombi which will block the arteriolar network. Those microthrombi are inaccessible to the microsurgical techniques and their treatment remains medical by intra-arterial infusion of antithrombotic agents. Through our series of fifteen digital replantations, having suffered a "no reflow phenomenon", we are going to present the fibrinolytic protocol we used and the promising results we obtained. All our patients were victims of traumatisms associating avulsions and crush injuries mechanisms. The conditions of preservation of the amputated digits were all quite unfavourable: 1) the amputated digit soaked in water in 5 cases; 2) the amputated fingers underwent a long-term "warm ischemia" in three cases, going up to 13 hours for one of them; 3) the amputated digits were completely frozen in six cases; 4) and one amputated finger was correctly hibernated but for too long a period (8 hours). The signs of ischemia appeared very prematurely in the first minutes after the microvascular revascularisation in ten cases, and in average within three hours postoperatively in the other five cases, with extreme cases going from 2 up to 6 hours. As soon as the diagnosis of "no reflow phenomenon" was confirmed, an intra-arterial catheter was fixed. The radial axis was chosen as the arterial infusion way and approached at the level of the pulse groove. The antithrombotic protocol included a flash of 50,000 UI of urokinase, 36 ml of lidocaïne 1% and 40 mg of enoxaparine, followed by an electric syringe infusion the first six hours with 150,000 UI of urokinase, 36 ml of lidocaïne 1% and 40 mg of enoxaparine at 6 cc/h speed. The urokinase was then interrupted but the intra-arterial infusion maintained with 72 ml of lidocaïne 1% and 80 mg of enoxaparine for 24 hours, at a 3 cc/h speed, and this for ten days. In 12 cases, the "no reflow phenomenon" was able to be raised and the digital vascularization restored. The success rate is very encouraging (80%) and it turns this protocol into a precious ally of the digit replantation microsurgery and an effective therapeutic means way against the "no reflow phenomenon".

Salvage of free flaps after venous thrombosis: Case report

Venous thrombosis of a free flap is a serious complication in microsurgery. Several agents with the ability to dissolve an occluding thrombus exist. Recombinant tissue plasminogen activator (rt-PA) seems the most effective. We present our experience with a procedure that was successful in elimination of the occluding thrombus in two patients.

Late salvage of a free TRAM flap

We present the case of a patient with arterial thrombosis of a free TRAM flap 11 days after surgery. Initial salvage involved thrombectomy through an arteriotomy using a Fogarty catheter. Subsequent return to the operating theatre was necessary because of further vascular compromise. Thrombectomy was combined with flap thrombolysis and anticoagulation, and the flap remained viable at 6 months. Although rates of successful salvage vary, the literature indicates that flaps are rarely saved if signs of compromise present later than 2 days postoperatively. This case demonstrates that aggressive salvage may be successful even in cases of 'late' vascular compromise.

Microsurgical repair after crush-avulsion injury of the femoral vein in rats: prevention of microvascular thrombosis with recombinant human tissue-type plasminogen activator (rt-PA)

Vein thrombosis is often encountered in microsurgery, especially in the case of crush-avulsion injuries. The aim of this study was to investigate the effect of systemic administration of recombinant tissue-type plasminogen activator (rt-PA) on the patency of the femoral vein of the rat, which had previously sustained a crush-avulsion injury. The study consisted of 3 groups of male Wistar rats, 20 animals each. A standardized crush-avulsion injury model was used. After microvascular repair of the femoral vein, the animals received either normal saline (group A), heparin 100 U/kg body weight (group B), or rt-PA 3.5 mg/kg body weight (group C) systemically. Patency tests were performed at 20 minutes, 48 hours, and 1 week after blood flow reestablishment. According to our results, the patency rate of the rt-PA group was significantly higher than in both the control and heparin groups.

Thrombolytic therapy: what is its role in free flap salvage?

Thrombolytic agents have been demonstrated to improve free flap salvage in animal models. However, clinical evidence regarding their efficacy has been scant. The authors reviewed their experience with flap salvage using thrombolytic therapy in 1,733 free flaps from February 1990 to July 1998. Patients with intraoperative pedicle thrombosis were excluded from this review. Forty-one of the 55 free flaps that were reexplored emergently were identified as having pedicle thrombosis. Of these 41 flaps, 28 free flaps were salvaged (flap salvage group, 68%) and 13 free flaps failed (flap failure group, 32%). Thrombolytic therapy (urokinase in 7 patients, tissue plasminogen activator in 1 patient) was used in six flaps in the flap salvage group and two flaps in the flap failure group. Statistical analysis demonstrated no difference between the two groups with regard to thrombolytic therapy. There was also no difference between the two groups with regard to use of systemic heparin (100-500 U per hour) at the time of pedicle thrombosis or with regard to whether Fogarty catheters were used. Smoking, preoperative radiotherapy, and the use of interpositional vein grafts during initial flap reconstruction had no impact on the outcome of flap salvage. The flap salvage group was reexplored at a mean of 1.5 days compared with the flap failure group, which was reexplored at a mean of 4.2 days (p = 0.007). Early detection of pedicle thrombosis remains the most important factor in the salvage of free flaps. Although these numbers are small and definitive statements cannot be made, the role of thrombolytic agents in free flap salvage requires further clinical evaluation.

Microvascular repair with 1-mm polytetrafluoroethylene (PTFE) grafts: effect of recombinant tissue-type plasminogen activator (rt-PA) on the patency rate and healing process

The present study assesses the effect of recombinant tissue-type plasminogen activator (rt-PA) on the patency rate and healing process of microvascular polytetrafluoroethylene (PTFE) grafts. Wistar rats were used, divided into four groups of 25 animals each. After dissection of the carotid artery a segment of the vessel, 1 cm long, was resected and replaced by equal length graft. Two different type fibril length (30- or 60-microm) grafts of the same wall thickness (0.18 mm) were used. Normal saline or 3 mg/kg of body weight of rt-PA was applied locally in each group of different fibril length grafts. Patency tests were performed at 15 min and 4 weeks after blood flow was reestablished. All grafts were harvested and examined histologically. The results showed that local application of rt-PA improves patency statistically significantly in both types of fibril length grafts. Patency in 60-microm fibril length grafts was statistically significantly higher than that of 30-microm fibril length grafts, whether rt-PA was used or not. The use of rt-PA had no influence on the healing process of either type of graft.

Microvascular repair following a modified crush-avulsion injury in a rat model: effect of recombinant human tissue-type plasminogen activator on the patency rate

The failure rate of replantations following a crush-avulsion type injury is high. This study has been designed to reproduce an effective standardized crush-avulsion injury model to the femoral artery of the rat and evaluate the antithrombotic efficacy of systemic intravenous administration of recombinant human tissue-type plasminogen activator (rt-PA). The crush-avulsion injury was reproduced by using a bulldog clamp and two hemostats and followed by microvascular repair. The animals were divided into three groups of 20 rats each and received either normal saline, heparin 100 U/kg body weight, or rt-PA 3.5 mg/kg body weight intravenously. Patency tests were performed 20 min and 48 h after blood flow reestablishment. Results showed that this experimental crush-avulsion injury model ensures low patency in the control group, whereas systemic rt-PA administration improves the patency rate statistically significantly compared to control and heparin groups at both 20 min and 48 h postrevascularization.

Experimental prevention of free flap thrombosis. II: Normovolemic hemodilution for thrombosis prevention

A microvascular free flap failure model consisting of raising an epigastric groin flap on the femoral pedicle, while cutting the femoral artery, twisting it around the femoral vein and resuturing it, has been previously described. As it was being evaluated, normovolemic hemodilution as a means to prevent thrombosis was simultaneously assessed using an additional experimental group. Twenty percent of the blood mass of each rat was taken and replaced with a hydroxyethyl starch solution immediately before surgery. Only 14 out of 20 anastomoses presented with thrombosis (13 venous and one mixed), as opposed to 19 out of 20 animals operated on without hemodilution (P< 0.05). Normovolemic hemodilution appears to be an effective method of reducing microvascular free flap failure.

Local recombinant tissue plasminogen activator (rt-PA) thrombolytic therapy in microvascular surgery

Vascular thrombosis remains a dreaded complication of any microvascular procedure, be it composite tissue transfer or replantation of amputated limbs or parts. Despite the tremendous advances in microvascular-related technologies and the accumulated surgical skills, failures caused by occlusion of anastomosed vessels remain a continuous source of frustration to all microsurgeons alike. Several anticoagulation and antiplatelet protocols have been proposed to be used in conjunction with microvascular surgery. More recently, thrombolytic drugs such as urokinase, streptokinase, and thrombolysin have been introduced, yet their systemic effect on hemostasis remains an undesirable side effect. We present our experience with local intra-arterial, intravenous, and soft-tissue injection of recombinant tissue plasminogen activator rt-PA in replantation surgery in three consecutive patients. Arterial thrombi are managed by intra-arterial rt-PA infusion with the catheter placed proximal to the arterial anastomosis. Venous thrombi are best lysed by infusing rt-PA in an engorged vein of the replanted limb. In replanted digits, direct intravenous infusion is not possible. In such situations, injection of rt-PA in the pulp soft tissues may result in successful salvage. We believe this agent also has a role in microvascular composite tissue transfer in preventing free flap failures as well as in salvaging failing flaps.