Progress of extracorporeal centrifugal pumps for mechanical circulatory supports.

This review traces the evolution of centrifugal blood pumps in mechanical circulatory support (MCS) systems. Initially met with concerns over blood damage and thrombus formation, centrifugal pumps have become crucial components in ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) due to their simplified drive mechanisms and adaptability. This paper outlines three generations of centrifugal pump development: first-generation pumps with sealing components, second-generation pumps utilizing pivot bearings, and third-generation pumps employing contactless bearings.

Feasibility of an animal model for long-term mechanical circulatory support with Impella 5.5 implanted through carotid artery access in sheep.

Impella is a mechanical circulatory support device of a catheter-based intravascular microaxial pump for left ventricular support and unloading. However, nonclinical studies assessing the effects of the extended duration of left ventricular unloading on cardiac recovery are lacking. An animal model using Impella implanted with a less invasive procedure to enable long-term support is required.

Hemodynamic Evaluation of Asynchronous Speed Modulation of a Continuous-Flow Left Ventricular Assist Device in an Acute-Myocardial Injury Sheep Model.

Asynchronous rotational-speed modulation of a continuous-flow left ventricular assist device (LVAD) can increase pulsatility; however, the feasibility of hemodynamic modification by asynchronous modulation of an LVAD has not been sufficiently verified. We evaluated the acute effect of an asynchronous-modulation mode under LVAD support and the accumulated effect of 6 consecutive hours of driving by the asynchronous-modulation mode on hemodynamics, including both ventricles, in a coronary microembolization-induced acute-myocardial injury sheep model. We evaluated 5-min LVAD-support hemodynamics, including biventricular parameters, by switching modes from constant-speed to asynchronous-modulation in the same animals ("acute-effect evaluation under LVAD support").

Feasibility study of an artificial placenta system consisting of a loop circuit configuration extracorporeal membrane oxygenation with a bridge circuit in the form of the umbilical arterial-venous connection.

We developed a new artificial placenta (AP) system consisting of a loop circuit configuration extracorporeal membrane oxygenation (ECMO) with a bridge circuit designed to be applied to the fetus in the form of an umbilical arterial-venous connection. We aimed to evaluate the feasibility of the AP system by performing a hydrodynamic simulation using a mechanical mock circulation system and fetal animal experiment. The effect of the working condition of the AP system on the fetal hemodynamics was evaluated by hydrodynamic simulation using a mechanical mock circulation system, assuming the weight of the fetus to be 2 kg.

Coronary microembolization sheep model by adjusting the number of microspheres based on coronary blood flow.

Background: A heart failure (HF) model using coronary microembolization in large animals is indispensable for medical research. However, the heterogeneity of myocardial response to microembolization is a limitation. We hypothesized that adjusting the number of injected microspheres according to coronary blood flow could stabilize the severity of HF.

Numerical simulation of the leakage flow of the hydrodynamically levitated centrifugal blood pump for extracorporeal mechanical circulatory support systems.

Extracorporeal centrifugal pumps are widely used in various forms of mechanical circulatory support, including extracorporeal membrane oxygenation and ventricular assist device. A durable centrifugal pump was developed by implementing a new hydrodynamic bearing design that prevents the impeller from touching to the casing wall and provides sufficient washout through the pump to prevent thrombus formation in the pump. The hydrodynamic bearings of the pump are composed of dual annular paths located on both sides of the impeller.

Assessment of ocular blood flow in continuous-flow ventricular assist device by laser speckle flowgraphy.

Although the influence of continuous-flow left ventricular assist device (CF-LVAD) support on peripheral circulation has been widely discussed, its monitoring modalities are limited. The aim of this study was to assess the peripheral circulation using the laser speckle flowgraph (LSFG) which can quantitatively measure the ocular blood flow. We implanted a centrifugal CF-LVAD (EVAHEART; Sun Medical Technology Research Corporation, Nagano, Japan) in five adult goats (body weight 44.

Evaluation of cardiac beat synchronization control for a rotary blood pump on valvular regurgitation with a mathematical model.

We have studied the cardiac beat synchronization (CBS) control for a rotary blood pump (RBP) and revealed that it can promote pulsatility and reduce cardiac load. Besides, patients with LVAD support sometimes suffer from aortic and mitral regurgitation (AR and MR). A control method for the RBP should be validated in wider range of conditions to clarify its benefits and pitfalls prior to clinical application.

Preclinical biocompatibility study of ultra-compact durable ECMO system in chronic animal experiments for 2 weeks.

Although the innovation has come in ECMO field, many problems remain unresolved. One of the main problems is about long-term durability and biocompatibility. Another is the system's size, weight, and its complicated equipment.

A Novel Extracorporeal Continuous-Flow Ventricular Assist System for Patients With Advanced Heart Failure - Initial Clinical Experience.

Background: Bridge-to-decision (BTD) devices providing temporary mechanical circulatory support should be introduced to patients with advanced heart failure. This study evaluated the effectiveness and safety of a BTD device comprising an innovative extracorporeal continuous-flow temporary ventricular assist device (VAD) driven by a novel hydrodynamically levitated centrifugal flow blood pump.

Methods and results: Nine patients, comprising 3 with dilated cardiomyopathy, 3 with fulminant myocarditis, and 3 with ischemic heart disease, and 6 males, whose mean age was 47.

Mathematical evaluation of cardiac beat synchronization control used for a rotary blood pump.

We studied a control method of rotary blood pumps (RBPs), which is called as the cardiac beat synchronization (CBS) system. Usually, RBPs operate at constant target rotational speed, meanwhile, the CBS system modulates target speed synchronizing with cardiac beat. We built a computer simulation method to evaluate the CBS system.

Interventricular dyssynchrony during continuous-flow left ventricular assist device support: observation using the conductance method.

The purpose of this study was to observe and clarify the interventricular dysscynchrony caused by continuous-flow left ventricular assist device (CF-LVAD) support using the conductance method. During CF-LVAD support, the systolic phase of the left ventricle (LV) becomes shorter than that of the right ventricle (RV). Accordingly, timing of the systole and diastole during the cardiac cycle is not synchronous between the LV and RV.

Quantification of interventricular dyssynchrony during continuous-flow left ventricular assist device support.

Under continuous-flow left ventricular assist device (CF-LVAD) support, the ventricular volume change and cardiac cycle between the left ventricle (LV) and right ventricle (RV) become dyssynchronous due to the shortening of the LV systole. The purpose of this study was to quantify interventricular dyssynchrony based on different CF-LVAD support conditions and assess its relationship with LV unloading. In this study, we evaluated seven goats (body weight 44.

Miniaturized centrifugal ventricular assist device for bridge to decision: Preclinical chronic study in a bovine model.

We developed a novel miniaturized extracorporeal centrifugal pump "BIOFLOAT NCVC (Nipro Corporation Osaka, Japan) as a ventricular assist device (VAD) and performed a preclinical study that is part of the process for its approval as a bridge to decision by the pharmaceutical and medical device agencies. The aim of this study was to assess the postoperative performance, hemocompatibility, and anticoagulative status during an extended period of its use. A VAD system, consisting of a hydrodynamically levitated pump, measuring 64 mm by 131 mm in size and weighing 635 g, was used.

Three-dimensional simulation for left ventricular assist device implantation in a small patient with chest wall deformity.

The rate of patients requiring left ventricular assist device (LVAD) implantation remains at a pace exceeding 2000 per year worldwide. Children and small adult patients, with a body surface area <1.5 m2, are at a disadvantage for receiving an implantable LVAD because of its large pump size.

Accurate Method of Quantification of Aortic Insufficiency During Left Ventricular Assist Device Support by Thermodilution Analysis: Proof of Concept and Validation by a Mock Circulatory System.

Aortic insufficiency (AI) is an intractable complication during long term left ventricular assist device (LVAD) support. Conventional evaluation of AI depends on ultrasound evaluation, which is mainly a qualitative, not a quantitative method. The pathophysiology of AI during LVAD is shunt formation.

The angle of the outflow graft to the aorta can affect recirculation due to aortic insufficiency under left ventricular assist device support.

Aortic insufficiency (AI) is a crucial complication during continuous-flow left ventricular assist device (LVAD) support. Our previous clinical study suggested that a larger angle between the outflow graft and the aorta (O-A angle) could cause AI progression. This study examined the effect of the O-A angle on the hemodynamics of AI under LVAD support in an acute animal experimental model.

Evaluation of the Novel Centrifugal Pump, CAPIOX SL, in Chronic Large Animal Experiments.

In the development of a new device for extracorporeal circulation, long-term durability and biocompatibility are required. The CAPIOX SL Pump (SL pump, Terumo Corporation, Tokyo, Japan), which is a centrifugal pump using a two-pivot bearing, was developed with the hope of suppressing pump thrombus formation around the bearings. This study aimed to evaluate the in vivo performance of the SL pump in the condition assumed severe clinical situation for long-term extracorporeal membrane oxygenation (ECMO) support.

Preclinical animal study of the NIPRO-ventricular assist device for use in pediatric patients.

Although the outcomes of patients with end-stage heart failure treated with implantable left ventricular assist devices have improved, extracorporeal left ventricular assist devices continue to play an important role, especially in pediatric patients. The present study aimed to examine the long-term biocompatibility of a small-sized extracorporeal pneumatic left ventricular assist device (NIPRO-LVAD) used in a 30- to 90-day animal experiment. The NIPRO-LVAD was designed for pediatric patients or small-sized adults.

Differences in clotting parameters between species for preclinical large animal studies of cardiovascular devices.

Several species of domestic animals are used in preclinical studies evaluating the safety and feasibility of medical devices; however, the relevance of animal models to human health is often not clear. The purpose of this study was to compare the clotting parameters of animal models to determine which animals most adequately mimic human clotting parameters. The clotting parameters of the different species were assessed in whole blood by in vitro thromboelastography using the clotting activators, such as tissue factor (extrinsic clotting screening test, EXTEM) and partial thromboplastin phospholipid (intrinsic clotting screening test, IINTEM).

Novel temporary left ventricular assist system with hydrodynamically levitated bearing pump for bridge to decision: initial preclinical assessment in a goat model.

The management of heart failure patients presenting in a moribund state remains challenging, despite significant advances in the field of ventricular assist systems. Bridge to decision involves using temporary devices to stabilize the hemodynamic state of such patients while further assessment is performed and a decision can be made regarding patient management. We developed a new temporary left ventricular assist system employing a disposable centrifugal pump with a hydrodynamically levitated bearing.