Implantable Left Ventricular Assist Device Insertion Techniques

Implantable centrifugal blood pump with dual impeller and double pivot bearing system: electromechanical actuator, prototyping, and anatomical studies

An implantable centrifugal blood pump has been developed with original features for a left ventricular assist device. This pump is part of a multicenter and international study with the objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations and wear evaluation in bearing system were performed followed by prototyping and in vitro tests. In addition, previous blood tests for assessment of normalized index of hemolysis show results of 0.0054±2.46 × 10⁻³ mg/100 L. An electromechanical actuator was tested in order to define the best motor topology and controller configuration. Three different topologies of brushless direct current motor (BLDCM) were analyzed. An electronic driver was tested in different situations, and the BLDCM had its mechanical properties tested in a dynamometer. Prior to evaluation of performance during in vivo animal studies, anatomical studies were necessary to achieve the best configuration and cannulation for left ventricular assistance. The results were considered satisfactory, and the next step is to test the performance of the device in vivo.

Clinical experience with long-term use of implantable left ventricular assist devices: indications, implantation, and outcomes

We describe our clinical experience with 205 implantable left ventricular assist devices at the Cleveland Clinic between December 1991 and January 2000, along with manufacturers' data submitted to the Food and Drug Administration. In patients with end-stage cardiac failure who are suitable candidates for transplantation, these devices serve as excellent bridges to transplantation. Recent modifications have increased pump reliability and reduced thromboembolic rates. The vented electric HeartMate (Thermocardiosystems Inc, Woburn, MA) and the Novacor (Baxter-Novacor, Oakland, CA) left ventricular assist systems allow patients to be discharged from the hospital while awaiting a donor heart. Experience with long-term support is providing insights into permanent implantation of these devices as destination therapy. Although infection remains a major impediment to long-term support, patient-pump interactions leading to changes in the coagulation and immune systems are being recognized, and these interactions may have important implications with respect to thromboembolism, infection, and sensitization to human leukocyte antigens (HLAs). Better understanding of these factors may eventually lead to the development of permanently implantable pumps as an alternative to transplantation.

Clinically available intracorporeal left ventricular assist devices

There are now 3 commercially approved intracorporeal left ventricular assist devices (LVADs). Product similarities include (1) LV apex, to pump, to ascending aorta flow patterns, (2) excellent hemodynamic support with reversal of heart failure and neurohormone/cytokine milieu, and (3) the requirement of major surgery for device implantation and later explantation, with or without transplant. Two electrically powered models allow a tether-free existence and hospital discharge. All complications are being addressed, and in the past decade, device failure and thromboemboli have been reduced. Infection continues to be an obstacle to more widespread adoption of therapy. Despite pre-LVAD shock, most patients (65% to 78% by Food and Drug Administration data) survive until transplant (averaging 80 to 96 days of LVAD support), and posttransplant survival is equal to nonbridged patients. As the problem of infection is reduced, more widespread LVAD use can be anticipated.