LVAD pannus complicating destination therapy

Biological Response to Sintered Titanium in Left Ventricular Assist Devices: Pseudoneointima, Neointima, and Pannus

Titanium alloys have traditionally been used in blood-contacting cardiovascular devices, including left ventricular assist devices (LVADs). However, titanium surfaces are susceptible to adverse coagulation, leading to thrombogenesis and stroke. To improve hemocompatibility, LVAD manufacturers introduced powder sintering on blood-wetted surfaces in the 1980s to induce endothelialization. This technique has been employed in multiple contemporary LVADs on the pump housing, as well as the interior and exterior of the inflow cannula. Despite the wide adoption of sintered titanium, reported biologic response over the past several decades has been highly variable and apparently unpredictable-including combinations of neointima, pseudoneoimtima, thrombus, and pannus. We present a history of sintered titanium used in LVAD, a review of accumulated clinical outcomes, and a synopsis of gross appearance and composition of various depositions found clinically and in animal studies, which is unfortunately confounded by the variability and inconsistency in terminology. Therefore, this review endeavors to introduce a unified taxonomy to harmonize published observations of biologic response to sintered titanium in LVADs. From these data, we are able to deduce the natural history of the biologic response to sintered titanium, toward development of a deterministic model of the genesis of a hemocompatible neointima.

Outcomes With Left Ventricular Assist Device in End-Stage Renal Disease: A Systematic Review

Renal dysfunction is a common comorbidity in patients with advanced heart failure who may benefit from mechanical circulatory support (MCS). Unfortunately, renal function may result after left ventricular assist device (LVAD) implantation. The purpose of this study is to examine the outcomes of advanced heart failure patients with end-stage renal disease (ESRD) requiring mechanical circulatory support as a bridge to transplant (BTT) or destination therapy (DT). We searched Medline, Embase, and Cochrane in September 2021. The following keywords were used: left ventricular assist device or LVAD and end-stage renal disease or ESRD. Our study included case reports, case series, descriptive studies, and randomized control trials. Review articles, guidelines, systematic reviews, and meta-analyses were excluded. We also excluded pediatric cases. We identified 278 articles; 92 were duplicated, 186 articles entered the screening phase, and 133 articles were excluded by title and abstract. After the full-text screening, 40 articles were excluded. This systematic review included 13 articles. Among the contraindications to LVAD implantation, a general contraindication is for patients found to have stage 4 chronic kidney disease (CKD) (estimated glomerular filtration rate (eGFR): <30 mL/minute/1.73 m2), while those on dialysis are an absolute contraindication LVAD implantation. Despite the limited data and publications on LVADs in patients with ESRD, LVAD implantation as a bridge to transplantation or destination therapy may be considered in selected patients without increasing morbidity and mortality. Therefore, shared decision-making around the treatment of advanced heart failure with these patients and the care team is essential.

Tipless transseptal cannula concept combines improved hemodynamic properties and risk-reduced placement: An in silico proof-of-concept

As a leading cause of death worldwide, heart failure is a serious medical condition in which many critically ill patients require temporary mechanical circulatory support (MCS) as a bridge-to-recovery or bridge-to-decision. In many cases, the TandemHeart system is used to unload the left heart by draining blood from the left atrium (LA) to the femoral artery via a transseptal multistage cannula. However, even though the correct positioning of the cannula is crucial for a safe treatment, the long cannula tip currently used in transseptal cannulas complicates positioning, making the cannula vulnerable to displacement during MCS. To overcome these limitations, we propose the development of a new tipless transseptal cannula with improved hemodynamic properties. We discuss the tipless cannula concept by comparing it to the common multistage cannula concept using computational fluid dynamics simulations and assess the flow field in the LA, the wall shear stresses (WSS), and the pressure loss. Across the two distinct time points of end-systole and end-diastole and two drainage flow rates of 3.5 and 5.0 L/min, we find a more homogeneous inlet flow pattern for the tipless cannula concept, accompanied by a remarkably reduced area of platelet-activating WSS (up to 10-times smaller area compared to the multistage cannula). Moreover, pressure loss is up to 14.5% lower in the tipless cannula concept, confirming overall improved hemodynamic properties of the tipless cannula concept. Finally, a diameter-dependent study reveals that lower WSS and pressure losses can be further reduced by large-lumen designs for any simulation setting. Overall, our results suggest that a tipless cannula concept remedies the crucial disadvantages of a long-tip multistage cannula by reducing the risk of misplacement, and it furthermore promotes optimized hemodynamics. With this successful proof-of-concept, we underscore the potential for and encourage the realization of further experimental investigations regarding the development of a tipless transseptal cannula for MCS.