Implantation of the Jarvik 2000 heart

Abstract

The axial-flow cardiac assist pump is an innovative type of implantable left ventricular assist system (LVAS) that offers a number of advantages over conventional, pulsatile systems. The axial-flow pump is significantly smaller than comparable pulsatile implantable pumps and requires no valvular mechanism. The constant flow of blood through the pump minimizes stasis and continuously washes the inorganic surfaces, reducing the likelihood of device thrombosis. The constant flow also obviates the need for a compliance chamber, so venting is unnecessary. Because the axial-flow pump is nonpulsatile, trauma related to movement of the driveline (an important potential source of infection) is significantly reduced. Whereas traditional LVASs necessitate a fairly extensive implant operation, the axial-flow pump is easier to implant, helping to minimize operative complications. As this LVAS has only 1 movable component, device reliability and durability are enhanced. The pump can be used to support children and smaller adults, as well as adults of usual size. In contrast to conventional, pulsatile LVASs, which are intended to capture the entire left ventricular output and, therefore, to serve as ventricular replacement devices, the axial-flow pump is best used as a true assist device. This article focuses on the Jarvik 2000 Heart (Jarvik Heart, Inc., New York, NY), an electrically powered LVAS that provides continuous flow from the left ventricle to the descending thoracic aorta. This pump is unique in that it can be placed within the left ventricle, thereby avoiding the rheologic problems (negative pressure stasis) associated with an inflow conduit. The Jarvik 2000 system, which has been described elsewhere (see Reference section) 1Myers TJ Gregoric I Tamez D et al.Development of the Jarvik 2000 Heart ventricular assist system.J Heart Failure Cire Support. 2000; 3: 133-140Google Scholar, 2Westaby S Banning AP Jarvik R et al.First permanent implant of the Jarvik 2000 Heart.Lancet. 2000; 356: 900-903Abstract Full Text Full Text PDF PubMed Scopus (117) Google Scholar, 3Frazier OH Myers TJ Gregorie ID et al.Initial clinical experience with the Jarvik 2000 implantable left ventricular assist system.Circulation. 2002; 105: 2855-2860Crossref PubMed Scopus (136) Google Scholar, 4Macris MP Myers TJ Jarvik R et al.In vivo evaluation of an electric intraventricular axial flow pump assist device.ASAIO J. 1994; 40: M719-M722Crossref PubMed Scopus (35) Google Scholar, 5Jarvik R Scott V Morrow M et al.Belt worn control system and battery for the percutaneous model of the Jarvik 2000 heart.Artif Organs. 1999; 23: 487-489Crossref PubMed Scopus (16) Google Scholar, 6Marlinski E Jacobs G Deirmengian C et al.Durability testing of components for the Jarvik 2000 completely implantable axial flow left ventricular assist device.ASAIO J. 1998; 44: M741-M744Crossref PubMed Scopus (15) Google Scholar, 7Jarvik R Westaby S Katsumata T et al.LVAD power delivery: A percutaneous approach to avoid infection.Ann Thorac Surg. 1998; 65: 470-473Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar consists of a blood pump, Dacron outflow graft (DuPont, Wilmington, DE), percutaneous power cable, pump-speed controller, and direct-current power supply (Fig I). Initial clinical studies have shown that the Jarvik 2000 can safely and satisfactorily support patients with severe heart failure who are awaiting transplantation. We describe the surgical technique that we use for implanting this LVAS. Before implanting the Jarvik 2000 pump, the operator should carefully inspect the device to verify that the bearings are intact and that none of the cable connections are cracked or broken. To confirm that the pump has not been damaged during shipment, it should be tested in a pitcher of saline solution. The driveline is then prepared for tunneling. The end of a 40-F Argyle chest tube is cut at an angle and is slit for approximately 6 cm. This will allow the operator to place the driveline inside the chest tube and thereby protect the connector during the tunneling procedure. The chest tube is secured to the driveline with umbilical tape. A finger cut from a sterile glove may be used to cover the pump inflow cannula and prevent contamination during passage. The pump is resubmerged in saline solution, where it is kept until the time of implantation. During the early postoperative period, hemodynamic function is assessed with an arterial pressure line, a pulmonary artery catheter, and transthoracic echocardiography. Ideally, the pump should be maintained at a speed that allows the aortic valve to open with ventricular unloading. This should prevent stasis and thrombotic complications in the aortic root. The presence of pulsatility alone does not ensure aortic valve opening. Rather, this is confirmed by observing the normal aortic pulse contour on the monitor. Pump flow is maintained at the lowest level compatible with a normal cardiac index. Routine hemodynamic and echocardiographic studies are conducted to determine the optimal pump-speed setting. During these tests, the pump speed is increased in 1,000-rpm increments over the usual operating range of 8,000 to 12,000 rpm, after which the pump is turned off for up to 5 minutes. Serial, complete 2-dimensional, M-mode, and Doppler echocardiographic studies are performed at 24 hours, at 1 week, at 1 month, and every 3 months thereafter. The Jarvik 2000 requires minimal routine care and maintenance. The lead-acid or lithium ion batteries are changed approximately every 12 hours. The pump speed generally remains constant but may be increased during exercise. These tasks become the patient's responsibility after he or she undergoes rehabilitation and training. Because of rapid advances in axial-flow technology, pumps such as the Jarvik 2000 are offering new hope to patients with congestive heart failure. The purpose of these devices is to augment left ventricular function rather than to assume it altogether. While the pump is in place, the constant blood flow through the pump ensures continuous left ventricular unloading. The role of anticoagulant therapy in Jarvik 2000 recipients is not yet clear. The pump's reduced thrombogenicity has been gratifying. It may be related to the ultra-smooth titanium surface, continuous blood flow, and minimal foreign-surface area. The Jarvik 2000 was designed to be reliable, easy to implant, and simple to operate, and we believe that these goals have been met. Implantation is less extensive and less time-consuming than with other implantable LVASs, so the rate of surgical complications, including serious hemorrhages and implant-related infections, is reduced. Patients and their caregivers find the system easy to operate. In our series of 22 patients, there have been no technical problems with system components. As experience with axial-flow pumps continues to accumulate, these devices can be expected to salvage an increasing number of terminally ill patients.