Page 92 - Read Online

Page 4 of 13 Myers et al. Plast Aesthet Res 2023;10:38 https://dx.doi.org/10.20517/2347-9264.2022.150

include antiphospholipid syndrome (anticardiolipin, lupus anticoagulant), and some forms of
hyperhomocysteinemia. Hypercoagulable states pose a challenge in autologous free flap reconstruction
because they are frequently undetected preoperatively and are often only brought on by a precipitating
event, such as a microvascular procedure [25,27] .

Free flap thrombosis more commonly occurs in the postoperative period than intraoperatively in patients
[22]
with known hypercoagulability disorders . Multiple studies have also demonstrated that flap salvage rates
are significantly higher if flap thrombosis and re-exploration occur early in the postoperative period [28-31] .
Wang et al. found that the failure rate approaches 100% when flap thrombosis occurs on postoperative days
4 and 5 in hypercoagulable patients . For these reasons, it is imperative to screen patients for
[28]
hypercoagulable disorders preoperatively to minimize the risk of postoperative flap thromboses that are
difficult to salvage. Perioperative risk assessment can significantly reduce the occurrence of flap
thrombosis . During the initial preoperative consultation, it is important to obtain a thorough history by
[32]
asking questions regarding (1) personal history of blood clots, including deep vein thrombosis or
pulmonary embolism; (2) personal history of miscarriages; (3) personal history of strokes at a young age;
and (4) family history of clotting or previously diagnosed coagulation disorders [28,32] . If hypercoagulability is
suspected based on history, referral to hematology for further workup is warranted. Patients who were
referred to a hematologist have shown a higher flap success rate compared to patients who did not, as
administration of an appropriate perioperative anticoagulation regimen can mitigate risk . For instance,
[28]
Kalmar et al. discovered that a platelet count of > 250 K/mcL (P = 0.004) is associated with a higher rate of
flap failure . The authors suggest there may be a role for personalized anticoagulation protocols for
[33]
thrombocytosis with agents specifically targeting platelets, such as aspirin, ticlodipine, and dipyramidole .
[33]
Genetic testing should also be considered, especially in patients with a family history of clotting episodes. It
is recommended that a formal hypercoagulable workup be performed at a minimum of 4-6 weeks after a
traumatic event such as surgery, as coagulation factors remain elevated during this time, specifically
thrombin, that will alter the results of the testing [13,34] . After a patient is confirmed to have a hypercoagulable
disorder, surgeons can collaborate with hematologists to determine a perioperative anticoagulation regimen,
especially if salvage free-tissue transfer is to be attempted. Literature is sparse on success and failure rates for
breast reconstruction of an attempted second flap after an initial failure in a patient with a known
hypercoagulable condition. In a series described by Hamdi et al., two patients with hypercoagulable
conditions underwent a second free flap with a successful free tissue transfer with appropriate
[17]
anticoagulation .

ANTICOAGULATION REGIMEN
In patients without hypercoagulable disorders, prophylactic antithrombotic therapy is used to minimize the
risk of venous thromboembolic events but can also decrease the incidence of microvascular thrombosis
after free flap surgery . There is no consensus on anticoagulation protocols and relevant studies are
[25]
generally lacking. For example, at the authors’ institution, it is typical to administer subcutaneous heparin
5,000 units preoperatively, aspirin 300 mg rectal suppository at the end of the case, followed by Lovenox 40
mg QD starting postoperative day 0 and aspirin 325 mg starting on the first postoperative for 30 days for
patients without increased risk of thrombosis. Liu et al. reported a regimen of intraoperative heparin bolus
of 2,000 units intravenously followed by five days of heparin infusion at 500 unit/hour in patients who are at
risk of hypercoagulability . Wang et al. presented four different anticoagulation protocols based on
[35]
[28]
surgeon preference at a single institution . It is apparent that prophylactic antithrombotic regimen has
varied through the decades amongst different institutions and surgeons.