BIO17: Diurnal Variation of Operational Data in Preclinical Evaluation of a Continuous Flow Intra-aortic Blood Pump

Abstract

Background: The Aortix pump (Procyrion Inc.) is a percutaneously deployed mechanical circulatory support (pMCS) device positioned in the descending thoracic aorta above the renal arteries. The device is undergoing clinical trials to treat cardio-renal syndrome for up to 7 days. A longer implant providing sustained reduction of cardiac afterload and additional hemodynamic benefit may promote cardiac rest and reverse remodeling and offer a minimally invasive bridge-to-recovery therapy. Methods: To evaluate long-term safety, 4 devices were implanted in untethered sheep for 90-142 days. Animals wore support vests to carry the pump controller and battery and were administered twice-daily subcutaneous enoxaparin. All animals were electively terminated. In addition to clinical pathology, pump speed and current were monitored at 5 Hz. The data was reviewed with a 30-minute mean down-sampling to facilitate analysis of longer duration phenomenon. Results: There was no evidence of kidney or vascular damage, aortic adhesion, clinically significant hemolysis, or infection. A novel observation was made in the recorded pump data. In all 4 animals, a small but regular variation in pump current was noted which correlates to diurnal periods of higher animal activity during the day (feeding, handler care) and lower activity overnight. The median half-hourly current varies as much as 1.5% above and below the mean of the two-week sample period (Figure 1). Conclusion: This novel observation of pump current variation underscores the link between operation and performance of a pMCS device and physiologic characteristics of the implanted subject. Further refinement of such techniques may present new avenues for monitoring patient activity, hemodynamics, and state of therapy which could be used to improve the standard of care. Future work may investigate similar phenomenon from in vivo clinical use of the Aortix device.Figure 1. For each animal, current is shown as the median current for each 30-minute window over a representative 14-day period relative to the mean current over the same period.