Heart mechanical circulatory support

Dipla K, Mattiello JA, Jeevanandum V, Houser SR, Margulies KB. Myocyte recovery after mechanical circulatory support in humans with end-stage heart failure. Circulation 1998 97 2316-2322... 

Owing to his tireless efforts, Brano became Associate Director of Transplant Research in 1998 and Director of the Center for Cardiac Support in 2005. In the latter capacity, he lectured and traveled extensively, sharing his knowledge and expertise about mechanical circulatory support, heart transplantation, and other heart failure therapies with colleagues and friends. 

Stage D heart failure includes patients with symptoms at rest that are refractory despite maximal medical therapy. This includes patients who undergo recurrent hospitalizations or cannot be discharged from the hospital without special interventions. These individuals have the most advanced form of heart failure and should be considered for specialized therapies, including mechanical circulatory support, continuous positive inotropic therapy, cardiac transplantation, or hospice care. The approach to treatment of patients with stage D heart failure is discussed in more detail in the section Treatment Advanced/ Decompensated Heart Failure. ... 

The most commonly used means of mechanical circulatory support is the intra-aortic balloon pump (lABP). In 1990, it was estimated that lABP therapy was provided to 70,000 patients aimually (Kantrowitz, 1990). As described below, the lABP can provide only limited cardiovascular support, as its effects are limited to pressure unloading of the ventricle, in contrast to artificial hearts and ventricular assist devices, which provide volume unloading (Mehlhom et al., 1999). To be effective, the lABP requires that the patient maintain some native pumping capacity, as the movement of blood due to the balloon is minimal. 

The indications for implantation of TAHs and VADs are similar to those for the lABP. but are usually reserved for patients who have failed balloon pump support and/or maximal medical therapy. Current FDA-approved VADs are placed for postcardiotomy support or as a bridge to either transplantation or recovery (Willman et al., 1999). Investigators are also evaluating chronic mechanical circulatory support as an alternative to transplantation for patients who do not meet the criteria to become a donor heart recipient (Rose et al., 1999). 

If there is dear evidence of worsening prompt hospital admission for intensive therapy is necessary. As the availability of a suitable donor heart is not predictable, hemodynamic deterioration is first treated with intravenous inotropic support. When the low-cardiac-output syndrome continues to be refractory, patients are put on a mechanical circulatory device for temporary mechanical support. This bridge to transplantation concept enables patient stabilization, withdrawal of intravenous medication (inotropic agents, catecholamines, calcium sensitizers) and rehabilitation (Antretter et al. 2002a). During chronic mechanical circulatory support a low level of exercise is possible and the patients are able to walk around, to leave hospital and sometimes they are followed up by heart failure specialists in an outpatient clinic. Nearly 25% of the most recent cohort transplanted from 1 January, 2001 to 30 June, 2003 were on some type of mechanical circulatory support (Taylor et al. 2004). 

Rosenberg, G. 1991. Technological opportunities and barriers in the development of mechanical circulatory support systems (Appendix C). In Institute of Medicine, The Artificial Heart, Prototypes, Policies, and Patients, ed J. R. Hogness and M. VanAntwerp, 211-250. Washington, DC National Academy Press. 

Treatment strategies for progressive pulmonary venous hypertension should focus on treatment of the underlying disease. For patients with advanced decompensated systolic heart failure and secondary pulmonary hypertension, it is essential to reduce the pulmonary vascular resistance prior to heart transplantation to prevent acute RV failure of the donor heart. The use of continuous milrinone, occasionally nesirit-ide, and earlier intervention with mechanical circulatory device support (19) as a bridge to cardiac transplantation is considered a standard approach for this group of patients. Earlier intervention with valve repair or replacement for patients with mitral valve disease and aortic valve disease with associated pulmonary hypertension is recommended. 

Starling RC, Naka Y, Boyle AJ, et al. Results of the post-U.S. Food and Dmg Administration-approval study with a continuous flow left ventricular assist device as a bridge to heart transplantation a prospective study using the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support). JAm Coll Cardiol May 2011 57(19) 1890-8. 

The second approach involves the injection of isolated exogenous cells. For example, pluripotent stem cells have been injected into the circulatory system or directly into the heart. Furthermore, embryonic stem cells, skeletal myoblasts, skeletal muscle-derived multimyogenic stem cells, unselected bone marrow stem ceUs, mesenchymal stem cells, endothelial precursor cells, " and adult cardiac stem cells have been shown to differentiate into cardiac phenotypes. Though improved cardiac function has been reported, the underlying mechanism is not clear and the survival rates of the cells tend to be extremely low. This is probably due to the lack of local support for the cells to grow and establish themselves. 

Several systems are now available for circulation support. Ventricular assist devices (VAD) are mechanical pumps that can take over the circulatory function of the left ventricle (LVAD), the right ventricle (RVAD) or both ventricles (biventricular assist device - BVAD). The patient s native heart remains in place, and the VADs are implanted in a heterotopic position. Connection between the heart chambers and the great vessds is usually achieved... 

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