A Model to Evaluate Effect of Patient-Pump Mismatch on Thrombosis in a Pediatric Pulsatile Ventricular Assist Device

Purpose Thromboembolic events remain a common and significant complication of Berlin Heart (BH) EXCOR devices. Retrospective studies have found larger sized pumps in relation to body surface area (BSA) to be a risk factor, but this has not been demonstrated experimentally. We present a model to study the thrombogenic effects of patient-pump mismatch. Methods Two flow loops were constructed consisting of cardiopulmonary bypass tubing connecting graduated reservoirs to 10cc and 50cc BH's respectively, which were in turn connected to an Ikus driver (Figure 1A). Fresh ( Results Goal flow required pressure settings 160/-20 mmHg at 120 bpm for the 10cc BH vs. 120/-20 at 60bpm for the 50cc BH. Incomplete filling and emptying was noted on the 50cc Berlin. Dry thrombus weight was 36mg in the 10cc BH and 156mg in the 50cc BH. Qualitatively, deposits were noted primarily at the polyurethane valves in the 10cc BH. In contrast, the 50cc BH had deposits primarily in the tubing connectors (Figure 1B,C). Conclusion We demonstrate an effective model for detecting thrombogenic effects of patient-pump mismatch. This model paves the way for future studies focused on BSA's that are at the cusp of adjacent BH pump sizes.