Mechanical circulatory assistance

Real time visualization and characterization of platelet deposition under flow onto clinically relevant opaque surfaces

Although the thrombogenic nature of the surfaces of cardiovascular devices is an important aspect of blood biocompatibility, few studies have examined platelet deposition onto opaque materials used for these devices in real time. This is particularly true for the metallic surfaces used in current ventricular assist devices (VADs). Using hemoglobin depleted red blood cells (RBC ghosts) and long working distance optics to visualize platelet deposition, we sought to perform such an evaluation. Fluorescently labeled platelets mixed with human RBC ghosts were perfused across six opaque materials (a titanium alloy (Ti6Al4V), silicon carbide (SiC), alumina (Al2O3, 2-methacryloyloxyethyl phosphorylcholine polymer coated Ti6Al4V (MPC-Ti6Al4V), yttria partially stabilized zirconia (YZTP), and zirconia toughened alumina (ZTA)) for 5 min at wall shear rates of 400 and 1000 s(-1). Ti6Al4V had significantly increased platelet deposition relative to MPC-Ti6Al4V, Al2 O3 , YZTP, and ZTA at both wall shear rates (p < 0.01). For all test surfaces, increasing the wall shear rate produced a trend of decreased platelet adhesion. The described system can be a utilized as a tool for comparative analysis of candidate blood-contacting materials with acute blood contact.

Management of advanced heart failure in the elderly: ethics, economics, and resource allocation in the technological era

Significant strides have been made in the durability, portability, and safety of mechanical circulatory support devices (MCS). Although transplant is considered the standard treatment for advanced heart failure, limits in organ availability leave a much larger pool of recipients in need versus donors. MCS is used as bridge to transplantation and as destination therapy (DT) for patients who will have MCS as their final invasive therapy with transplant not being an option. Despite improvements in quality of life (QOL) and survival, defining the optimal candidate for DT may raise questions regarding the economics of this approach as well as ethical concerns regarding just distribution of goods and services. This paper highlights some of the key ethical issues related to justice and the costs of life-prolonging therapies with respect to resource allocations. Available literature, current debates, and future directions are discussed herein.