Design Concepts and Principle of Operation of the HeartWare Ventricular Assist System

Abstract

Implantable left ventricular assist devices provide circulatory support for patients at risk of death from refractory, end-stage heart failure. Rotary blood pumps have been designed for increased reliability and smaller size for use in a broader population of patients than the first-generation pulsatile devices. The design concepts and principle of operation of the HeartWare System are discussed. The HeartWare Ventricular Assist System (HVAD) is a small centrifugal flow pump with a displacement volume of 50 ml and an output capacity of 10 L/min. A unique wide-blade impeller is suspended by hybrid passive magnets and hydrodynamic forces. An integrated inflow cannula is inserted into the left ventricle and is held in position by an adjustable sewing ring; the pump is positioned in the pericardial space. The 10-mm outflow graft is anastomosed to the ascending aorta. External system components include the microprocessor-based controller, a monitor, lithium-ion battery packs, alternating current and direct current power adapters, and a battery charger. Physiologic control algorithms are incorporated for safe operation. Preclinical life cycle tests have shown the HVAD to be highly reliable. This system design offers reliability, portability, and ease of use for ambulatory patients.

Advantage of Pulsatility in Left Ventricular Reverse Remodeling and Aortic Insufficiency Prevention During Left Ventricular Assist Device Treatment

“…The HeartWare LVAD has a cyclic controlled speed change function (Lavare Cycle) mode, which allows for changes in LV filling and flow rate though the LVAD (ie, every minute during a 3-s cycle). 31 The HeartMate III LVAD has an induced pulse mode for achieving an increased level of pulsatility with CF assistance. 32 Preserving pulsatility during CF LVAD therapy may be the future direction for better LVRR and AI prevention.…”

The Tin Coatings Utilisation As Blood Contact Surface Modification In Implantable Rotary Left Ventricle Assist Device Religaheart Rot

“…The 2nd generation pumps (axial flow pumps mainly) have used mechanical sliding bearings [7]. The 3rd generation pumps (both axial and centrifugal pumps) are equipped with the non-contact physical bearings [8]. Each of the mentioned above bearing concepts has both advantages and disadvantages.…”

Current Options and Practices in Long-Term Ventricular Assist Devices

“…Its primary advantage is its intrapericardial placement, avoiding the need for an abdominal or pre-peritoneal pocket [35 • ]. The small design, with a displaced volume of only 50 ml, also allows for placement in smaller patients [23]. The centrifugal design allows it to achieve a maximum flow of 10 l/min at substantially lower RPMs than the axial design [35 • ].…”

“…Many LVADs, including the HeartMate II (Thoratec Corp., Pleasanton, CA), have an inflow conduit and outflow graft with a component of Dacron. The HeartWare HVAD (Heartware, Inc., Framingham, MA) is positioned intrapericardially and connected to the inflow cannula directly, eliminating the need for a surgical pocket [23]. The Jarvik 2000 (Jarvik Heart, Inc., New York, NY) is positioned intraventricularly with an outflow cannula out of the left ventricle to the ascending aorta [24].…”