Implantation of ventricular assist devices (VADs) has become an indispensable alternative for the treatment of patients with severe end-stage heart failure [1‐3]. However, despite recent advancements in the field of VADs, the outcome remains poor for patients classified as interagency registry for mechanically assisted circulatory support (INTERMACS) profile 1 especially with severe respiratory, renal, and hepatic failure [4]. Patients with serious low cardiac output syndrome require an adequate amount of blood flow to recover from severe multi-organ failure. The use of temporary devices such as extracorporeal VAD provides a solution to establish adequate blood flow and stabilize the hemodynamic state of the patients while further assessment of the clinical condition is being performed and a process referred to as bridge to decision (BTD), when it is unclear whether the patient’s heart will recover or whether the patient will need alternative, longer-term therapy or transplantation [5‐8]. In terms of cost-effectiveness, an extracorporeal continuous-flow VAD that uses a disposable pump is desirable for BTD [9]. Recently, some clinicians have reported using a conventional disposable centrifugal pump and a cannula for cardiopulmonary bypass (CPB) for BTD [10, 11]. However, in conventional pumps with contact bearings, thrombus formation occurs within just a few days because of blood cell destruction and blood coagulation caused by mechanical wear and heat generation. A blood pump system with longer durability and superior hemocompatibility than conventional pump for cardiopulmonary bypass, and lower cost than implantable VADs is required that is able to provide enough time for decision-making without the risk of system replacement or system-related complications. Recent developments in the field of blood pumps have focused on noncontact bearing systems with hydrodynamically or magnetically levitated bearings, which have demonstrated excellent blood compatibility and low hemolytic effect, ensuring long-term durability of the VADs [12‐15]. As regards an implantable left VAD (LVAD), HeartMate 3 LVAD was invented as a fully magnetically levitated centrifugal-flow chronic LVAD and Netuka et al. [15] showed that HeartMate 3 was safe, with high 30-day and 6-month survival rates, a favorable adverse event profile, and improved quality of life and functional status. The prospective, randomized Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy with HeartMate 3 (MOMENTUM 3) clinical trial has been carried out to evaluate the safety and effectiveness of the HeartMate 3 LVAD by demonstrating non-inferiority to the HeartMate II LVAD (also St. Jude Medical, Inc.) [16].

As regards extracorporeal VAD, there is no approved centrifugal-flow pump for LVAD use in the world. The Levitronix® CentriMag® ventricular assist system (VAS) (Levitronix LLC; Waltham, MA) is a magnetically levitated centrifugal-flow pump that can be clinically applied as LVAD and right VAD (RVAD) in USA [6, 8]. Although the Levitronix CentriMag is authorized by federal law to provide temporary circulatory support for up to 30 days for patients in cardiogenic shock due to acute right ventricular failure, the effectiveness of this device for this use has not been demonstrated and distribution of this device is restricted to use by or on the order of a physician. When used for left or biventricular support for periods over 6 h, the CentriMag VAS is an investigational device limited by federal (USA) law to investigational use. This device will be used for up to 30 days to support one or both sides of the heart as a bridge to decision, when it is unclear whether the patient’s heart will recover or whether the patient will need alternative, longer-term therapy or transplantation. This prospective, non-randomized trial will enroll a total of 30 patients at up to 25 clinical centers. The CentriMag Pivotal Trial will be conducted jointly by Thoratec and Levitronix.

The core components of the CentriMag VAS consist of a continuous-flow centrifugal blood pump, a primary console and motor, a flow probe, a backup console and motor, a tubing, and cannulas. The pump, which has a priming volume of 31 mL, can be operated up to a maximum speed of 5500 rpm while generating up to 9.9 L/min flow [17]. When the pump is inserted into the motor and activated, the internal impeller is electromagnetically levitated and centered, eliminating the need for shafts, seals, and bearings in the pump. Shafts, seals, and bearings are the sites typically responsible for hemolysis, thrombus, and particle formation. Large gaps between the impeller and the pump housing are designed to minimize potential shear forces on blood cells, thereby allowing high blood flow rate with minimal hemolysis. Utilizing magnetic levitation to suspend and spin the impeller reduces friction in the pump and eliminates the point source of friction (bearing) resulting in minimal heat and wear of the pump components.

Our center developed a new extracorporeal continuous-flow temporary LVAD that uses a novel disposable centrifugal blood pump with a hydrodynamically levitated bearing (HLB). As ensuring the performance and safety of the VAD as a whole is important, the combination of the pump, cannulas, connectors, and circuits was well designed. An HLB utilizes hydrodynamic pressure at the small gaps between the rotating part (the impeller) and the stationary part (the casing wall) to counter mechanical loads, and this pressure, in a general sense, is dependent on the rotational speed (RS). There remains a possibility of mechanical contact between the rotating part and the stationary part when the blood pump is operated at a low speed. The effectiveness and safety of the pump in the setting of extracorporeal membrane oxygenation have been reported [18], in which the afterload of the blood pump is assumed to be higher than that in LVAD cases because of small cannula diameters and the hydraulic resistance of oxygenators. In the goat model, this newly developed temporary LVAD demonstrated consistent and satisfactory hemodynamic performance and hemocompatibility over the course of a 30-day experiment [19]. The outcomes of this previous study have served to establish the optimal composition and design of our new LVAD for BTD and this newly developed LVAD represents a promising tool for BTD in critically ill patients.

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 extracorporeal continuous-flow VAD (BR16010) use as a bridge-to-decision therapy for patients with severe heart failure or refractory cardiogenic shock.

Inclusion and exclusion criteria are shown in Table 1. Patients with severe heart failure or refractory cardiogenic shock refractory to optimal medical management, standard surgical procedures, or mechanical circulatory supports (e.g., IABP, VA bypass, and PCPS) are candidates for the study. All patients are required to provide written informed consent. Considering that BTD is a medical emergency, written informed consent of the patient’s next of kin is accepted in patients who are unconscious by therapeutic reason. Patients are notified at enrollment of their freedom to abandon the study at any time without consequences.

The trial VAD is implanted within 3 days after study entry. Patients were followed to the primary endpoint at 30 days after implantation of trial VAD or other outcomes (transplant, explant, or death), whichever occurred first. Patients will be followed for 7 days after removal or until other outcomes. For enhancing patient safety, the enrollment is held after the fourth patient is registered until the independent safety board confirms the 7-day safety for the patients. A summary of the study design is shown in Fig. 3. The schedule of data to be collected is presented in Table 2.