Design and performance testing of an axial-flow ventricular assist device developed at the Fu Wai Hospital in Beijing

Development of ventricular assist devices in China: present status, opportunities and challenges

The growing number of heart failure patients and the scarcity of organ donors account for the huge need for the development of mechanical circulatory systems, including ventricular assist devices (VADs) and artificial hearts, in China. Several research programmes on blood pumps have been under way for the last three decades. However, unlike in other countries, the development of VADs has been extremely slow, and no system is currently approved and available for clinical application. There are many reasons for this situation. This article provides an overview of the present development of experimental and clinical research on VADs in China. In addition, the challenges for the clinical development of mechanical circulatory support in China are discussed.

Short-term in vivo preclinical biocompatibility evaluation of FW-II axial blood pump in a sheep model

We investigated the outcome of FW-II axial pump on healthy sheep (weight, 60-70 kg) for 2 weeks by perioperatively hematological and chemical tests, and circulating activated platelet and leukocyte-platelet aggregates measurements by flow cytometry assays. Complete necropsy and histopathological examinations and thorough pump inspection were performed at study termination for evidence of thrombi. In this experimental series, one sheep died of pulmonary edema, the other four sheep reached the scheduled endpoint of 14 days without device-related problems, and flow range was maintained at 2.5-4.0 L/min. The number of red blood cells and platelets decreased within first 3 days but increased gradually after the first postoperative week. In all animals, serum glutamic oxaloacetic transaminase increased significantly after surgery but gradually returned to normal limits within 2 weeks. Platelet activation, granulocyte-platelet aggregates, and monocyte-platelet aggregates reached the peak at postoperative day 2. Postexplant examinations indicated round thrombus in the hub areas of pumps. No evidence of ischemia or infarction was found in the explanted hearts, livers, spleens, kidneys, and brains of the five animals. Our results demonstrate that FW-II ventricular assist device (VAD) is a promising device for left ventricular (LV) support with moderate anticoagulation.

Intravascular mechanical cavopulmonary assistance for patients with failing Fontan physiology

To provide a viable bridge-to-transplant, bridge-to-recovery, or bridge-to-surgical reconstruction for patients with failing Fontan physiology, we are developing a collapsible, percutaneously inserted, magnetically levitated axial flow blood pump to support the cavopulmonary circulation in adolescent and adult patients. This unique blood pump will augment pressure and thus flow in the inferior vena cava through the lungs and ameliorate the poor hemodynamics associated with the univentricular circulation. Computational fluid dynamics analyses were performed to create the design of the impeller, the protective cage of filaments, and the set of diffuser blades for our axial flow blood pump. These analyses included the generation of pressure-flow characteristics, scalar stress estimations, and blood damage indexes. A quasi-steady analysis of the diffuser rotation was also completed and indicated an optimal diffuser rotational orientation of approximately 12 degrees. The numerical predictions of the pump performance demonstrated a pressure generation of 2-25 mm Hg for 1-7 L/min over 3000-8000 rpm. Scalar stress values were less than 200 Pa, and fluid residence times were found to be within acceptable ranges being less than 0.25 s. The maximum blood damage index was calculated to be 0.068%. These results support the continued design and development of this cavopulmonary assist device, building upon previous numerical work and experimental prototype testing.