Surface modifications for inflow cannulas of ventricular assist devices – comparison of latest solutions

Nowadays, the Mechanical Circulatory Support (MCS) within the Ventricular Assist Devices (VAD) appears to be a reliable and effective solution for patients with advanced heart failure (HF). After many years of work, extracorporeal pulsatile VADs have been replaced by new generations of implantable continuous flow (CF) pumps. Clinical experience has shown that present-day pump constructions still need to be improved to minimize the risk of complications during heart assistance. One of the complications is the pump inflow obstruction caused by the ingrowth of tissue into the blood inflow path and pump thrombosis. The main goal is to develop a coating for the external surface of the inflow cannula to provide controlled tissue ingrowth. The smooth surface of the cannula external wall results in the tissue overgrowth into the pump inflow orifice, and may be a source of emboli. The paper presents external surface modifications of the inflow cannula performed by different VAD manufacturers within the topography characterization. The inflow cannulas used in CF VADs are mainly made of titanium alloy due to its mechanical properties and high biocompatibility. In general, the discussed surface coatings were characterized by the roughness of about ≈ Ra = 15 μm, high porosity and good wettability Φ ≈ 60°. The surface was covered with titanium microspheres or titanium mesh. The developed surfaces and clinical experience confirm the ability to control the tissue ingrowth along the external surfaces of the inflow cannula at the tissue-implant interface

In-Vitro Biocompatibility and Hemocompatibility Study of New PET Copolyesters Intended for Heart Assist Devices

(1) Background: The evaluation of ventricular assist devices requires the usage of biocompatible and chemically stable materials. The commonly used polyurethanes are characterized by versatile properties making them well suited for heart prostheses applications, but simultaneously they show low stability in biological environments. (2) Methods: An innovative material-copolymer of poly(ethylene-terephthalate) and dimer linoleic acid—with controlled and reproducible physico-mechanical and biological properties was developed for medical applications. Biocompatibility (cytotoxicity, surface thrombogenicity, hemolysis, and biodegradation) were evaluated. All results were compared to medical grade polyurethane currently used in the extracorporeal heart prostheses. (3) Results: No cytotoxicity was observed and no significant decrease of cells density as well as no cells growth reduction was noticed. Thrombogenicity analysis showed that the investigated copolymers have the thrombogenicity potential similar to medical grade polyurethane. No hemolysis was observed (the hemolytic index was under 2% according to ASTM 756-00 standard). These new materials revealed excellent chemical stability in simulated body fluid during 180 days aging. (4) Conclusions: The biodegradation analysis showed no changes in chemical structure, molecular weight distribution, good thermal stability, and no changes in surface morphology. Investigated copolymers revealed excellent biocompatibility and great potential as materials for blood contacting devices