It has been suggested that pulsatile blood flow is superior to continuous flow in cardiopulmonary bypass (CPB). However, adoption of pulsatile flow (PF) technology has been limited due to practically and complexity of creating a consistent physiologic pulse. A pediatric pulsatile rotary ventricular pump (PRVP) was designed to address this problem. We evaluated the PRVP in an animal model, and determined its ability to generate PF during CPB. The PRVP (modified peristaltic pump, with tapering of the outlet of the pump chamber) was tested in 4 piglets (10-12kg). Cannulation was performed with right atrial and aortic cannulae, and pressure sensors were inserted into the femoral arteries. Pressure curves were obtained at different levels of flow and compared with both the animal's baseline physiologic function and a continuous flow (CF) roller pump. Pressure and flow waveforms demonstrated significant pulsatility in the PRVP setup compared to CF at all tested conditions. Measurement of hemodynamic energy data, including the percent pulsatile energy and the surplus hydraulic energy, also revealed a significant increase in pulsatility with the PRVP (p <0.001). PRVP creates physiologically significant PF, similar to the pulsatility of a native heart, and has the potential to be easily implemented in pediatric CPB.

Extracorporeal blood pumps are used as temporary ventricular assist devices or for extracorporeal membrane oxygenation. The ideal pump would be intrinsically self-regulating, carry no risk of cavitation or excessive inlet suction, be afterload insensitive, and valveless thus reducing thrombogenicity. Currently used technology, including roller, centrifugal, and pneumatic pulsatile pumps, does not meet these requirements. We studied a non-occlusive peristaltic pump (M-Pump) in two mock circulatory loops, and compared the performance to a frequently used centrifugal pump and a modified prototype of the M-Pump (the BioVAD). The simple resistance loop consisted of the investigated pump, a fixed height reservoir at 150 mmHg, and a variable inflow reservoir. The pulsatile circulation utilized a mock patient simulator with adjustable resistance elements connected to a pneumatic pulsatile pump. The M-Pump intrinsically regulated flow with changing preload, was afterload insensitive, and did not cavitate, unlike the centrifugal pump. The BioVAD also demonstrated these features, and could augment output with use of vacuum assistance. A non-occlusive peristaltic pump may be superior for short term extracorporeal circulatory assist by mitigating risks of excessive inlet suction, afterload sensitivity, and thrombosis.

Background Centrifugal pumps are increasingly used for temporary mechanical support for the treatment of cardiogenic shock. However, centrifugal pumps can generate excessive negative pressure and are afterload-sensitive. A previously developed modified roller pump mitigates these limitations both in vitro and in preliminary animal experiments. We report the results of intermediate-term testing of our evolving pump technology, known as BioVAD. Methods The BioVAD was implanted in 6 adult male sheep (62.5 ± 3.9 kg), with drainage from the left atrium and reinfusion into the descending aorta. The sheep were monitored for 5 days. Heparin was given during the initial implantation, but no additional anti-coagulation was given. Data collected included hemodynamic status, pump flow and pressures, laboratory values to monitor end-organ function and hemolysis, pathologic specimens to evaluate for thromboembolic events and organ ischemia, and explanted pump evaluation. Results All animals survived the planned experimental duration and there were no pump malfunctions. Mean BioVAD flow was 3.57 ± 0.30 L/min (57.1 cc/kg/min) and mean inlet pressure was -30.51 ± 4.25 mmHg. Laboratory values, including plasma free hemoglobin, creatinine, lactate, and bilirubin levels, remained normal. Three animals had small renal cortical infarcts, but there were no additional thromboembolic events or other abnormalities seen on pathologic examination. No thrombus was identified in the BioVAD blood flow path. Conclusions The BioVAD performed well for five days in this animal model of temporary left ventricular assistance. Its potential advantages over centrifugal pumps may make it applicable for short-term mechanical circulatory support.

Research is underway to develop a novel, low cost, disposable pediatric pulsatile rotary ventricular pump (PRVP) for cardiac surgery that provides a physiological flow pattern. This is believed to offer reduced morbidity and risk exposure within this population (1,2). The PRVP will have a durable design suitable for use in short-to mid-length prolonged support after surgery without changing pumps. The design is based on proprietary MC3 technology which provides variable pumping volume per stroke, thereby allowing the pump to respond to hemodynamic status changes of the patient. The novel pump design also possesses safety advantages that prevent retrograde flow, and maintain safe circuit pressures upon occlusion of the inlet and outlet tubing. The design is ideal for simple, safe and natural flow support.Computational methods have been developed that predict output for pump chambers of varying geometry. A scaled chamber and pump head (diameter=4 inches) were prototyped to demonstrate target performance for pediatrics (2 L/min at 100 rpm). A novel means of creating a pulsatile flow and pressure output at constant RPM was developed and demonstrated to create significant surplus hydraulic energy (greater than 10%) in a simplified mock patient circuit.

Background Blood pumps used for temporary circulatory support have limitations. We propose a novel device designed for short-term extracorporeal support which is intrinsically volume responsive, afterload insensitive, and incapable of cavitation or excessive hemolysis. After in vitro testing, we performed the initial in vivo implantations and assessments. Methods The BioVAD prototype (MC3, Inc, Ann Arbor, MI) was implanted in six adult male sheep (60.2 +/− 2.8 kg) via the left ventricular apex and descending thoracic aorta. Arterial, left and right atrial, pump inlet and outlet pressures and BioVAD flow were measured and recorded. The animals were volume loaded to assess volume responsiveness, and the inlet lines were abruptly clamped during maximum support to observe for cavitation. An acute heart failure model was created with rapid ventricular pacing, and the animals were supported for 4 hours. Results Peak flow was 3.19 +/− 0.56 L/min, and increased with 20 mmHg vacuum assisted drainage to 3.71 +/− 0.53 L/min. Without manual changes in pump settings, pump flow increased 17.5% with volume loading. During acute venous line occlusion, there was no evidence of cavitation and inlet suction was minimal. Hemodynamics were maintained for 4 hours during acute heart failure. Conclusions The BioVAD provided adequate flow in an acute in vivo model. Its design may be superior for short-term extracorporeal support.

Donation from uncontrolled circulatory determination of death donors (uDCD) is impractical in America because of the time needed to organize procurement before irreversible organ damage. Salvaging organs after prolonged warm ischemic time (WIT) may address this limitation. We evaluated the combination of extracorporeal support (ECS) and thrombolytics in a porcine uDCD renal transplant model. Non anti-coagulated uDCD sustained 60min of WIT, and two groups were studied. Rapid recovery (RR-uDCD), kidneys procured using rapid topical cooling; and ECS assisted donation (E-uDCD), 4hr ECS plus thrombolytics for in-situ perfusion prior to procurement. All kidneys were flushed and cold stored, followed by transplantation into healthy nephrectomized recipients without immunosuppression. Delayed graft function (DGF) was defined as creatinine>5.0mg/dL on any postoperative day. Twelve kidneys in E-uDCD and 6 in RR-uDCD group were transplanted. All 12 E-uDCD recipients had urine production and adequate function in the first 48hr, but two grafts (16.7%) had DGF at 96hr. All 6 recipients from RR-uDCD group had DGF at 48hr and were euthanized. Creatinine and BUN levels were significantly lower in E-uDCD compared to RR-uDCD group at 24hr (2.9±0.7mg/dL vs. 5.2±0.9mg/dL), and 48hr (3.2±0.9mg/dL vs. 7.2±1.0mg/dl); BUN levels at 24hr, (28.3±6.7mg/dL vs. 39.5±7.5mg/dL), and 48hr (23.9±5.0mg/dL vs. 46±12.9mg/dL) respectively. ECS plus thrombolytics precondition organs in-situ yielding functional kidneys in a porcine model of uDCD with 60 minutes of WIT. This procurement method addresses logistical limitations for uDCD use in the US, and could have a major impact on the organ donor pool.

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