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

Abstract

<jats:sec><jats:title>Objective</jats:title><jats:p> 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. </jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p> 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 ± 5 days and 2 animals were implanted for a duration of 90 ± 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. </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> 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 ± 139 RPM, 4.1 ± 0.4 L/min, and 4.3 ± 0.1 W, respectively. Examination of pump components postexplant demonstrated no mechanical wear or thrombus formation. </jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p> Hemocompatibility and biocompatibility of the modified MVAD System were demonstrated through pump parameters, blood chemistry panels, and histopathology analysis. </jats:p></jats:sec>

Debate

“…(2) In the Heartware-MVAD a periodic speed change named 'q-pulse' was implemented [8], speed reduction of 15 or 20% for 5 s, followed by a return to the set speed for either 10 or 30 s, which because of its timing is intended to facilitate aortic valve opening (AVO) and to cause some arterial pulsatility. (3) In the Heartmate-III, a speed change named 'artificial pulse' has been implemented [9].…”

Dynamic measurement of centering forces on transvalvular cannulas

“…An established therapeutic option for patients with heart failure is the implantation of a ventricular assist device (VAD). Current developments of new VADs aim toward reduced surgical invasiveness by alternative surgical approaches and miniaturized devices . Miniaturized pumps might be directly implanted into the cardiac chamber or the aorta and provide circulatory support in heart failure .…”

A Novel Control Method for Rotary Blood Pumps as Left Ventricular Assist Device Utilizing Aortic Valve State Detection

“…Considering the importance and necessity of detecting and maintaining an open state of the aortic valve some companies have incorporated controllers in their devices for the control of aortic valve opening based on intermittent decreasing pump speed to a predefined set point [17, 24]. However, these algorithms do not know the current state of the valve during speed changes.…”