Microsurgery principles Flashcards
A 45-year-old woman undergoes reconstruction of the right breast with a deep inferior epigastric artery perforator flap. Postoperatively, the flap shows signs of ischemia and is reexplored. During flap salvage, which of the following agents should be administered to inactivate thromboxane?
A) Aspirin
B) Dextran
C) Heparin
D) Hirudin
E) Streptokinase
The correct response is Option A.
Aspirin, or acetylsalicylic acid, inhibits the enzyme cyclooxygenase. Cyclooxygenase ordinarily functions to form multiple compounds from arachidonic acid, including thromboxane and prostacyclin. Thromboxane is a platelet aggregator and vasoconstrictor. Prostacyclin is also a platelet aggregator. By decreasing formation of these compounds, aspirin acts as an anticoagulant.
Dextran is a polysaccharide whose mechanism of action is thought to involve decreasing platelet aggregation by altering the electric charge of platelets, as well as by decreasing blood viscosity. Dextran also acts as a volume expander.
Heparin is a glycosaminoglycan that binds to antithrombin III and enhances its ability to inactivate thrombin (which ordinarily converts fibrinogen to fibrin), as well as clotting factors IX, X, XI, and XII. Heparin may also additionally decrease thrombosis by causing nitric oxide-mediated vasodilation.
Hirudin is derived from the medicinal leech Hirudo medicinalis and functions by directly inhibiting thrombin, in contrast to heparin, which requires the antithrombin III cofactor.
Streptokinase is a thrombolytic agent that functions by activating plasminogen and its conversion to plasmin. In turn, plasmin breaks down fibrin into fibrin degradation products.
A 16-year-old boy develops a severe left first web space contracture 8 months after undergoing skin grafting for a soft-tissue avulsion injury. At the time of contracture release, a pedicled fasciocutaneous flap is planned for coverage of the soft-tissue defect. On the basis of the preoperative markings for the flap in the photographs shown, the flap pedicle is located between which of the following muscles?
A) Brachioradialis and extensor carpi radialis longus
B) Brachioradialis and flexor carpi radialis
C) Extensor digiti minimi and extensor carpi ulnaris
D) Extensor digiti minimi and the extensor digitorum communis
E) Extensor digitorum communis and extensor carpi radialis brevis
The correct response is Option C.
The photograph illustrates the markings for a reverse posterior interosseous artery (PIA) flap. The reverse PIA flap is a thin, pliable fasciocutaneous flap that can provide reliable coverage of soft-tissue defects involving the dorsal hand, metacarpophalangeal joints, and first web space. Some surgeons report success using this flap for coverage of palmar wounds and soft-tissue injuries of the thumb as well.
Perfusion of the flap is based on retrograde flow through the posterior interosseous artery, which sends septocutaneous perforators to the overlying skin. The axis of the flap can be marked corresponding to a line between the lateral epicondyle and the radial aspect of the ulnar styloid. The location of the posterior interosseous artery pedicle is between the extensor digiti minimi and the extensor carpi ulnaris. Retrograde perfusion through the flap relies on an intact communication of the PIA with the dorsal branch of the anterior interosseous artery, which is present in nearly all cases. This anastomosis is located 2 cm proximal to the radial aspect of the ulnar styloid; therefore, it corresponds to the pivot point of the flap. One of the advantages of this flap is that it does not require sacrifice of a major arterial source of blood to the hand.
The other responses do not correctly describe the location of the PIA. Of note, the interval between the brachioradialis and the flexor carpi radialis represents the location of the radial artery fasciocutaneous flap pedicle.
A 60-year-old man with a history of smoking requires near total mandibular reconstruction with a free vascularized fibula. During dissection of the flap, the surgeon should encounter which of the following muscles prior to incising the interosseous septum from an anterior approach?
A) Extensor hallucis longus
B) Flexor hallucis longus
C) Soleus
D) Tibialis anterior
E) Tibialis posterior
The correct response is Option A.
Just prior to incising the interosseous septum, the surgeon would be in the anterior compartment of the leg. The muscle lying just anterior to that septum would be the extensor hallucis longus. The tibialis anterior is medial to the plane of dissection for a fibula flap. The flexor hallucis longus and tibialis posterior are located in the deep posterior compartment while the peroneus brevis is found in the lateral compartment. The soleus is located in the superficial posterior compartment.
A 16-year-old boy has right hemifacial hypoplasia secondary to radiation therapy of an orbital sarcoma when he was an infant. Right hemifacial soft-tissue augmentation with a partially buried omental free flap is performed. Photographs are shown. Which of the following is the most sensitive method of monitoring perfusion of this flap and detecting early anastomotic thrombosis?
(A) Clinical observation of the flap
(B) Bedside duplex ultrasonography of the gastroepiploic vessels
(C) Quantitative fluorometry of the flap with Wood’s lamp
(D) External Doppler probe monitoring of the gastroepiploic vessels
(E) Implantable Doppler monitoring of the gastroepiploic vein
The correct response is Option E.
Buried free flaps and flaps without a cutaneous component can be difficult to monitor regarding postoperative flap perfusion. Early detection of anastomotic thrombosis is critical in successful salvage and revision of the failing free flap. Although color, temperature, and turgor can be used to monitor free flap perfusion, the omentum does not contain a skin paddle to help with clinical examination. An external handheld Doppler probe can identify arterial and venous signals, but correlation with the actual pedicle can be difficult to determine. Duplex ultrasound examination of the neck provides a great deal of information, such as direction of flow, alterations in flap resistance, and increased pedicle turbulence, but such imaging is not immediately available and requires the expertise of a vascular technologist. Injection with fluorescein and observation with a Wood=s lamp can assist with the qualitative assessment of flap perfusion if a skin paddle exists and can be monitored. Implantable venous Doppler monitoring will identify problems with both the arterial and venous pedicle.
A recent clinical report of 260 vascular microanastomoses with an implantable Doppler probe yielded six false-positive results and eight true-positive results. The overall free flap success rate was 99%; the reexploration rate was 8% and the salvage rate was 83%, partly due to the early detection of anastomotic thrombosis.
Doppler ultrasonography has been used to document changes in arterial blood flow after free tissue reconstruction in reconstruction of the head and neck. This modality can be helpful as an adjunctive tool in assessing flap perfusion but currently does not provide cost-efficient, continuous monitoring necessary to detect early anastomotic changes.
The photograph below shows the patient after successful reconstruction of hemifacial hypoplasia and after free tissue transfer of the omentum and secondary facelift and browlift, with intact facial nerve function.
A 48-year-old woman underwent delayed right breast reconstruction with a DIEP flap in which the internal mammary vessels were used as the recipient vessels. One day after surgery, the skin paddle of the free flap appears congested and Doppler examination of the perforator shows diminished arterial signal. Emergent operative exploration shows that the venous pedicle is thrombosed. Local infusion of which of the following agents is most effective in reestablishing circulation?
A ) Dextran
B ) Heparin
C ) Lidocaine
D ) Milrinone
E ) Tissue plasminogen activator
The correct response is Option E.
Tissue plasminogen activator (TPA) catalyzes the conversion of plasminogen to plasmin. Unlike the other previously used thrombolytic agents, urokinase and streptokinase, TPA is more specific because its efficacy is enhanced by the presence of fibrin. In theory, this results in fewer bleeding complications than the less specific thrombolytic agents, which are no longer available in many hospital pharmacies.
Most large free flap series report that venous thrombosis is more commonly encountered than arterial compromise. Free flap monitoring is the most important aspect of free flap care with a low threshold for reexploration critical to the success of free flap salvage. Once thrombosis of a vascular pedicle is observed and the anastomosis taken down, thrombectomy followed by thrombolysis can often result in flap salvage.
Intravenous dextran and heparin have been used for platelet inhibition and anticoagulation to improve free flap patency rates. Heparin irrigation locally is used to prepare vessels for anastomosis. Lidocaine and papaverine are used locally to vasodilate vessels. Milrinone is a systemic vasodilator but has not been shown to improve free flap patency.
Which of the following is NOT a proposed mechanism of action of dextran used in microsurgery?
(A) Decreased factor VIII and von Willebrand factor
(B) Increased alpha-2 antiplasmin
(C) Increased electronegativity
(D) Structural modification of fibrin
(E) Volume expansion
The correct response is Option B.
Although the benefits of dextran 40 used during microsurgery are controversial, this agent is still used frequently. Dextran decreases factor VIII and von Willebrand factor, resulting in a decrease in platelet function. It is thought to increase the electronegativity of platelets in the endothelium, which prevents platelet aggregation, and is also thought to modify the structure of fibrin, increasing its susceptibility to degradation. It alters the rheologic properties of blood and acts as a volume expander.
Dextran inhibits, not increases, alpha-2 antiplasmin, leading to a subsequent activation of plasminogen.
Because dextran has the potential for antigenicity, a test dose of 20 mL of 150 mg/mL solution is typically administered one to two minutes before infusion.
A 43-year-old woman is evaluated because of lymphedema of the lower extremities. She demonstrates pitting edema, which does not improve with limb elevation. Her skin feels otherwise normal, with no evidence of fibrotic change. Which of the following International Society of Lymphology stages best describes this patient’s lymphedema?
A) 0
B) 1
C) 2
D) 3
The correct response is Option C.
Lymphedema results from congenital or acquired dysfunction of the lymphatic system. It results from changes to the lymphatic vessels, including ectasia and valve dysfunction. This results in reflux of lymphatic fluid into the interstitial space. Lymphatic fluid accumulation leads to chronic inflammation, extracellular matrix remodeling and fibrosis, adipose tissue differentiation, progressive fibrosis/sclerosis, and eventual obliteration of the lymphatic vessel lumen. Over time, accumulation of interstitial lymphatic fluid causes subcutaneous fibroadipose production.
Lymphedema is a chronic condition that slowly worsens over time. It progresses through four stages. Stage 0 indicates a clinically normal extremity but with abnormal lymph transport (identified via lymphoscintigraphy). Stage 1 demonstrates a relative accumulation of fluid high in protein content, which improves with limb elevation. Pitting may occur. Stage 2 represents pitting edema that does not resolve with elevation, but no evidence of fibrotic skin changes. Late in Stage 2, the limb may not pit as excess fat and fibrosis begins. Stage 3 describes fibroadipose deposition and fibrotic skin changes.
The presence of dermal backflow on contrast-enhanced imaging of the lymphatic system is diagnostic for lymphedema, and the severity and distribution of this backflow correlate closely with the pathologic condition of the lymphatic vessels. Indocyanine green fluorescent lymphography enables detailed dynamic functional evaluation of the superficial lymphatic system and can also be used for intraoperative lymph node mapping for vascularized lymph node transplantation.
A 38-year-old woman undergoes bilateral breast reconstruction using microvascular free tissue transfer from the abdomen. The patient is evaluated 8 hours later because the right breast flap appears mottled and engorged. Administration of which of the following is CONTRAINDICATED in this patient?
A) Heparin irrigation to the flap vessels
B) Papaverine to the flap vessels
C) Systemic heparin
D) Systemic thrombolytics
E) Thrombolytics to the flap vessels
The correct response is Option D.
Heparin may be used locally or systemically during flap salvage attempts in an effort to encourage further propagation of clot and irrigate existing thrombus. Papaverine and thrombolytic agents are used locally on or within the flap vessels, but not systemically due to concern for systemic complications.
A 45-year-old woman with a history of systemic lupus erythematosus requires a free flap reconstruction of her right lower extremity. She has never had a thrombotic event. She is on corticosteroids for collagen vascular disease. Which of the following perioperative measures is most appropriate?
A) Intraoperative and postoperative anticoagulation
B) Intraoperative anticoagulation alone
C) Preoperative and postoperative aspirin therapy
D) Preoperative hypercoagulability workup
E) Preoperative vitamin A therapy
The correct response is Option D.
The most appropriate management would be to get a formal hematology consult and anticoagulation workup prior to surgery. Collagen vascular diseases target connective tissues and have multiorgan manifestations secondary to deposition of antigen-antibody complexes. Affected patients are intrinsically prone to thrombosis from the inflammation of the connective tissue disorder itself and the synergistic effect of having increased chances of having concurrent hypercoagulability risk factors such as anticardiolipin or lupus anticoagulant.
Therefore, in this patient population with the threat of vascular compromise, it is most prudent to perform preoperative hematologic evaluation, especially if they exhibit a history of previous clotting and flap failure. As a more prudent measure, all of these patients should have a detailed hypercoagulability evaluation, including a detailed history and hematology consultation with a laboratory panel looking for hypercoagulability factors. If positive, steps should be taken perioperatively to decrease the risk of thrombotic complications, and chemical anticoagulation should be considered, but if negative with no history of previous thrombotic complications, then no added chemical anticoagulation is needed. Studies have not shown an increase in thrombotic flap failures in such patients, despite their intrinsic risk of thrombosis.
Aspirin therapy has not been shown to decrease flap loss rates. Vitamin A is indicated in this patient, not to decrease thrombotic flap loss rates, but rather to counteract the immunosuppressive medications.
A 51-year-old woman is undergoing free flap breast reconstruction. Following anastomosis, the patient sustains a venous thrombotic event, and the decision is made to flush the flap with tissue plasminogen activator (tPA). Which of the following is the primary mechanism of action of tPA as used in this scenario?
A) Antithrombin III activation
B) Fibrinolysis
C) Inhibition of platelet aggregation
D) Protein C activation
E) Prothrombin cleavage
The correct response is Option B.
During microsurgical procedures, the normal clotting mechanism may disrupt flow at the anastomosis. Multiple medications are available to limit clotting following the failure of an anastomosis. However, only certain medications are fibrinolytic and actively break down clots, whereas others limit the formation of further clots. Tissue plasminogen activator (tPA) is one such fibrinolytic agent, which increases the cleavage of the zymogen, plasminogen, to its active form, plasmin. Plasmin is directly fibrinolytic.
Prothrombin cleavage, to form activated thrombin, is primarily facilitated by factor X and results in increased thrombogenesis. Aspirin is a common drug that inhibits platelet aggregation, but this does not have a fibrinolytic effect and is not the mechanism by which tPA functions. Antithrombin III activation is the main mechanism of action of heparin, which limits multiple points in the thrombosis pathway. This medication is not fibrinolytic. Activated protein C is a powerful anticoagulant that inhibits both factors V and VIII in the coagulation cascade. Use of a recombinant protein C has been used in septic shock, but its benefits remain controversial. tPA does not function by protein C activation.
A 50-year-old woman undergoes reconstruction of a postburn neck contracture with a free anterolateral thigh flap. On postoperative day 2, the flap is explored for vascular compromise and is successfully salvaged. On postoperative day 3, the flap suffers vascular compromise and is explored again. During the operation, the anastomoses are revised using vein grafts. Which of the following factors is most strongly associated with unsuccessful flap salvage in this patient?
A) Anatomic site
B) Multiple reexplorations
C) No use of anticoagulants
D) No use of thrombolytic agents
E) Postoperative day of initial reexploration
The correct response is Option B.
The need for multiple reexplorations has been found to be a predictor for unsuccessful free flap salvage.
Free flap reconstruction of the breast has been associated with higher flap survival rates than other anatomic areas, such as the head and neck and extremities.
Higher free flap survival rates have been observed when vascular compromise occurs earlier in the postoperative period (postoperative days 0 to 2) compared with later.
Anticoagulants, such as heparin, are sometimes used during free flap salvage attempts. However, their use has not been found to impact flap survivability. The same has been found with regard to thrombolytic agents, such as tissue plasminogen activator.
A 43-year-old right-hand–dominant man presents with Volkmann flexion contractures of the right hand after sustaining a severe burn injury to the right volar forearm. Reconstruction with an innervated gracilis free myocutaneous flap is planned. During flap elevation, the vascular pedicle is identified approximately 7 cm distal to the pubic symphysis between which of the following structures?
A) Adductor longus and adductor magnus muscles
B) Adductor magnus and vastus medialis muscles
C) Sartorius and adductor longus muscles
D) Semimembranosus and sartorius muscles
E) Vastus medialis and semimembranosus muscles
The correct response is Option A.
The innervated gracilis muscle flap is a useful functional reconstructive tool. Its tendinous distal third makes this flap an attractive choice for finger flexor or extensor tendon reconstruction. The dominant supply to the vascular pedicle to this flap arises from the profunda femoris artery, and the muscle is innervated by the obturator nerve. During harvesting of the flap, the nerve and vascular pedicle can be reliably identified between the adductor longus and adductor magnus muscles, approximately 7 cm distal to the pubic symphysis. When a skin paddle is included, it is recommended to design the skin paddle within the proximal two thirds of the muscle, because skin necrosis is a greater concern over the distal third of the muscle.
A 57-year-old woman undergoes microsurgical breast reconstruction using a muscle-sparing transverse rectus abdominis musculocutaneous (MS-TRAM) flap. Near-infrared spectroscopy (NIRS) is used to monitor the flap in the postoperative setting. NIRS measures which of the following parameters?
A) Arterial oxygen saturation (SaO2)
B) Mixed venous oxygen saturation (SvO2)
C) Partial pressure of oxygen (PaO2)
D) Peripheral oxygen saturation (SpO2)
E) Tissue oxygen saturation (StO2)
The correct response is Option E.
Near-infrared spectroscopy (NIRS) is a noninvasive modality that allows continuous monitoring of tissue oxygenation and perfusion. It measures relative changes in the concentration of oxygenated and deoxygenated hemoglobin. Tissue oxygen saturation (StO2) is the percentage of hemoglobin in tissue that is oxygenated. Since StO2 measures oxygen saturation in the vascular bed of tissue, it measures both venous and arterial saturation and, thus, reflects both oxygen delivery and consumption. This provides a good surrogate for tissue perfusion. Peripheral capillary oxygen saturation (SpO2), measured by pulse oximetry, measures arterial oxygen saturation, which may not reflect perfusion. Arterial (SaO2) and mixed venous oxygen saturation (SvO2) as well as the partial pressure of oxygen (PaO2) are measured directly from blood and are indicative of systemic rather than local tissue oxygenation.
A 48-year-old woman had delayed microsurgical breast reconstruction. Two hours after surgery, the patient has swelling of the breast and increased drain output. On examination at the bedside, the flap appears purple with capillary refill time of 1 second. Heart rate is 70 bpm, blood pressure is 110/60 mmHg, and most recent hematocrit is 28%. An arterial signal is identified in the skin paddle with a handheld Doppler. Which of the following is the most appropriate next step in management?
A) Application of nitroglycerin paste
B) Operative reexploration
C) Pinprick of the flap
D) Placement of leeches
E) Streptokinase therapy
The correct response is Option B.
The patient described has venous insufficiency after microsurgery and the next step in management is emergent reexploration in the operating room.
Multiple studies confirm that earlier reexploration improves flap salvage rates. The rate of reexploration ranges from 6 to 14%; in these cases, the flap salvage rate ranges from 36 to 94%. Time of return to the operating room is associated with flap salvage. The majority of microvascular complications occur in the first 48 hours, and the majority of these complications are due to venous thrombosis. Common presenting signs include a purple or blue skin discoloration, brisk capillary refill, edema, oozing, or hematoma.
Release of sutures and pinprick of a flap and application of nitroglycerin paste can improve venous congestion in pedicled flaps, but do not obviate the need for reexploration in a microsurgical flap. Placement of leeches is a salvage option and often used when intraoperative maneuvers are unsuccessful. Streptokinase has been described for use in cases where a clot is found within the vascular system, but this should be reserved for use during reexploration, not before.
A 48-year-old woman undergoes delayed reconstruction of the right breast with a deep inferior epigastric artery perforator (DIEP) flap. Medical history includes failed tissue expander–based right breast reconstruction because of infection 5 months ago. On postoperative day 5, the patient comes to the emergency department with a swollen, purple flap, which she noticed after showering. The venous anastomosis is revised and flap thrombolysis is performed with tissue plasminogen activator, successfully restoring flap perfusion. Which of the following clinical factors is LEAST likely to increase this patient’s risk of thrombotic flap complications?
A) Antiphospholipid syndrome
B) Antithrombin deficiency
C) BRCA1 or BRCA2 genetic mutation
D) Factor V Leiden mutation
E) Perioperative tamoxifen therapy
The correct response is Option C.
This patient has developed a late venous thrombosis and may be predisposed to a hypercoagulable state. The BRCA1 and BRCA2 genes are tumor suppressor genes involved in DNA repair. Mutations in these genes dramatically increase a woman’s risk of developing breast and ovarian cancer over her lifetime, and are the most common cause of hereditary forms of breast and ovarian cancer. But BRCA genetic mutations do not appear to increase the risk of blood clots over baseline and would be unlikely to contribute to this patient’s condition.
The other options are incorrect because each carries higher than average risk of blood clots. Perioperative tamoxifen therapy increases the risk of thromboembolic events in general and for flap complications and flap loss during microvascular breast reconstruction in particular. Tamoxifen is an estrogen receptor antagonist and is used both to treat and prevent breast cancer. Some authors recommend cessation of tamoxifen at least 14 days prior to microvascular breast reconstruction to minimize thrombosis risk.
Factor V is a protein involved in the coagulation cascade. Factor V Leiden mutation is an inherited condition that confers a hypercoagulable state, increasing the risk of thrombotic complications.
Antithrombin III is a protein similarly involved in anticoagulation. Deficiency may be either inherited or acquired, and it confers an increased risk of venous thrombotic events.
Antiphospholipid syndrome is an acquired autoimmune disorder which also confers a hypercoagulable state. Venous or arterial thrombosis, as well as fetal loss, are characteristic of this disorder. Some patients will have an associated autoimmune disease, such as systemic lupus erythematosus.
A 54-year-old woman undergoes breast reconstruction using a deep inferior epigastric artery perforator (DIEP) flap. Arterial thrombosis is noted after performing the microanastomosis. Which of the following is more likely to occur with local administration of tissue plasminogen activator (tPA) as an adjunct to revision microanastomosis as compared with revision microanastomosis alone (without tPA)?
A) Decreased flap salvage rate
B) Decreased incidence of fat necrosis
C) Increased flap salvage rate
D) Increased incidence of fat necrosis
E) Increased incidence of operative hematoma
The correct response is Option B.
Administration of tissue plasminogen activator (tPA) during revision of a microanastomosis has a decreased rate of subsequent fat necrosis. The suspected mechanism of action is thrombolysis of distant “shower” emboli in the microvasculature.
The administration of tPA as an adjunct to microanastomotic revision has no effect on flap salvage rates. In addition, there is no change in hematoma risk since the dose is low (2 mg) and is usually injected directly into the flap artery, which is maintained locally in the flap. Only if larger doses of tPA were given systemically would there be a risk of operative hematoma.
An 18-year-old man is brought to the emergency department for thumb replantation. After an uneventful microsurgical anastomosis of the digital arteries and veins, papaverine is applied to the vessels. This medication works as a vasodilator through which of the following mechanisms?
A) Blocking calcium channels
B) Decreasing platelet aggregation
C) Inactivating thrombin and factor Xa
D) Inhibiting glycoprotein IIb/IIIa
E) Inhibiting phosphodiesterase
The correct response is Option E.
Papaverine is a phosphodiesterase inhibitor and is a commonly used vasodilating agent in microsurgery. It is administered as a liquid, directly to the adventitia of blood arteries, leading to vasodilation. The proposed mechanism of action of papaverine is by induced increase in cyclic adenosine monophosphate (AMP) levels, causing smooth muscle relaxation in the vessels. It is this mechanism of papaverine that has also led to its use for treatment of cardiac and neurovascular vasospasm.
Nifedipine is another common topical vasodilator, which is a calcium channel blocker. The remaining choices are all used to prevent clotting. Glycoprotein IIb/IIIa inhibitors are antiplatelet agents along with aspirin. Heparin inactivates thrombin and factor Xa through an antithrombin dependent mechanism.
A 42-year-old woman presents with a Gustilo Type IIIB open tibial fracture with a large area of soft-tissue loss. Rectus abdominis free flap reconstruction is planned. CT angiography shows a patent posterior tibial artery; however, the peroneal and anterior tibial vessels are not suitable for use because they do not traverse past the level of the fracture. Compared with end-to-end anastomosis, which of the following is the main advantage to using end-to-side arterial anastomosis in this scenario?
A) Allows anastomosis in zone of injury
B) Decreases ischemia time
C) Facilitates visualization
D) Minimizes kinking of vessels
E) Preserves distal blood supply
The correct response is Option E.
In this clinical scenario, the patient has a one-vessel runoff in the lower extremity. Preservation of the distal blood supply is critical and that is the main advantage of an end-to-side anastomosis.
In general, an end-to-side anastomosis is more technically difficult with longer ischemia time. Kinking of the vessels is still possible with end-to-side anastomosis and therefore is not a major advantage to this technique. There is no added benefit in visualizing the vessel and it is generally more difficult to see the entire vessel compared to an end-to-end anastomosis. This technique does not preferentially allow for an anastomosis in the zone of injury.
Finally, it is controversial whether or not the flap survival rate is different between end-to-side and end-to-end anastomosis. An early paper by Godina shows an advantage for end-to-side; however, many subsequent papers have contradicted these results.
A 34-year-old man is scheduled to undergo soft-tissue coverage with an anterolateral thigh free flap to treat a nonhealing, complex, traumatic wound involving the distal third of the left lower extremity. Which of the following is most likely to have the greatest effect on anastomotic patency?
A ) Anastomotic type
B ) Anticoagulation
C ) Magnification equipment
D ) Surgical skill
E ) Suture technique
The correct response is Option D.
Acland outlined five basic factors that influence anastomotic patency: (1) surgical precision, (2) size of the vessel, (3) blood flow, (4) tension, and (5) use of anticoagulation and antithrombotic medication.
Studies have not demonstrated the efficacy of anticoagulation in improving microvascular patency rates and free flap survival. Studies evaluating types of anastomosis, including end-to-end and end-to-side, and those comparing suture techniques, including interrupted or running sutures, have also not demonstrated significant differences in patency rate. Both loupe magnification and an operating microscope can be successfully utilized in microsurgery.
The skill and experience of the surgeon in using an atraumatic technique for the dissection and anastomosis of the vessels, assuring good vessel apposition, and avoiding tension, compression, or kinks in the vascular pedicle, remain the most critical factors in microsurgery.
When harvesting the profunda artery perforator flap for breast reconstruction, which of the following structures does the perforating vessel travel through in the majority of patients?
A) Adductor longus muscle
B) Adductor magnus muscle
C) Gracilis muscle
D) Septum between the adductor longus and sartorius muscles
E) Septum between the adductor magnus and semimembranosus muscles
The correct response is Option B.
Proximal thigh profunda artery perforators most commonly course through the adductor magnus muscle not the adductor longus muscle. In these cases where musculocutaneous proximal perforators are used, fibers of the adductor magnus muscle will be divided for PAP flap harvest.
The profunda artery perforator (PAP) flap is a fasciocutaneous flap frequently employed for breast reconstruction as an alternative to the deep inferior epigastric artery perforator flap. The PAP flap has also been described for lower extremity resurfacing and burn scar contracture release, as well as pedicled for perineal reconstruction. The PAP flap skin paddle is harvested as either a transverse skin paddle beneath the gluteal and groin crease or with a vertical skin paddle harvested in the frog leg position. The most common donor site skin paddle orientation for breast reconstruction is a transverse ellipse of skin inferior to the gluteal crease to camouflage the donor site scar.
The profunda artery perforators emerge from the profunda vessels longitudinally down the postero-medial aspect of the thigh. Most patients have a proximal perforator that supplies the transverse ellipse of skin and adipose tissue most commonly employed for breast reconstruction. However, enough variability exists in perforator location, that preoperative CT angiography is recommended to confirm the presence of a proximal perforator.
The PAP flap perforating vessel may travel in a septocutaneous plane between the gracilis and adductor magnus at the level of the deep investing fascia and between the adductor longus and magnus closer to its origin but not between the muscles listed as alternate septocutaneous choices. The transverse upper gracilis (TUG) flap perforator travels through the gracilis muscle before perfusing the medial thigh skin.
A 20-year-old man undergoes harvest of the lower extremity free flap as shown in the photographs. A long length of bone is required for the reconstruction. With proximal dissection and osteotomy, which of the following nerves is at the highest risk for injury?
A) Common peroneal
B) Lateral femoral cutaneous
C) Saphenous
D) Sural
E) Tibial
The correct response is Option A.
The fibula is a long, thin triangular bone of the lower extremity. The fibula can be harvested as a free osseous or free osteoseptocutaneous flap with primary blood supply from the peroneal artery. Preservation of 4 to 6 cm of length proximally and 6 cm distally is important for the maintenance of stability of the knee and ankle. The peroneal nerve should be identified prior to proximal dissection as it wraps around the fibular neck. At this level, the nerve can be palpated and marked out to avoid injury during proximal dissection.
The common peroneal nerve arises from the sciatic nerve, running along the biceps femoris toward the posterior fibular head. It wraps around the proximal fibula at the neck, continuing laterally through a fibrous tunnel comprised of the aponeurosis of the peroneus longus, lateral gastrocnemius, and soleus muscles. Under the peroneus longus, the nerve branches into the superficial and deep branches; the superficial branch runs under the peroneus longus to innervate the peroneus longus and peroneus brevis, and it provides cutaneous sensation for the foot dorsum. The superficial peroneal nerve can be injured during anterior dissection for the skin paddle at the mid lower leg.
The deep peroneal nerve can be identified after deep dissection through the interosseus membrane into the anterior lower leg compartment. This nerve can be found between the extensor hallucis longus and extensor digitorum longus muscles. The deep peroneal nerve provides innervation to the muscles of the anterior compartment and sensation to the first web space.
The tibial nerve branches from the sciatic nerve, running through the popliteal fossa, sitting lateral to the neurovascular bundle, then proceeds deep to the gastrocnemius and soleus muscles. It then proceeds to run along the medial ankle posterior to the medial malleolus and provides sensory innervation to the plantar foot. Along its path, it provides innervation to the posterior compartments and intrinsic muscles.
The sural nerve is a sensory nerve, traditionally a confluence of the medial sural nerve from the tibial nerve and a lateral sural cutaneous nerve from the common peroneal nerve. The nerve is found superficial to the superficial posterior compartment in the posterior calf at the midline, lateral to the Achilles tendon; then it veers laterally in the ankle. This nerve provides sensation to the dorsolateral foot.
The saphenous nerve is the terminal sensory nerve of the femoral nerve; it perforates the femoral canal and becomes superficial and descends with the saphenous vein. It descends along the medial lower leg from the medial epicondyle region to the medial malleolus. Sensation is provided for the anteromedial lower leg. This nerve is unlikely to be injured in free fibula harvest given its medial leg location.
The lateral femoral cutaneous nerve arises from the posterior divisions of the L2 and L3 spinal nerves. The nerve usually exits from the lateral psoas muscle, heading towards the anterior superior iliac spine. It exits below the inguinal ligament and bifurcates. The sensory distribution is the skin of the anterolateral and lateral thigh. Given the proximal location, this nerve should not be in the region of dissection.
A 43-year-old woman is evaluated 6 hours after undergoing delayed breast reconstruction with deep inferior epigastric artery perforator flaps. On Doppler examination, arterial signals are present. Capillary refill time is 3 seconds on the right and 1 second on the left. A photograph is shown. Which of the following is the most appropriate management of the left breast?
A) Administration of systemic heparin
B) Administration of systemic tissue plasminogen activator
C) Application of leeches
D) Return to the operating room
E) Observation
The correct response is Option D.
The most appropriate management is exploration of the left flap to assess anastomotic patency and pedicle orientation. This flap is hyperemic with brisk capillary refill and present arterial signals. These are all signs of venous insufficiency, and emergent exploration is indicated to assess the vascular pedicle for kinking or thrombosis. Application of leeches will drain excess blood from the flap but will not address the underlying problem. Observation is unacceptable because there are signs of venous insufficiency, and this requires urgent intervention. Systemic heparin will prevent further clot formation but will not dissolve an acute clot or resolve pedicle kinking. Systemic tissue plasminogen activator would greatly increase this patient’s risk of bleeding. This agent should only be used within a flap.
