AVAILABILITY:

The Levacor VAD™ is an Investigational Device. Limited by Federal (United States) Law to Investigational Use for a Bridge-To-Transplant Indication under an IDE Application. Not currently available outside the United States.

Overview

Levacor VAD™

MiVAD

Technologies

Levacor VAD™

System Configuration

Like the previously developed Novacor® LVAS, the Levacor VAD is implanted within the abdomen. Blood enters the pump through an inflow conduit connected to the recipient's left ventricle. The pump then ejects blood through an outflow conduit into the arterial system, thereby supporting the systemic circulation.

The Levacor VAD™ consists of an implanted centrifugal pump incorporating a magnetically levitated impeller (rotor), connected via a percutaneous lead to external electronics (See figure 1). The pump is implanted in a small left subcostal, preperitoneal space. The pump's titanium inflow cannula is inserted into the apex of the left ventricle. The outflow conduit, fabricated from a 12-mm diameter collagen-sealed woven polyester graft, is anastomosed to the ascending aorta.

Levacor System Configuration of Implantables and Wearables: Implanted pump Inflow cannula affixed to the LV apex Outflow conduit to ascending aorta Percutaneous lead Extension cable Controller, with internal reserve battery Battery Pack

Figure 1

The pump is enclosed within a titanium housing and incorporates smooth titanium blood-contacting surfaces. The outer surface of the inflow cannula's apical tip is covered with sintered titanium microspheres, creating a textured surface to promote fixation within the left ventricle. An apical cuff sewed on at the time of surgery attaches the inflow cannula to the native heart.

The small diameter percutaneous lead is covered with textured polyester cloth to promote tissue ingrowth where the lead exits the body. The percutaneous lead terminates in a connector shortly after it exits the body, plugging into an extension cable that, in turn, connects to a wearable controller. This extension cable, potentially vulnerable to wear or accidental damage, can be quickly replaced without surgical intervention.

External to the patient are wearables: a Controller (with internal reserve battery), and Battery Pack(s) (See figure 2).

External accessories to help patients manage power, and provide control (to physicians only), communication and monitoring are a Battery Charger, Base Unit, and a touch-screen display (See figure 3).

Other accessories are provided to:

1. help implant the Levacor VAD™ in a patient (surgical tools such as an apical coring knife and a percutaneous lead tunneling tool)
2. explant the device with an abdominal incision only, without requiring cardiopulmonary bypass, and
3. help improve the patient's quality of life, such as various carry bags for the contoller and battery pack, and a shower kit.

Controller (left) The Controller powers the implanted pump via the percutaneous lead. A selector switch allows the recipient or caregiver to choose among three pre-set impeller speeds. These speeds are set by the physician before discharge, to ensure that the pump speed remains within an appropriate range for that patient. Indicator lights communicate system status or alarm conditions. An audible alarm provides a further indication when user attention is required. Battery Pack (right) The Controller receives power either from a Battery Pack (during untethered operation) or from the power supply within the Base Unit (tethered operation). Incorporated within the Controller is a reserve battery, which supports pump operation while the primary power source (Battery Pack or Base Unit) is being changed or if it is accidentally disconnected.

Figure 2

Key external accessories available to each patient are:

	Monitor The Monitor is used both by the clinician and the patient. Control functions are enabled when used at the hospital, and disabled when taken home by the patient upon discharge from the hospital.
	Battery Charger This component can charge up to two rechargeable wearable battery packs at once.
	Base Unit The Base Unit is used both by the clinician and the patient and plugs into mains AC power to provide primary power to all Levacor system components when connected. It typically remains by the patient's bedside- both in and out of the hospital and can power the Wearable Controller instead of, or in addition to, a Wearable Battery Pack. The Base Unit also serves to coordinate communications between the Monitor and the Wearable Controller.

Figure 3

Anticipated Evolution
At present, the primary function of speed control is to provide a safe operating range for the pump for each patient. The Monitor displays an estimated flow rate. In the future, the Levacor's VAD physiologic control is being designed to allow detection of ventricular suction and eventually avoid ventricular suction while allowing some degree of self-regulation, which would automatically adjust the pump speed in response to the recipient's changing circulatory requirements.

The Levacor system is also planned to be available in an untethered configuration, in which the controller and a standby battery pack are implanted. A transcutaneous (across the skin) energy transfer (TET) system will eliminate wires through the skin, eliminating a potential cause of infection. WorldHeart anticipates using proprietary, existing TET technology, which incorporates both power transfer from the outside to inside the body, and bi-directional data transfer. This totally implantable configuration is shown in an artist's sketch to the right (Figure 4).

Figure 4