Left heart bypass support with the Rotaflow Centrifugal Pump® as a bridge to decision and recovery in an adult

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. Computational fluid dynamics analyses were performed on the flow field inside the pump to estimate the leakage flow through the gap and its impact on the pump efficiency and biocompatibility. The calculations were performed for motor speeds from 3000 to 5000 rpm and flow rates from 1.0 to 9.0 L/min. The leakage flow increased linearly with increasing pressure head of the pump, and the total leakage flow ranged from 2.0 to 27.3% of the total flow. The average wall shear stresses in the casing bottom ranged from 10.6 to 40.9 Pa. The leakage flow of the centrifugal pump with the hydrodynamically levitated impeller had a measurable impact on hydraulic energy losses while enhancing the washout flow to achieve good anti-thrombogenicity.

Acute mechanical circulatory support for cardiogenic shock in India

Cardiogenic shock continues to have high morbidity and mortality, despite advances in the field. Temporary mechanical circulatory support (TMCS) devices, if instituted in a timely fashion, can help stabilize critically ill patients with cardiogenic shock from various aetiologies and cardiac arrest, and provide time for organ recovery or till durable support or transplantation can be achieved. Currently, several options for TMCS devices exist. In this review, we discuss indications, contraindications, characteristics of the various available devices, and important issues pertaining to their management.

A Comprehensive Review of Mechanical Circulatory Support Devices

Treatment strategies to combat cardiogenic shock (CS) have remained stagnant over the past decade. Mortality rates among patients who suffer CS after acute myocardial infarction (AMI) remain high at 50%. Mechanical circulatory support (MCS) devices have evolved as novel treatment strategies to restore systemic perfusion to allow cardiac recovery in the short term, or as durable support devices in refractory heart failure in the long term. Haemodynamic parameters derived from right heart catheterization assist in the selection of an appropriate MCS device and escalation of mechanical support where needed. Evidence favouring the use of one MCS device over another is scant. An intra-aortic balloon pump is the most commonly used short-term MCS device, despite providing only modest haemodynamic support. Impella CP® has been increasingly used for CS in recent times and remains an important focus of research for patients with AMI-CS. Among durable devices, Heartmate® 3 is the most widely used in the USA. Adequately powered randomized controlled trials are needed to compare these MCS devices and to guide the operator for their use in CS. This article provides a brief overview of the types of currently available MCS devices and the indications for their use.

Palladium-Induced Temporal Internalization of MHC Class I Contributes to T Cell-Mediated Antigenicity

Palladium (Pd) is a widely used metal and extremely important biomaterial for the reconstruction of occlusions during dental restorations. However, metallic biomaterials can cause serious allergic reactions, such as Pd-related oral mucositis seen in dentistry. Metal allergy is categorized as a type IV allergy and we demonstrated that CD8 T cells play an important role in Pd allergy previously. As TCR of CD8 T cells recognizes MHC class I/peptide complex, the antigen specificity to this complex seems to be generated during Pd allergy. However, it remains unknown if Pd affects the MHC class I/peptide complex. In this study, we investigated the behavior of the MHC class I/peptide complex in response to Pd treatment. We found that PdCl₂ treatment altered peptide presentation on MHC class I and that co-culture with Pd-treated DC2.4 cells induced activation of Pd-responsive TCR-expressing T cell line. Furthermore, PdCl₂ treatment induced temporal MHC class I internalization and inhibition of membrane movement suppressed Pd-induced T cell-mediated antigenicity. These data suggest that Pd-induced MHC class I internalization is critical for generation of antigenicity through a mechanism including differential peptide loading on MHC class I, which results in Pd allergy.

Transapical ProtekDuo Rapid Deployment Cannula as Temporary Left Ventricular Assist Device in a Jehovah's Witness Patient

Temporary left ventricular support aims to decompress the left ventricle and provide adequate forward flow into the arterial circulation. This can be accomplished with endovascular devices such as the Impella with an internal motor, or with the implementation of cannulae to drain the left ventricle or left atrium and then return to the arterial circulation using an external pump. In this report, the authors describe the transesophageal echocardiography-guided placement of a single-cannula system with the Protek Duo RD (TandemLife, LivaNova) via a left ventricular apical approach to provide minimally invasive left ventricular support in a high-risk Jehovah's Witness patient.

Outcome of Extracorporeal Ventricular Assist Device for Cardiogenic Shock as a Bridge to Transplantation

Background

The extracorporeal ventricular assist device (e-VAD) system is designed for left ventricular support using a permanent life support console. This study aimed to determine the impact of temporary e-VAD implantation bridging on posttransplant outcomes.

Methods

We reviewed the clinical records of 6 patients with the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile 1, awaiting heart transplantation, who were provided with temporary e-VAD from 2018 to 2019. The circuit comprised a single centrifugal pump without an oxygenator. The e-VAD inflow cannula was inserted into the apex of the left ventricle, and the outflow cannula was positioned in the ascending aorta. The median follow-up duration was 8.4±6.9 months.

Results

After e-VAD implantation, lactate dehydrogenase levels significantly decreased, and Sequential Organ Failure Assessment scores significantly improved. Bedside rehabilitation was possible in 5 patients. After a mean e-VAD support duration of 14.5±17.3 days, all patients were successfully bridged to transplantation. After transplantation, 5 patients survived for at least 6 months.

Conclusion

e-VAD may reverse end-organ dysfunction and improve outcomes in INTERMACS I heart transplant patients.

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. We installed this assist system in 9 adult calves (body weight, 90 ± 13 kg): as left ventricular assist device (LVAD) in 6 calves and right ventricular assist device (RVAD) in 3 calves, for over 30 days. Perioperative hemodynamic, hematologic, and blood chemistry measurements were obtained and end-organ effects on necropsy were investigated. All calves survived for over 30 days, with a good general condition. The blood pump was operated at a mean rotational speed and a mean pump flow of 3482 ± 192 rpm and 4.08 ± 0.15 L/min, respectively, for the LVAD and 3902 ± 210 rpm and 4.24 ± 0.3 L/min, respectively, for the RVAD. Major adverse events, including neurological or respiratory complications, bleeding events, and infection were not observed. This novel VAD enabled a long-term support with consistent and satisfactory hemodynamic performance and hemocompatibility in the calf model. The hemodynamic performance, hemocompatibility, and anticoagulative status of this VAD system were reviewed.

Assessment of Safety and Effectiveness of the Extracorporeal Continuous-Flow Ventricular Assist Device (BR16010) Use as a Bridge-to-Decision Therapy for Severe Heart Failure or Refractory Cardiogenic Shock: Study Protocol for Single-Arm Non-randomized, Uncontrolled, and Investigator-Initiated Clinical Trial

BACKGROUND

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. The purpose of this study (NCVC-BTD_01, National Cerebral and Cardiovascular Center-Bridge to Dicision_01) is to assess the safety and effectiveness of the newly developed extracorporeal continuous-flow ventricular assist system employing a disposable centrifugal pump with a hydrodynamically levitated bearing (BR16010) use as a bridge-to-decision therapy for patients with severe heart failure or refractory cardiogenic shock.

METHOD/DESIGN

NCVC-BTD_01 is a single-center, single-arm, open-label, exploratory, medical device, investigator-initiated clinical study. It is conducted at the National Cerebral and Cardiovascular Center in Japan. A total of nine patients will be enrolled in the study. The study was planned using Simon's minimax two-stage phase design. The primary endpoint is a composite of survival free of device-related serious adverse events and complications during device support. For left ventricular assistance, withdrawal of a trial device due to cardiac function recovery or exchange to other ventricular assist devices (VADs) for the purpose of bridge to transplantation (BTT) during 30 days after implantation will be considered study successes. For right ventricular assistance, withdrawal of tal device due to right ventricular function recovery within 30 days after implantation will be considered a study success. Secondary objectives include changes in brain natriuretic peptide levels (7 days after implantation of a trial device and the day of withdrawal of a trial device), period of mechanical ventricular support, changes in left ventricular ejection fraction (7 days after implantation of a trial device and the day of withdrawal of a trial device), and changes in left ventricular diastolic dimension (7 days after implantation of a trial device and the day of withdrawal of a trial device).

ETHICS AND DISSEMINATION

We will disseminate the findings through regional, national, and international conferences and through peer-reviewed journals.

TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN-CTR; R000033243) registered on 8 September 2017.

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. We used three adult goats (body weight, 58-68 kg) to investigate the 30-day performance and hemocompatibility of the newly developed left ventricular assist system, which included the pump, inflow and outflow cannulas, the extracorporeal circuit, and connectors. Hemodynamic, hematologic, and blood chemistry measurements were investigated as well as end-organ effect on necropsy. All goats survived for 30 days in good general condition. The blood pump was operated at a rotational speed of 3000-4500 rpm and a mean pump flow of 3.2 ± 0.6 L min. Excess hemolysis, observed in one goat, was due to the inadequate increase in pump rotational speed in response to drainage insufficiency caused by continuous contact of the inflow cannula tip with the left ventricular septal wall in the early days after surgery. At necropsy, no thrombus was noted in the pump, and no damage caused by mechanical contact was found on the bearing. The newly developed temporary left ventricular assist system using a disposable centrifugal pump with hydrodynamic bearing demonstrated consistent and satisfactory hemodynamic performance and hemocompatibility in the goat model.

Preclinical study of a novel hydrodynamically levitated centrifugal pump for long-term cardiopulmonary support : In vivo performance during percutaneous cardiopulmonary support

An extracorporeal centrifugal blood pump with a hydrodynamically levitated impeller was developed for use in a durable extracorporeal membrane oxygenation (ECMO) system. The present study examined the biocompatibility of the blood pump during long-term use by conducting a series of 30-day chronic animal experiments. The ECMO system was used to produce a percutaneous venoarterial bypass between the venae cavae and carotid artery in adult goats. No anticoagulation or antiplatelet therapy was administered during the experiments. Three out of four animals survived for the scheduled 30-day period, and the blood pumps and membrane oxygenators both exhibited sufficient hydrodynamic performance and good antithrombogenicity, while one animal died of massive bleeding from the outflow cannulation site. The animals' plasma free hemoglobin had returned to within the normal range by 1 week after the surgical intervention, and their hemodynamic and biochemistry parameters remained within their normal ranges throughout the experiment. The explanted centrifugal blood pumps did not display any trace of thrombus formation. Based on the biocompatibility demonstrated in this study, the examined centrifugal blood pump, which includes a hydrodynamically levitated impeller, is suitable for use in durable ECMO systems.

Efficacy of new pediatric extra-corporeal life support system (Endumo 2000) for postoperative management after Norwood operation

This study aimed to assess the efficacy of a new pediatric extra-corporeal life support (ECLS) system (Endumo 2000, Heiwa Bussan, Tokyo, Japan) for postoperative management after the Norwood operation. Thirty-three consecutive patients with hypoplastic left heart syndrome or its variant undergoing the Norwood operation between August 2007 and December 2013 were divided into two groups according to available ECLS devices. Before November 2009, pediatric Emersave (TERUMO, Saitama, Japan) was employed as the ECLS device, and 14 patients were operated on during this period (Emersave era: 7 boys; 2.9 kg). After December 2009, Endumo 2000 was employed and 19 patients were operated on (Endumo era: 8 boys, 3.1 kg). The demographic characteristics of both groups showed no significant differences. ECLS was initiated in 7 of 14 patients (50%) during the Emersave era and 7 of 19 patients (37%) during the Endumo era (p = 0.45). Chest reentry for hemostasis during ECLS support was more frequently needed in patients supported by Emersave (5/7) than Endumo (1/7) (p = 0.03). The first ECLS circuit durability of Endumo was significantly longer than that of Emersave (p = 0.01). The survival at discharge rate in patients required ECLS was 0% (0/7) when supported by Emersave, but 57% (4/7) by Endumo (p = 0.02). As a result, the survival at discharge rate was 43% (6/14) in the Emersave era and 79% (14/19) in the Endumo era (p = 0.03). Longer durability and superior antithrombogenicity of the Endumo 2000 contributed to the improvement of surgical outcomes after the Norwood operation.

Current status of extracorporeal ventricular assist devices in Japan

Extracorporeal VADs are less expensive, their prices reimbursable by the health insurance being about one-sixth of those of implantable VADs in Japan. However, a disadvantage is that, in Japan, their use is restricted to hospitals, necessitating prolonged hospitalization, reducing the patients' quality of life. According to the Japanese registry for Mechanically Assisted Circulatory Support, the survival rate does not differ significantly between patients with extracorporeal and implantable VADs. As in Europe and North America, extracorporeal VADs in Japan are commonly used as Bridge to Decision or Bridge to Recovery. Extracorporeal VADs are switched to implantable VADs as a Bridge-to-Bridge strategy after stabilization or when cardiac function recovery fails. They are also used as right ventricular assist devices (RVADs) in patients with right heart failure. A special characteristic of extracorporeal VADs in Japan is their frequent use as a Bridge to Candidacy. In Japan, indications for implantable VADs are restricted to patients registered for heart transplantation. Therefore, in patients who cannot be registered for transplantation because of transient renal dysfunction, etc., due to heart failure, extracorporeal VADs are used first, and then replaced by implantable VADs after transplant registry is done. Here, we describe the current status of extracorporeal VADs in Japan, focusing on the environmental backgrounds, along with a review of the relevant literature.