Optical Dynamic Analysis of Thrombus Inside a Centrifugal Blood Pump During Extracorporeal Mechanical Circulatory Support in a Porcine Model

Abstract

Complications due to pump thrombus remain the weak point of mechanical circulatory support (MCS), such as the use of a left ventricular assist device (LVAD) or extracorporeal membrane oxygenation, leading to poor outcomes. Hyperspectral imaging (HSI) is an effective imaging method using a hyperspectral (HS) camera, which comprises a spectrophotometer and a charge-coupled device camera to discriminate thrombus from whole blood. Animal experiments were conducted to analyze dynamic imaging of thrombus inside a prototype of a hydrodynamically levitated centrifugal blood pump using an HSI system. Six pigs were divided into a venous circulation group (n = 3) and an arterial circulation group (n = 3). Inflow and outflow cannulae were inserted into the jugular veins in the venous circulation group. The latter simulated an LVAD application. To create thrombogenic conditions, pump flow was maintained at 1 L/min without anticoagulation. An image of the bottom surface of the pump was captured by the HS camera every 4 nm over the wavelength range of 608-752 nm. Real-time dynamic images of the inside of the pump were displayed on the monitor. Appearance of an area displaying thrombus was detected within 24 h after the start of the circulation in every experiment. This imaging system also succeeded in determining the origins of pump thrombus: from inside the pump in two cases, and from outside in four cases. Two main possible sources of pump thrombus originating outside the pump were identified on autopsy: wedge thrombus around the inflow cannula; and string-like thrombus at the junction between the pump inlet and circuit tube. The results of this study from close observation of the changing appearance of pump thrombus may contribute to improvements in the safety of extracorporeal MCS.

Flow Characteristics and Coherent Structures in a Centrifugal Blood Pump

“…The complications are associated with blood damage including increased risk of hemolysis, activation of platelets, thrombosis and emboli. Thrombus have been observed in tubing connectors, cannulae, at the entrance of the oxygenator as well as in the blood pumps [4][5][6][7]. Regarding blood pumps, thrombus formation and hemolysis have been reported to be induced independent of the type of the pump (i.e axial, roller or centrifugal) [4,8,9].…”

Plasma skimming efficiency of human blood in the spiral groove bearing of a centrifugal blood pump

“…It is possible that optical coherence tomography [ 25 – 27 ] might be able to overcome this limitation, because this technique can produce cross-sectional images such as that shown in Fig. 1 d. Our own group has also employed a hyperspectral imaging system to monitor thrombus formation in the same pump used in this study [ 28 – 31 ]. This system can generate images based on the optical absorption of hemoglobin in the ridge area by acquiring data at multiple wavelengths, such that the hemoglobin concentration over the ridge can be calculated based on the Beer–Lambert law.…”

“…1d. Our own group has also employed a hyperspectral imaging system to monitor thrombus formation in the same pump used in this study [28][29][30][31]. This system can generate images based on the optical absorption of hemoglobin in the ridge area by acquiring data at multiple wavelengths, such that the hemoglobin concentration over the ridge can be calculated based on the Beer-Lambert law.…”

Artificial Organs 2017: A Year in Review

“…Fujiwara et al of the Tokyo Medical and Dental University, Ibaraki, Japan investigated hyperspectral imaging (HIS) for analyzing the thrombus inside a hydrodynamically levitated centrifugal blood pump implanted in pigs. Appearance of an area displaying thrombus was detected within 24 h after the start of the circulation in every experiment.…”