At the core of the HeartWare Left Ventricular Assist System is a small implantable centrifugal blood pump called the HVAD^TM Pump.  The pump is designed to draw blood from the apex of the left ventricle and to propel it through an outflow graft connected to the patient's ascending aorta.  The device is capable of generating up to 10 liters per minute of blood flow. 

With a displaced volume of only 50cc, the HVAD^TM pump is designed to be implanted in the pericardial space, directly adjacent to the heart.  Implantation above the diaphragm is expected to lead to relatively short surgery time and relatively quick recovery.

The HVAD^TM Pump has only one moving part, the impeller, which spins at rates between 2,000 and 3,000 revolutions per minute.  The impeller is suspended within the pump housing through a combination of passive magnets and a hydrodynamic thrust bearing.  This hydrodynamic suspension is achieved by a gentle incline on the upper surfaces of the impeller blades.  When the impeller spins, blood flows across these inclined surfaces, creating a "cushion" between the impeller and the pump housing.  There are no mechanical bearings or any points of contact between the impeller and the pump housing.

Device reliability is enhanced through the use of dual motor stators with independent drive circuitry, allowing a seamless transition between dual and single stator mode if required.  The pump's inflow cannula is integrated with the device itself, ensuring proximity between the heart and the pumping mechanism.  This proximity is expected to facilitate ease of implant and to help ensure optimal blood flow characteristics.  The use of a wide-bladed impeller and clear flow paths through the system are expected to help minimize risk of pump induced hemolysis (damage to blood cells) or thrombus (blood clotting).

How does the HeartWare Ventricular Assist System Work?

The HeartWare's Ventricular Assist System is designed to help a patient's weakened heart pump blood throughout his or her body by removing blood from the left side of the heart and pumping the blood into the aorta (the large blood vessel that carries blood from the heart to the rest of the body).  The pump is designed to rest inside the patient's chest.  Two small motor stators inside the pump housing cause an impeller within the device to rotate, pumping blood through the system.  A driveline (cable) exits the patient's skin and connects the implanted pump to an externally worn controller.  The controller is powered by a battery pack, which incorporates two batteries or one battery plus an adaptor connecting to a wall or vehicle electricity outlet.  The controller operates the pump and is designed to provide the patient with signals and alarms concerning the operation of the system.  The controller and batteries are contained in a carrying case that is designed to be worn either on the patient's belt or over the shoulder.

The individual components of the system are shown below.

HVADTM Pump		The Pump (LVAD) is designed to be surgically implanted above the diaphragm, directly adjacent to the heart.
HeartWareTM Controller		The Controller is designed to provide control signals to drive the pump and also to provide feedback and alarms to the patient regarding the operation of the device.
HeartWareTM Battery		The Battery is used to power the pump. Two batteries or one battery and an AC Adapter or DC Adapter are always required. When the battery is depleted (after approximately 6 hours) the system automatically switches to the standby battery and the depleted battery must be replaced.
HeartWareTM Battery Charger		The Battery Charger charges and tests the batteries. The battery charger is able to charge up to four batteries simultaneously.
Patient Pack		The Patient Pack is a carrying case that holds the controller and 2 batteries. The case is designed to be carried over the shoulder or worn on the patient's belt.
HeartWareTM Controller AC Adapter		The AC Adapter uses power from an electrical outlet to power the controller.
HeartWareTM Controller DC Adapter		The DC Adapter uses power from an electrical outlet in a motor vehicle to power the controller.
Alarm Adapter		The Alarm Adapter is a small red adapter inserted into the controller when it is powered down.

HVADTM System Surgical Tools

HeartWare has designed a set of customized surgical tools and accessories to facilitate implantation of the HVAD^TM device.  These are single-use surgical tools, a full set of which is included with each pump kit.  The surgical accessories include:

• An Apical Coring Tool to core the myocardium for left ventricular cannulation;
• A Sewing Ring Tool, which is used to tighten the screw on the Apical Ring; and
• A Tunneler, which is used to tunnel the percutaneous driveline from the pump through the exit site.