EXCOR® Pediatric VAD Anticoagulation IDE

Inclusion Criteria: 1. Severe heart failure (NYHA functional class IV, or Ross functional class IV if \< age 6 years of age), refractory to optimal medical therapy 2. Patient deemed to be candidate for EXCOR implantation according to the clinical criteria employed by treating site 3. Listed or eligible for cardiac transplantation according to the criteria employed by the treating site 4. Two-ventricle circulation, including cardiomyopathy, repaired structural heart disease, or acquired heart disease 5. Age 0 to 18 years of age 6. Corrected gestational age ≥ 37 weeks 7. Weight ≥ 3 kg and ≤ 60 kg 8. Legal guardian (and patient if age-appropriate) understands the nature of the investigation, is willing to comply with the protocol and associated evaluations, and provides written informed consent and assent prior to the procedure. \- Exclusion Criteria: 1. Support on ECMO for ≥10 days 2. Cardiopulmonary resuscitation (CPR) duration ≥ 30 minutes within 48 hours prior to device implantation 3. Body weight \< 3.0 kg or BSA \> 1.5 m2 4. Presence of mechanical aortic valve 5. Unfavorable or technically-challenging cardiac anatomy including single ventricle lesions, complex heterotaxy, and restrictive cardiomyopathy. 6. Evidence of intrinsic hepatic disease as defined by a total bilirubin level or ALT greater than 5 times the upper limit of normal for age, except in association with acute heart failure as determined by the site principal investigator 7. Evidence of intrinsic renal disease as defined by a serum creatinine greater than 3 times the upper limit of normal for age, except in association with acute heart failure as determined by the investigator 8. Hemodialysis or peritoneal dialysis (not including dialysis or continuous veno-venous hemofiltration (CVVH) for volume removal) 9. Evidence of intrinsic pulmonary disease (eg chronic lung disease, or ARDS) as defined by need for positive pressure ventilation, except in association with acute heart failure as determined by the principal investigator 10. Moderate or severe aortic and/or pulmonary valve insufficiency considered technically challenging to repair at the time of the device implantation as determined by the principal investigator 11. Apical VSD or other hemodynamically-significant lesion considered technically challenging to repair at the time of device implantation as determined by the principal investigator 12. Documented heparin induced thrombocytopenia (HIT) or idiopathic thrombocytopenia purpura (ITP) or other contraindication to anticoagulant/antiplatelet therapy 13. Documented coagulopathy (e.g. Factor VIII deficiency, disseminated intravascular coagulation) or thrombophilic disorder (e.g. Factor V Leiden mutation) 14. Hematologic disorder causing fragility of blood cells or hemolysis (e.g. sickle cell disease) 15. Platelets \< 70,000/ml within 24 hours prior to device implantation 16. Active infection within 48 hours of implant (positive blood culture OR temperature \> 38 degrees C AND wbc \> 15,000/ml) 17. Documented human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS) 18. Evidence of recent or life-limiting malignant disease 19. Stroke within past 30 days prior to enrollment, or congenital CNS malformation syndrome associated with increased risk of bleeding (e.g. arteriovenous malformation, moya moya) 20. Psychiatric or behavioral disease (e.g. antisocial disorder) with a high likelihood for non-adherence to the protocol and follow-up 21. Currently participating in another investigational device or drug trial and has not completed the required follow-up period for that study. EXCEPTION: Dual enrollment in PUMPKIN study is permitted. 22. Patient is pregnant or nursing \-