The miniaturized pediatric continuous-flow device: Preclinical assessment in the chronic sheep model.

BACKGROUND: The Infant Jarvik 2015 is an implantable axial-flow ventricular assist device (VAD) that has undergone the major evolutionary design modifications to improve hemocompatibility. This study was conducted in anticipation of data submission to the US Food and Drug Administration to obtain Investigational Device Exemption approval. METHODS: The VAD was implanted via a left thoracotomy in Barbado sheep (n = 10, 26 (19-34] kg). Anticoagulation was maintained with coumadin, with a target international normalized ratio of greater than the individual sheep's baseline values. The VAD was managed at the highest possible speed as clinically tolerable. Complete necropsy was performed at the end of the study. RESULTS: There were 2 early mortalities: tension pneumothorax (n = 1) and shower emboli of the fragmented myocardium (n = 1). The remaining 8 sheep (2 with 30-day and 6 with 60-day protocols) completed the anticipated study duration in excellent condition, with the 6 completing 60-day sheep showing appropriate weight gain during support. There were no signs of clinically significant hemolysis, with the final plasma-free hemoglobin of 2 (1-17) mg/dL. Necropsy showed old renal infarction in 7 sheep. Although thromboembolism can be the potential etiology, given the mild anticoagulation regimen, other sources of emboli were identified in 2 sheep (graft coating material and fragmented myocardium). Flow study demonstrated favorable increase in flow (up to 3.0 L/min) in proportion to change in pump speed. CONCLUSIONS: This study has demonstrated that the Infant Jarvik 2015 VAD is capable of maintaining its functionality for an extended period of time with minimal hemolysis.

In Vivo Evaluation of a Pneumatic Extracorporeal Ventricular Assist Device for up to 90 Day Support.

In a previous study, we showed that the Vitalmex Extracorporeal Ventricular Assist Device-Pneumatic (EVAD-P)-a low-cost, pneumatically actuated, pulsatile blood pump-is easy to implant and safe for short-term in vivo support (30 ± 5 days). In the current study, we included additional 30 day experiments and assessed the safety and durability of the EVAD-P for up to 90 days of support. Using the same surgical procedure as in the previous study, we implanted the device into 14 healthy sheep. Group I subjects (n = 7) were evaluated for up to 30 days, and group II (n = 2) and group III (n = 5) subjects were evaluated for up to 49 and 93 days, respectively. After a system redesign, two of the five sheep in group III reached the scheduled end-point without device-related problems at a fixed beat rate of 56 bpm, a stroke volume (SV) of 58.0 ± 2.3 ml, and a flow of 3.5 ± 0.2 L/min. This study shows that the EVAD-P can provide safe pulsatile mechanical circulatory support (MCS) for up to 93 days. To further confirm that the system can consistently provide MCS for this duration, additional studies are recommended.

Ninety-day survival of a calf implanted with a continuous-flow total artificial heart.

We evaluated the effects of steady state flow and perfusion on end-organ function in a long-term calf model. The animal received a continuous-flow total artificial heart (CFTAH) that we created from two axial-flow ventricular assist devices. Pump flow, blood pressure, and other pump parameters were monitored throughout the study, as were arterial blood gas and hematologic values, including neurohormone levels. Some hematologic values were mildly abnormal transiently after surgery but returned to acceptable levels within the first week. During the 90-day study, the calf showed no signs of hemolysis or thrombosis. Its mental function remained normal, as evidenced by the animal's interest in its surroundings and response to stimuli. End-organ and vasomotor function was not adversely affected by 90 days of steady state flow. This was the first study in which CFTAH support of an animal model was maintained for this duration.