Heparin-induced thrombocytopenia and thrombosis as an under-diagnosed cause of flap failure in heparin-naive patients: A case report and systematic review of the literature

Heparin-induced thrombocytopenia in lower extremity free tissue transfers

BACKGROUND

Heparin-induced thrombocytopenia (HIT) an immunologically mediated reaction to heparin products, can lead to severe thrombocytopenia and potentially life-threatening thrombotic events. In microsurgery, a missed or delayed diagnosis of HIT can cause complications requiring revision operations, flap loss, or limb loss. Surgeons must remain vigilant for this uncommon yet potentially devastating condition and keep abreast of management strategies.

METHODS

CPT and ICD-10 codes in electronic medical records were used to collect demographic information, clinical courses, and outcomes for patients with a HIT diagnosis who underwent lower extremity free tissue transfer in one institution.

RESULTS

The authors' institution performed 415 lower extremity free flaps in 411 patients during the 10-year study period. Flap salvage rate was 71% for compromised lower extremity flaps without HIT, and 25% in those with HIT. Four patients (four flaps) met study inclusion criteria during the study period. Three of the four flaps failed and were later debrided; one was rescued after a takeback for anastomosis revision. Two patients successfully underwent a delayed second free flap procedure after recovery, and one was salvaged with a pedicled muscle flap.

CONCLUSIONS

Surgeons should monitor for HIT by establishing coagulation panel and platelet count baselines and trending these values in the early post-operative period for patients treated with heparin products. The 4T score can be used to screen for HIT with high clinical suspicion. Arterial thrombosis or poor flap perfusion despite sound microvascular technique could suggest HIT. Surgical and medical management including strict heparin avoidance can prevent adverse events for these patients.

Leech Therapy Protects Free Flaps against Venous Congestion, Thrombus Formation, and Ischemia/Reperfusion Injury: Benefits, Complications, and Contradictions

The use of free cutaneous or myocutaneous flaps in some surgeries, especially in reconstructive surgeries, is routine and imperative; nevertheless, it is controversial because of fear of flap loss due to tissue congestion and partial or complete necrosis. Different mechanisms are discussed in this process, and based on the involved mechanisms, various agents and approaches are suggested for flap salvage. Among these agents and strategies, leech therapy (hirudotherapy) can be a valuable complementary treatment; however, in this way, full attention should be given to all beneficial and harmful aspects to reach the best results. This study included a literature review of the essential complications following free tissue transfer and explained the effects of leech therapy for the respective complications. Based on the review of the literature, the essential complications following free tissue transfer were (I) venous obstruction and congestion, (II) delay in blood flow reestablishment, (III) ischemia/reperfusion injuries, and (IV) thrombus formation. Leech therapy can protect free flaps against the mentioned complications as a complementary treatment. Leech therapy is an appropriate complement, however, not a definite approach for flap salvage. Therefore, in some patients, other alternative methods or even flap removal may be a better option.

Heparin-induced thrombocytopenia and thrombosis in primary lymphedema patients who underwent vascularized lymph node transplantations

BACKGROUND

Heparin-induced thrombocytopenia and thrombosis (HITT) may result in microsurgical flap failure. This study investigated the outcomes of HITT in primary lymphedema patients who underwent vascularized lymph node transplantations (VLNT).

METHODS

Between 2012 and 2019, primary lymphedema patients who underwent VLNTs were retrospectively included. The 4Ts score was used to categorize patients into HITT (scores of 5-7) and non-HITT (score < 5) groups. Outcome evaluations included the re-exploration rate, success rate, circumferential differences, cellulitis episodes, and Lymphedema Specific Quality of Life Questionnaire (LYMQoL) scores.

RESULTS

Twenty-six and 15 patients with 31 and 16 VLNTs were included in the HITT and non-HITT groups, respectively. The HITT group had significantly greater first, second and third re-exploration rates of 38.7% (12/31), 25.7% (8/31), and 6.5% (2/31) than the non-HITT group (6.3%, 0%, and 0%, all p < 0.01), respectively. The platelet counts significantly decreased by 21.0% in the HITT group compared with the non-HITT group (14%) on postoperative Day one (p < 0.01) with a cutoff value of 17% and AUC = 0.88.

CONCLUSIONS

HITT may cause a high re-exploration rate of VLNTs in primary lymphedema patients. The 17% reduction in platelets on postoperative day one was an early sign for detecting HITT.

Low-molecular-weight heparin-associated multiple digital necrosis in a patient as a result of heparin-induced thrombocytopenia syndrome

Heparin-induced thrombocytopenia syndrome (HITS) is a rare complication of low-molecular-weight heparin (LMWH). It is an autoimmune-mediated side effect of LMWH which is caused by platelet-activating antibodies that recognize platelet factor-4/ heparin complexes. Although HITS often leads to thrombosis in large veins and arteries, it can be presented as microvascular thrombosis. In this article, we report a case of HITS complicated with multiple digital necrosis after administration of LMWH.

Early Suspicion of Heparin-Induced Thrombocytopenia for Successful Free Flap Salvage: Reports of Two Cases

Heparin-induced thrombocytopenia (HIT) is an underestimated complication of heparin treatment. Flap loss and related morbidity (even mortality) are caused by occlusion of the capillary vessels by a highly immunogenic complex formed by adherence of antiheparin antibodies to platelet factor 4. Early suspicion and effective treatment of HIT developing in two free flaps are described. We report on the management of two patients with HIT. Both patients were treated successfully by early suspicion and hematology consultation. Heparin products were discontinued; the patients were switched to a nonheparin anticoagulant. We emphasize the importance of early diagnosis, hematologist assessment, and a change to a nonheparin anticoagulant to prevent flap failure and possibly the catastrophic consequences of such failure.

Heparin-induced thrombocytopenia (HIT): Review of incidence, diagnosis, and management

Heparin-induced thrombocytopenia (HIT) is a life and limb-threatening complication of heparin exposure. Here, we review the pathogenesis, incidence, diagnosis, and management of HIT. The first step in thwarting devastating complications from this entity is to maintain a high index of clinical suspicion, followed by an accurate clinical scoring assessment using the 4Ts. Next, appropriate stepwise laboratory testing must be undertaken in order to rule out HIT or establish the diagnosis. In the interim, all heparin must be stopped immediately, and the patient administered alternative anticoagulation. Here we review alternative anticoagulation choice, therapy alternatives in the difficult-to-manage patient with HIT, and the problem of overdiagnosis.

Incidence of heparin-induced thrombocytopenia in lower-extremity free flap reconstruction correlates with the overall surgical population

BACKGROUND

Lower-extremity free flap reconstruction is a growing trend in the management of lower extremity wounds. Heparin-induced thrombocytopenia (HIT) is a significant risk to free flap reconstruction. The purpose of this study was to investigate the incidence of HIT in patients receiving lower-extremity free flap surgery.

METHODS

We conducted a retrospective, single center, IRB approved cohort study in which we reviewed all patients who received lower-extremity free flap surgeries between 2011 and 2016. The 4T and HIT Expert Probability (HEP) scores were calculated to assess the likelihood of HIT.

RESULTS

One hundred patient charts revealed three patients with HIT. One patient was excluded due to a prior diagnosis of HIT. HIT incidence in patients receiving lower-extremity free flaps was between 1% and 3%, which is consistent with the national average. 4T scores indicated that two of three HIT-positive patients had a high probability of HIT (approximately 64%), and one of three HIT-positive patients had an intermediate probability (approximately 14%). HEP scoring indicated that all the three (100%) patients had HIT.

CONCLUSIONS

These data suggest that the incidence of HIT in patients receiving lower-extremity free flaps correlates with the incidence of HIT nationally. The use of available scoring methods and other algorithms, combined with patient history helps to assess the immediate perioperative risks of HIT in the absence of rapid immunologic confirmatory tests. This knowledge can allow for successful free flap salvage or for performance of free flaps in patients with a history of HIT.

Free flap loss caused by heparin-induced thrombocytopenia and thrombosis (HITT): a case report and literature review

Heparin-induced thrombocytopenia and thrombosis (HITT) represents a dramatic condition that is difficult to diagnose because of nuanced clinical presentation. Therefore, in every case of microvascular thrombosis during heparin-therapy prompt suspicion about HITT is necessary to avoid flap necrosis. We present a case of HITT which, as the 8 other articles reviewed, clearly shows that HITT is difficult to diagnose and complex to manage. Microvascular reconstruction is the first choice in head and neck reconstruction; unfortunately, dramatic outcomes in free flap surgery due to unpredictable thrombotic events are still reported in the English literature. More knowledge is required about HITT and reaching a consensus about thrombotic prevention in microsurgery could be helpful. Furthermore, a careful anamnesis can help minimise unexpected situations.

Exposed tibial bone after burns: Flap reconstruction versus dermal substitute

A 44 years old male patient had suffered extensive 3rd degree burns on both legs, undergoing thorough surgical debridement, resulting in both tibias being exposed. Approximately 5 months after the incident he was referred to the Department of Plastic and Reconstructive Surgery of the University Hospital Gent, Belgium, to undergo flap reconstruction. Free flap surgery was performed twice on both lower legs but failed on all four occasions. In between flap surgery, a dermal substitute (Integra(®)) was applied, attempting to cover the exposed tibias with a layer of soft tissue, but also without success. In order to promote the development of granulation tissue over the exposed bone, small holes were drilled in both tibias with removal of the outer layer of the anterior cortex causing the bone to bleed and subsequently negative pressure wound therapy (NPWT) was applied. The limited granulation tissue resulting from this procedure was then covered with a dermal substitute (Glyaderm(®)), consisting of acellular human dermis with an average thickness of 0.25mm. This dermal substitute was combined with a NPWT-dressing, and then served as an extracellular matrix (ECM), guiding the distribution of granulation tissue over the remaining areas of exposed tibial bone. Four days after initial application of Glyaderm(®) combined with NPWT both tibias were almost completely covered with a thin coating of soft tissue. In order to increase the thickness of this soft tissue cover two additional layers of Glyaderm(®) were applied at intervals of approximately 1 week. One week after the last Glyaderm(®) application both wounds were autografted. The combination of an acellular dermal substitute (Glyaderm(®)) with negative pressure wound therapy and skin grafting proved to be an efficient technique to cover a wider area of exposed tibial bone in a patient who was not a candidate for free flap surgery. An overview is also provided of newer and simpler techniques for coverage of exposed bone that could question the universal plastic surgery paradigm that flap surgery is the only way to cover these defects.