Left ventricular assist devices LVADs

Wohlschlaeger J, Schmitz KJ, Schmid C, Schmid KW, Keul P, Takeda A, et al. Reverse remodeling following insertion of left ventricular assist devices (LVAD) a review of the morphological and molecular changes. Cardiovasc Res 2005 68 376-386. 

Current long-term mechanical support devices such as left ventricular assist devices (LVADs) require use of the heart lung machine and extensive surgery. The... 

Despite all these efforts, patients continue to die awaiting transplant. In 2001, over 6000 people died on transplant waiting lists. While renal dialysis may be used for an extended period of time to partially replace the function of the kidneys, such options are not readily available for all liver and heart transplant candidates. Hepato-cyte transplantation and artiflcal liver support are areas of research as alternatives or bridges to liver transplantation. Left-ventricular assist devices (LVADs) are now used commonly as a bridge to transplantation for many heart transplant candidates. 

Advances in numerous areas have allowed marked increases in survival times of artificial heart device (AHD) and left ventricular assist device (LVAD) experiments. Successful clinical trials employing LVAD s for temporary post-operative assistance after coronary surgical procedures have been reported by several centers (1). As clinical use of circulatory assist devices progresses, longer term (i.e., 3-4 months) implantations will be needed requiring not only initial surface hemocompatibility, but also long-term surface inertness or stability. 

For long-term circulatory support in patients with advanced CFIF (mostly as bridge-to-transplantation or bridge-to-recovery, rarely as destination therapy), a mechanical left ventricular assist device (LVAD) is often required, which decreases the left ventricular afterload by creation of a cardioaortic bypass through which the blood is directly pumped from the left ventricle into the aorta. In these patients MDCT not only allows for identification of the exact position of the carmula tip of the assist device, but may also allow for the detection of local complications associated with device implantation, such as intra/cardiac thrombosis, mediastinal, pericardial, or pleural fluid or air accumulations as well as mediastinal or pulmonary infections (Jain et al. 2005 Knollmann et al. 1999 Knisely et al. 1997). 

Medical treatment mainly includes external and implantable devices. External devices include iontophoresis, left ventricular assist devices (LVAD) or total artificial hearts (TAH), surgical implements, and dynamic prostheses [9]. 

Liotta (12) constructed his artificial heart from a combination of different materials - Lucite, teflon, polyester urethane, and silk. It is difficult to evaluate the thrombogenic potential of this combination of materials because the longest survival was 13 hours in dogs. The principle cause of death in these animals was low cardiac output secondary to inadequate venous return. The following year in a different series of experiments Liotta (13) tried a different combination of materials. Here, although the experiments were acute in scope, thrombus formation at the blood-plastic interface was a major problem. The left ventricular assist device (LVAD) was a tube-type with the housing and valves constructed of Estane. The internal elastic tube was made of either natural rubber. Silastic, or natural rubber covered externally with Silastic. 

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