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 After many years of work, extracorporeal pulsatile VADs have been replaced by new generations of implantable continuous flow (CF) pumps.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.