In Vivo Testing of a Novel Blood Pump for Short-Term Extracorporeal Life Support

Abstract

Purpose We developed a novel peristaltic-type blood pump that is preload-responsive and afterload-insensitive, generates minimal negative pressure, avoids cavitation, and can be augmented by vacuum-assisted drainage. The pump has previously been tested in vitro and in an in vivo model providing 4 hours of support. Our objective was to test the pump in a 4 to 5 day animal model, specifically examining its effects on hemolysis, thrombosis, and end-organ damage. Methods and Materials The pump was implanted in 4 adult male sheep (60.5±3.3kg) through a left thoracotomy, with drainage from the left atrium and reinfusion into the descending aorta. At the completion of the surgery, the sheep was extubated and supported for 4-5 days. Heparin was given during aortic cross-clamp (100 u/kg), but the sheep was not anticoagulated for the remainder of the study. Results Each of the 4 animals was instrumented without major complication. The sheep remained hemodynamically stable throughout the study, with mean arterial pressure of 104.08±9.19 mmHg. Average device flow was 3.42±0.24 L/min. The average pump inlet pressure was -28.39±3.15 mmHg. Plasma free hemoglobin levels decreased from a baseline of 2.03±1.52 mg/dL to 1.52±0.22 mg/dL at the completion of the study. Platelet levels slightly decreased from 244±179.32 K/μL to 174.25±111.55 K/μL. Creatinine levels remained stable from 1.00±0.18 mg/dL at baseline to 0.73±0.05 mg/dL at completion. Total bilirubin levels also remained stable, from 0.10±0 mg/dL to 0.175±0.10 mg/dL. Each animal survived without complication for the duration of the study (4-5 days), and was euthanized. On post-mortem necropsy, 1 animal had a renal infarct, but no other thromboembolic events or signs of organ damage were seen. Conclusions This pump can safely be implanted as a short-term extracorporeal support device for bridge to decision. It causes minimal hemolysis, thromboembolic phenomena, and organ damage. No manipulation of pump speed or suction is required, making it ideal for clinical use without the need for frequent adjustment by nursing.