Design Concepts and Preclinical Results of a Miniaturized HeartWare Platform: The MVAD System

Abstract

Objective: Ventricular assist device (VAD) miniaturization is one design trend that may result in less-invasive implantation techniques and more versatility with patient selection. The MVAD System is a miniature, continuous-flow device implanted in the ventricle. The pump is capable of delivering between 0 and 7 L/min of flow at a mean arterial pressure of 75 mm Hg. The impeller was optimized from its original design to improve hydraulic performance, minimize shear regions, and enhance the impeller's radial stiffness. These studies evaluated the MVAD System with modified impeller in the preclinical setting. Methods: This modified pump design was tested through chronic studies (n = 6) in a healthy ovine model where 4 animals were implanted for a duration of 30 T 5 days and 2 animals were implanted for a duration of 90 T 5 days. The pump was placed in the left ventricular apex with the outflow graft anastomosed to the descending aorta. Postoperatively, no anticoagulant or antiplatelet therapies were administered throughout the study duration. Results: All 6 animals reached their elective date of kill, demonstrating no evidence of organ compromise or device-related complications. Average pump parameters did not deviate significantly, and average rotational speed, pump flow, and power consumption were 14095 T 139 RPM, 4.1 T 0.4 L/min, and 4.3 T 0.1 W, respectively. Examination of pump components postexplant demonstrated no mechanical wear or thrombus formation. Conclusions: Hemocompatibility and biocompatibility of the modified MVAD System were demonstrated through pump parameters, blood chemistry panels, and histopathology analysis.

The Progress in the Novel Pediatric Rotary Blood Pump Sputnik Development

“…Apart from the development of pediatric VADs in current cardiac surgery, miniaturization of VADs designed for adult patients has been actively pursued . Decreased weight and size leads to increases in patients' mobility and reduces the degree of invasiveness and the time spent by the patient in clinic post‐implantation.…”

“…Small size and short integrated inflow cannula allow for pericardial placement of the MVAD pump. Ovine model chronic studies demonstrated excellent biocompatibility and hemocompatibility of the MVAD pump . Another VAD being miniaturized for pediatric patients is the low‐shear pulsatile TORVAD system (Windmill Cardiovascular Systems, Inc, Austin, TX, USA).…”

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

“…As far as we know, all the previous animal studies on VAD development did not induce heart failure before VAD implantation. 3,[13][14][15] The fact that the VAD is implanted in hearts with normal dimension also has an important implication to the selection of animal size to choose for the study. We used the Barbado sheep, with a weight of approximately 20 to 30 kg.…”

“…Renal infarction occurs frequently during long-term animal studies testing VADs. 14,15 In the absence of histologically confirmed renal intravascular thrombus, determining the etiology of such infarcts remains speculative. In this study, 7 of the 10 sheep had visible pale lesions in the kidneys consistent with old infarcts.…”

Clinical overview of the HVAD: a centrifugal continuous-flow ventricular assist device with magnetic and hydrodynamic bearings including lateral implantation strategies

“…A potentially optimized version of the HVAD pump has already been produced by HeartWare, termed MVAD and is currently being tested preclinically (34,35). The MVAD pump is a continuous axial flow pump and similar to the HVAD, it possesses "contactless" impeller suspension technology, supporting a wide range of flow rates.…”