Microsurgery 03-22, 24 Flashcards
An otherwise-healthy 50-year-old man undergoes resection and immediate reconstruction with an anterolateral thigh free flap for recurrent squamous cell carcinoma of the oral cavity. Medical history includes resection, primary closure, and radiation. Intraoperatively, the patient is receiving low-dose phenylephrine infusion for blood pressure maintenance. Which of the following strategies is most likely to decrease the risk for pedicle thrombosis in this patient?
A) Administration of intravenous fluid boluses to wean off phenylephrine
B) Anastomosis to nonradiated recipient neck vessels
C) End-to-end anastomosis instead of end-to-side anastomosis
D) Intravenous heparin bolus 10 minutes before pedicle ligation
E) Venous anastomosis to internal jugular vein instead of the external jugular vein
The correct response is Option B.
Anastomoses performed in radiated fields have higher rates of flap loss as compared with nonradiated recipient neck vessels in head and neck reconstruction. Systemic heparin has not been shown to decrease pedicle thrombosis. However, vessel irrigation with topical heparin has been shown to decrease thrombosis at the anastomosis site in animal models, and therefore, most microsurgeons perform this practice. Vasopressors do not increase the risk for pedicle thrombosis. A recent meta-analysis showed a decreased rate of pedicle thrombosis with perioperative vasopressor administration in head and neck reconstruction, likely due to improved hemodynamics and decreased detrimental effects of fluid overload. There is no difference in pedicle thrombosis rate between end-to-end and end-to-side arterial or venous anastomosis, as shown in a recent meta-analysis. There is no proven difference in vessel patency rates between the internal jugular and external jugular systems.
During surgical exploration for a failing free flap, a surgeon revises the anastomosis, performs mechanical thrombectomy with a Fogarty catheter, and injects the flap with tissue plasminogen activator (tPA). Which of the following is the mechanism of action of tPA in fibrinolysis to increase flap survival and decrease fat necrosis?
A) Activates plasmin binding to fibrin
B) Converts plasminogen to plasmin
C) Forms a complex with plasminogen
D) Inhibits plasminogen activator inhibitor type-1
The correct response is Option B.
Tissue plasminogen activator (tPA) is a protease that cleaves a peptide bond in plasminogen, converting it to plasmin. tPA and urokinase have similar mechanisms in converting plasminogen to plasmin through cleavage. Plasmin is an enzyme that lyses the cross-linking between fibrin molecules and therefore breaks up clot formation. Streptokinase, which is derived from Streptococcus and is no longer commercially available in the United States, forms a complex with plasminogen, which then converts to plasmin. Plasminogen activator inhibitor type-1 (PAI-1) binds to tPA and inactivates it by forming a complex. An inhibitor of PAI-1 would facilitate the pathway of fibrinolysis, but tPA does not act in this manner.
A 64-year-old man presents with biopsy-proven squamous cell carcinoma of the tongue. Excision and reconstruction are planned. Allen tests on both sides show complete radial dominance, which is confirmed with non-invasive ultrasound. The plan is to proceed with an ulnar artery perforator flap from the non-dominant hand. When comparing the ulnar artery perforator flap to the radial forearm flap, which of the following is a major benefit of the ulnar artery flap?
A) It has a larger pedicle artery diameter
B) It has a longer pedicle length
C) It has a lower flap thrombosis rate
D) It is a better choice to incorporate bone as an osteocutaneous flap
E) It is less likely to result in tendon exposure at the donor site
The correct response is Option E.
On the basis of the more proximal location of the flap, the donor site is able to be closed primarily more commonly than a radial forearm flap. When it is not closed primarily, typically the exposed deeper structures are muscle bellies rather than peritenon or tendon in the more distally located and radially positioned radial forearm flap.
The other options are incorrect. The radial forearm flap has a longer pedicle. The ability to incorporate bone into the flap is better reported in an osteocutaneous radial forearm. The flap thrombosis rates have been shown to be equivalent and the arterial diameter is similar or larger in the radial artery depending on the publication. Another benefit of the ulnar artery perforator flap is that the ulnar side of the arm is less hair-bearing and therefore may serve as better choice for intraoral reconstruction.
A 65-year-old woman undergoes breast reconstruction with a free superficial inferior epigastric artery (SIEA) flap. The vascular pedicle is 1.5 mm diameter, including both the artery and vein. The second/third intercostal perforators on the left chest are prepared as the recipient vessels. The surgeon performs a hand-sewn microvascular arterial anastomosis with 9-0 suture and a 1.5-mm anastomotic coupler for the vein. This patient is at increased risk for which of the following?
A) Arterial occlusion
B) Interposition vein graft
C) Kinking of the vascular pedicle
D) Vasospasm
E) Venous thrombosis
The correct response is Option E.
This patient has a high risk for venous thrombosis given that the 1.5-mm anastomotic coupler was used. In a large retrospective study, Hansen et al, found that based on 5643 reconstructions, the 1.5-mm diameter coupler had an overall thrombosis rate of 6.9%. This is significantly higher than all other coupler sizes. In another study, Jandali et al, found that using the anastomotic coupler in breast reconstruction is safe. In fact, these authors demonstrated a 0.6% flap loss rate in 1000 cases of autologous breast reconstruction. When encountered with a recipient vein that is less than 2.0 mm, the surgeon should either perform a hand-sewn anastomosis or find different recipient vessels.
A 58-year-old man requires free tissue transfer for soft-tissue reconstruction of a head and neck defect. Which of the following surgical interventions is most likely to improve flap survival?
A) End-to-end anastomosis
B) Multiple perforators
C) Muscle flap only
D) Supercharging
E) Venous coupler
The correct response is Option E.
In a recent study of 2296 head and neck free tissue transfers, Chang et al demonstrated that the use of a venous coupler had a significantly decreased complication rate compared with performing a hand-sewn anastomosis. Further analysis yielded no significance in survival rates with supercharging, use of multiple perforators, or orientation of anastomosis. They noted an increased risk for failure with muscle-only flaps compared with fasciocutaneous or osteocutaneous flaps. Other authors have demonstrated the benefits of venous couplers in head and neck free tissue reconstruction as well.
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 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 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.
When compared with liberal fluid administration for pressure support, vasopressors have which of the following effects on the overall success of deep inferior epigastric artery perforator (DIEP) flap breast reconstruction?
A) Delay in postoperative patient mobilization
B) Increase in the risk of total or partial flap loss
C) Increase in the risk of venous congestion
D) No difference in the rate of pedicle thrombosis
The correct response is Option D.
Traditionally, the use of vasopressors in free flap surgery has been avoided due to the presumed risk of pedicle vasospasm leading to flap failure. However, recent studies have indicated that this assumption may not be accurate. Additionally, the fear of vasopressor-associated flap complications has led to the practice of liberal fluid administration, which has failed to demonstrate any benefits when compared with a fluid-restrictive vasopressor strategy. Multiple prospective interventional trials and meta-analyses have reported that the use of vasopressors results in no detectable negative impact on flap survival or overall patient outcome. Specifically, intraoperative use of phenylephrine, ephedrine, or calcium chloride as an intravenous bolus does not increase in the risk of total or partial flap loss, delay postoperative patient mobilization or increase the risk of venous congestion. The use of vasopressors in free flap surgery is not contraindicated.
A 59-year-old right-hand–dominant woman with type 2 diabetes and coronary artery disease undergoes a radial forearm adipofascial perforator flap for palmar contracture release and resurfacing to treat a severely contracted burn scar. Which of the following characteristics is a benefit of this flap choice?
A) It can be designed as a myofascial flap
B) It has a distal pivot point at the radial styloid
C) It has robust, 1.5- to 2-mm perforators
D) It is a reliably thin, pliable flap
E) It is a sensate flap
The correct response is Option D.
The radial forearm adipofascial perforator flap is a reliably thin, pliable flap. As such, the flap is a good option for reconstruction of the distal upper extremity when a thin flap is desired, such as for palmar/dorsal hand coverage, revision carpal tunnel/median nerve surgery, and radioulnar synostosis surgery. Other advantages of this flap include avoiding the need to sacrifice the radial artery, shorter operative time compared with free tissue transfer, and low donor morbidity. The vascular supply to the flap is a series of roughly 10 small 0.3- to 0.9-mm septocutaneous radial artery perforators found in the septum between the flexor carpi radialis and the brachioradialis tendons. The most distal perforator arises approximately 1.5 cm proximal to the radial styloid. Therefore, the pivot point for this flap is safely 4 cm proximal to the radial styloid. Since the flap is supplied by the adipofascial perforating vessels superficial to the radial artery, the inclusion of muscle in the flap design is not reliable. During flap elevation, the superficial radial nerve and lateral antebrachial cutaneous nerves are identified and preserved, but are not included into the flap.
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 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 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 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 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 healthy 55-year-old woman underwent bilateral breast reconstruction with free deep inferior epigastric perforator (DIEP) flaps. Tissue oximetry-based flap monitoring is used. Which of the following is the main advantage of this technique over a hand-held Doppler with clinical assessment?
A) Direct blood flow measurement
B) Ease of use
C) Improved flap salvage rate
D) Less expensive modality
E) Operator must be bedside
The correct response is Option C.
The main advantage of using tissue oximetry-based monitoring is that it improves flap salvage rates. Tissue oximetry, or near-infrared spectroscopy, is increasing in popularity among microsurgeons and has been shown to be the third most commonly used technique after clinical examination and hand-held Doppler. Rather than directly monitoring flow, tissue oximetry uses infrared light to measure the relative concentrations of oxygenated and deoxygenated hemoglobin. By measuring oxygenation rather than flow, the probe is relatively unaffected by movement artifacts. Recent studies emphasize its value in identifying flap compromise before clinical signs of arterial or venous thrombosis. In a 2011 study, Lin et al. reported an increased flap salvage rate at their institution with the use of near-infrared spectroscopy, from 57.7 to 93.8% (p = 0.015), despite no significant increase in their rate of reexploration, attributing this improvement to earlier recognition of vascular compromise. In a recent small prospective cohort study, Lohman et al. followed 38 free flaps with physical examination and five technologies, including handheld Doppler, implantable Doppler, and tissue oximetry. Although primarily a descriptive study, they concluded that tissue oximetry was the first technology to record signs of flap compromise.
Though tissue oximetry-based flap monitoring is easy to use, so is a hand-held Doppler, so that is not the main advantage. It does have a higher financial investment to buy the system, but over time it could be argued it more than pays for itself given the improved flap salvage rates. Unlike the hand-held Doppler, this modality has a continuous read on the monitor, the examiner need not be in the presence of the patient, and, in fact, can visualize the readings on a smart phone through an app.
A 69-year-old woman with breast cancer undergoes bilateral breast reconstruction using free deep inferior epigastric perforator (DIEP) flaps. During surgery, she has onset of hypotension that is unresponsive to standard crystalloid and colloid solutions. The anesthesia team elects to administer norepinephrine to correct her blood pressure. Which of the following flap-related outcomes is most likely?
A) Flap loss
B) Hematoma
C) Reoperation
D) Wound dehiscence
E) No effect
The correct response is Option E.
There are no known increased flap complications with use of vasopressive medications. In fact, one study has shown decreased intraoperative flap complications compared with controls with the use of ephedrine. Traditional dogma is that vasopressors should be avoided during free tissue transfer due to concern that vasoconstriction or thrombosis could occur, resulting in compromised flap perfusion and subsequent flap loss. Most authors argue for standard intravenous fluid replacement or adjustment of anesthetic medications when feasible to first address the hypotension. However, numerous articles have suggested the safety of vasopressive medications in the setting of free tissue transfer. In fact, there are studies correlating excess intravenous fluid administration with increasing complication rates in free transverse rectus abdominis musculocutaneous (TRAM) flaps. As such, vasopressive medications should be considered when standard anti-hypotensive remedies have failed.
The original concern about vasoconstriction of the flap vessels with systemic vasopressor administration and resultant decreased perfusion or thrombosis has largely been disproven. This occurs likely because of sympathetic denervation due to flap transfer, sympathectomy with adventitial removal, and topical use of vasodilators, such as papaverine or nicardipine. Additionally, any vasoconstrictive effect on the flap vessels is more than overcome by increased flap perfusion caused by an elevated blood pressure.
A 45-year-old male fitness instructor has squamous cell carcinoma of the oral cavity requiring reconstruction with a soft-tissue free flap. The patient is very concerned about maintaining all muscular function at the flap donor site. To address the patient’s concern, which of the following fasciocutaneous flaps should be used for reconstruction to minimize muscular donor site morbidity?
A) Anterolateral thigh flap
B) Deep inferior epigastric artery perforator flap
C) Medial sural artery perforator flap
D) Parascapular flap
E) Profunda artery perforator flap
The correct response is Option D.
The benefit of perforator flaps over traditional musculocutaneous flaps is the ability to preserve muscle at the donor site. Depending on perforator anatomy, it can either traverse between surrounding myofascial units requiring no muscle sacrifice, or alternatively pass through the muscle substance requiring division of a small amount of muscle to liberate the flap. The anterolateral thigh (ALT) or deep inferior epigastric artery perforator (DIEP) flaps have variable perforator anatomy containing either septal or muscular perforators, or both within the same flap. The profunda and medial sural artery perforator flaps have vessels that pierce the adductor magnus and gastrocnemius muscles, respectively. Of the options listed, only the parascapular flap consistently has a septal perforator located between the teres major, teres minor, and the triceps.
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 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.
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.
