Disclosures: Stephanie J. Rhynard, MD, DPT: Nothing to disclose

Case Description: AV is a 17-year-old male with a past medical history of previous pulmonary embolisms (recently off anticoagulation) and ROHHAD syndrome who presented to the hospital for shortness of breath and progressive lower extremity weakness. On admission, CT demonstrated a massive saddle pulmonary embolism, ECHO showed right heart strain, and Dopplers revealed a left lower extremity venous thrombosis. The patient was treated with right heart angiogram, suction thrombectomy, and left lower extremity mechanical thrombectomy with angioplasty and transferred to inpatient rehab (IPR).

Setting: Tertiary Care Hospital

Patient: 17-year-old male

Assessment/Results: On admission to the IPR physical exam was significant for morbid obesity and bilateral lower extremity paraparesis distally, worse on the left than the right. Pediatric hematology started subcutaneous Lovenox titrated based on anti-factor Xa level. The patient’s stay on IPR was complicated by acute left lower extremity swelling secondary to re-occlusion of the left femoral vein despite adequate anticoagulation. IV heparin was resumed and the patient transferred to the SICU for catheter directed thrombolysis. An extensive hypercoagulability workup resulted in pertinent negatives including factor V Leiden, prothrombin genotyping, SPEP without monoclonal proteins, and normal antiphospholipid antibody. CT abdomen pelvis with IV contrast to look for occult cancer was negative, and the work up remains in process.

Discussion: In a cursory literature review this is the first case of hypercoagulability in a patient with ROHHAD syndrome. Additionally, the incidence of venous re-occlusion on therapeutic Lovenox is rare. The significance of hypercoagulability in an already rare population is unclear, but this case teaches caution in presuming clots cannot occur when anti-factor Xa is in the therapeutic range.

Conclusion: Formation of clots while on therapeutic dosing of Lovenox is possible, and practitioners should keep clots in the differential even when patients are on anticoagulation. Additionally, as research into ROHHAD continues variants involving hypercoagulability should be considered.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/complete-femoral-vein-re-occlusion-on-therapeutic-lovenox-in-a-patient-with-rapid-onset-obesity-with-hypothalamic-dysregulation-hypoventilation-and-autonomic-dysregulation-rohhad-a-case-report/