Homocystinuria: An Unrecognized Cause of Microvascular Failure

Microsurgical breast reconstruction and primary hypercoagulable disorders

BACKGROUND

Primary hypercoagulable disorders pose a significant challenge to microsurgeons and have traditionally been regarded as a relative contraindication to free tissue transfer. Since free flaps offer numerous advantages in breast reconstruction, there is an effort to expand the population to whom these operations can be safely offered. The purpose of this study is to describe our chemoprophylaxis regimen in cases of primary hypercoagulability, as well as to compare flap outcomes and complications between women with and without hypercoagulability.

PATIENTS AND METHODS

A single institution retrospective review identified 15 patients (25 flaps) with known primary hypercoagulability who underwent microsurgical breast reconstruction from 2010 through 2020. There were 785 patients (1268 flaps) without primary hypercoagulability who underwent microsurgical breast reconstruction, including 40 patients (73 flaps) with a history of venous thromboembolism (VTE), evaluated for comparison. Patient characteristics, thromboprophylaxis regimen, and surgical outcomes were collected. In carrying out this cohort study, we have adhered to Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

RESULTS

Fifteen patients with primary hypercoagulability were identified, including heterozygous factor V Leiden mutation (n = 12), protein S deficiency (n = 1), prothrombin mutation (n = 1), and primary antiphospholipid syndrome (n = 1). Thirteen of these (87%) were discharged with an extended LMWH course. There was no postoperative VTE or mortality in this cohort, and no significant difference in hematoma or transfusion compared with the control group (p = .31, p = .87, respectively). The flap loss rate was 4% in the hypercoagulable group compared with 0.92% in the control group (p = .15). The salvage for arterial or venous compromise in the hypercoagulable group was poor (0% vs. 52%, p = .3).

CONCLUSION

Microsurgical breast reconstruction in women with primary hypercoagulability disorders is feasible with acceptable risk of flap loss but poor salvage potential. Postoperative thromboprophylaxis with extended prophylactic LMWH in this population appears to be a safe regimen.

Risk-Stratified Anticoagulation Protocol Increases Success of Lower Extremity Free Tissue Transfer in the Setting of Thrombophilia

BACKGROUND

Optimal perioperative thromboprophylaxis is crucial to avoid flap thrombosis and achieve high rates of microsurgical success. At the authors' institution, implementation of a risk-stratified anticoagulation (AC) protocol preliminarily showed a reduction in postoperative thrombotic events and flap loss. The authors present an updated analysis of surgical outcomes using risk-stratified AC in thrombophilic patients who underwent free tissue transfer (FTT) reconstruction for nontraumatic lower extremity (LE) wounds.

METHODS

The authors retrospectively reviewed patients who underwent FTT to an LE from 2012 to 2021. Their risk-stratification AC protocol was implemented in July of 2015. Low-risk and moderate-risk patients received subcutaneous heparin. High-risk patients received heparin infusion titrated to a goal partial thromboplastin time of 50 to 70 seconds. Before July of 2015, nonstratified patients were treated with either subcutaneous heparin or low-dose heparin infusion (500 U/hour). Patients were divided into two cohorts (nonstratified and risk-stratified) based on date of FTT reconstruction. Primary outcomes included rates of postoperative complications, flap salvage, and flap success.

RESULTS

Two hundred nineteen hypercoagulable patients who underwent FTT to an LE were treated with nonstratified ( n = 26) or risk-stratified ( n = 193) thromboprophylaxis. The overall flap success rate was 96.8% ( n = 212). Flap loss was lower among risk-stratified patients (1.6% versus 15.4%; P = 0.004), which paralleled a significant reduction in postoperative thrombotic events (2.6% versus 15.4%; P = 0.013). Flap salvage was accomplished more often in the risk-stratified cohort (80% versus 0%; P = 0.048). Intraoperative anastomotic revision (OR, 6.10; P = 0.035) and nonrisk stratification (OR, 9.50; P = 0.006) were independently associated with flap failure.

CONCLUSIONS

Hypercoagulability can significantly affect microsurgical outcomes. Implementation of a risk-stratified AC protocol can significantly improve flap outcomes.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Preoperative Platelet Count Predicts Lower Extremity Free Flap Thrombosis: A Multi-Institutional Experience

BACKGROUND

Thrombocytosis in patients undergoing lower extremity free tissue transfer may be associated with increased risk of microvascular complications. This study assessed whether preoperative platelet counts predict lower extremity free flap thrombosis.

METHODS

All patients undergoing lower extremity free tissue transfer at Duke University from 1997 to 2013 and at the University of Pennsylvania from 2002 to 2013 were retrospectively identified. Logistic regression was used to assess whether preoperative platelet counts independently predict flap thrombosis, controlling for baseline and operative factors.

RESULTS

A total of 565 patients underwent lower extremity free tissue transfer, with an overall flap thrombosis rate of 16 percent (n = 91). Elevated preoperative platelet counts were independently associated with both intraoperative thrombosis (500 ± 120 versus 316 ± 144 × 10/liter; p < 0.001) and postoperative thrombosis (410 ± 183 versus 320 ± 143 × 10/liter; p = 0.040) in 215 patients who sustained acute lower extremity trauma within 30 days before reconstruction. In acute trauma patients, preoperative platelet counts predicted a four-fold increased risk of intraoperative thrombosis (cutoff value, 403 × 10/liter; OR, 4.08; p < 0.001) and a two-fold increased risk of postoperative thrombosis (cutoff value, 361 × 10/liter; OR, 2.16; p = 0.005). In patients who did not sustain acute trauma, preoperative platelet counts predicted a four-fold increased risk of intraoperative thrombosis (cutoff value, 352 × 10/liter; OR, 3.82; p = 0.002).

CONCLUSIONS

Acute trauma patients with elevated preoperative platelet counts are at increased risk for lower extremity free flap complications. Prospective evaluation is warranted for guiding risk stratification and targeted treatment strategies.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.