Thoratec Corporation Research Articles

Implantation of the Thoratec Ventricular Assist Device

The Thoratec ventricular assist device (VAD) (Thoratec Corporation, Pleasanton, CA) has been extensively used as the standard therapy for bridge-to-transplant and postcardiotomy failure to wean from cardiopulmonary bypass.1 Recent clinical data suggest that myocardial recovery and improved cardiac function occur in some patients over a period of weeks to months of mechanical ventricular support, allowing removal of the VAD.2 Long-term studies of patients with the Thoratec VAD who recovered and were weaned from the device showed that 1- and 5-year survival rates were essentially identical to VAD patients who received a heart transplant.

Use of autologous auricular chondrocytes for lining artificial surfaces: a feasibility study

Background. Auricular elastic cartilage is a potential source of autologous cells for lining the luminal surfaces of cardiovascular prostheses. We tested this potential in vitro and in vivo using a left ventricular assist device (LVAD) and a calf model. Methods. In vitro, auricular cartilage was harvested from the anesthetized ear of a calf, isolated, and cultured on tissue culture dishes. Primary chondrocytes were typed by immunocytochemistry, transferred into culture media, passaged twice, and seeded onto the blood-contacting luminal surfaces of four LVADs (HeartMate; Thoratec Corporation, Woburn, MA). Seeded cell linings were preconditioned under simulated flow conditions to promote cell adhesion to luminal surfaces. Seeding efficiency and cumulative cell loss under flow conditions were quantitated. In vivo, one of the four autologous chondrocyte-lined and preconditioned LVADs was implanted into the tissue-donor calf; run for 7 days; explanted; and evaluated grossly, by scanning electron microscopy, and by transmission electron microscopy. Results. The efficiency of seeding chondrocytes onto the luminal surfaces of the four LVADs was 95.11% ± 4.23% (n = 4). Cumulative cell loss during preconditioning under flow conditions in vitro did not exceed 12% (n = 4). After 7 days of in vivo implantation, the luminal surfaces of the implanted LVAD demonstrated an intact, strongly adherent cellular lining. Conclusions. Auricular elastic cartilage is a ready and easily accessible source of chondrocytes whose ability to produce collagen II and other important extracellular matrix constituents allows them to adhere strongly to the luminal surfaces of LVADs. The simple method of isolating and expanding auricular chondrocytes presented here could be used to provide strongly adherent autologous cell linings for LVADs and other cardiovascular devices. If and when chondrocytes can be genetically engineered to produce antithrombogenic factors and then used to line the luminal surfaces of LVADs or other cardiovascular prostheses, they may be able to improve the hemocompatibility of the blood–biomaterial interface in such devices. Our successful feasibility study in a calf model warrants further studies of this concept in vivo.

Education of the ventricular assist device patient's community services.

Two implantable, electric left ventricular assist systems have received approval from the Food and Drug Administration (FDA) for use outside a hospital environment. As patients supported with these systems are discharged from the hospital, it is important that various community services and agencies be involved in the care of this unique patient population. Between January 1999 and May 2001, The University of Iowa Hospitals and Clinics (UIHC) implanted 14 HeartMate VE LVAS (Thoratec Corporation, Pleasanton, CA) in patients as a bridge to cardiac transplantation. Of these 14 patients, 13 were discharged home from the hospital. On the basis of our 3 year experience, a discharge program has been developed to educate the ventricular assist device (VAD) patient's community services. Ten community services most critical to a safe home discharge program are identified. Timing of service contact, mechanism of contact, community education method, education content, education materials, and outpatient community service usage are described.