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The Journal of Heart and Lung Transplantation
International Society for Heart and Lung Transplantation.

First implantation in man of a new magnetically levitated left ventricular assist device (HeartMate III)

      Outcomes of heart failure patients supported by a continuous-flow left ventricular assist device (LVAD) have steadily improved during the past decade, largely due to better patient selection and management.
      • John R.
      • Naka Y.
      • Smedira N.G.
      • et al.
      Continuous flow left ventricular assist device outcomes in commercial use compared with the prior clinical trial.
      • Jorde U.P.
      • Kushwaha S.S.
      • Tatooles A.J.
      • et al.
      Results of the destination therapy post-Food and Drug Administration-approval study with a continuous flow left ventricular assist device: a prospective study using the INTERMACS registry (Interagency Registry for Mechanically Assisted Circulatory Support).
      Nevertheless, adverse events, such as bleeding, infection, stroke, and thrombus, persist and limit the overall effectiveness of this therapy. Bleeding is the most common serious adverse event that results from the extensive surgery required for implantation and blood component damage due to shear forces in the small blood flow paths of current design axial-flow and centrifugal-flow pumps. Excessive bleeding results in reoperations, intensive care time, and total hospital stay, which greatly increases a patient’s exposure for infection. The current clinically used pumps create levels of shear force that can activate platelets and damage von Willebrand factor, causing a disruption in the coagulation system that can manifest as thrombosis or gastrointestinal bleeding.
      The HeartMate III LVAD (Thoratec Corp, Pleasanton, CA) is a new compact intrapericardial centrifugal-flow pump with a full magnetically levitated rotor (Figure 1). The design differs from currently used devices due to actively controlled rotation and levitation of the rotor allowing gaps in the blood flow that are 10 to 20 times wider, which may minimize blood component trauma and result in more stable coagulation. The HeartMate III is now under clinical investigation, and we present here a case report of the first implantation of the device to support a patient with severe heart failure.
      Figure thumbnail gr1
      Figure 1The Heart Mate III left ventricular assist device blood pump with the full magnetically levitated rotor allows large pump gaps. Blood flow is received from the left ventricle and is pumped through a graft attached to the ascending aorta.
      The patient is a 55-year-old man with the diagnosis of dilated cardiomyopathy and a recent history of multiple hospital admissions due to worsening heart failure symptoms. With multiple medications, the mean arterial blood pressure was 70 mm Hg, cardiac index was 2.1 liters/min/m2, and the left ventricular ejection fraction was 10% to 15%. He was classified as Interagency Registry for Mechanically Assisted Circulatory Support Profile 3. After meeting the HeartMate III Conformité Européene Mark Study inclusion criteria, the patient gave informed consent, and the implantation was performed by Dr. Schmitto and his team at Hannover Medical School, Hanover, Germany on June 25, 2014.
      After a median sternotomy, the pericardium was only partially opened to help protect right heart function yet allowing access to the vena cava and aorta for cardiopulmonary bypass cannulation. Once full cardiopulmonary bypass was started, the pericardium was fully opened, the heart was elevated, and the myocardium was cored with the HeartMate coring knife approximately 1 cm medial to the left ventricular apex. The sewing cuff was attached around the apical opening with 2-0 Ethibond pledgeted sutures. The inflow conduit was inserted into the left ventricle, and the device was quickly secured to the heart with a locking mechanism. The outflow graft was trimmed for length and anastomosed to the ascending aorta. The percutaneous lead (driveline) was externalized with a double-tunnel technique and exited through the right upper quadrant of the abdominal wall. Cardiopulmonary bypass lasted 59 minutes, and the total operative time was 149 minutes.
      The patient tolerated the procedure well, with minimal blood loss and no other complications, and was transported to the cardiac intensive care unit in stable condition. A postoperative chest X-ray image shows the position of the device in the chest (Figure 2).
      Figure thumbnail gr2
      Figure 2A postoperative chest X-ray image shows the position of the Heart Mate III left ventricular assist device at the apex of the left ventricle and the percutaneous lead traversing along the diaphragm to the right upper quadrant of the abdomen.
      Immediately postoperatively, intravenous heparin was administered as a bridge until anticoagulation with phenprocoumon was in the therapeutic range, with a target international normalized ratio of 2.0 to 3.0, plus aspirin at 100 mg/day. The patient experienced a seizure episode that was treated with midazolam, and a thoracentesis was required on Post-operative Day 14. The total hospital stay was 19 days. Two readmissions were required because of multiple implantable cardioverter-defibrillator firings during exercise and an anticoagulation adjustment because the international normalized ratio was out of range. Table 1 lists the patient’s vital signs, laboratory data, and echocardiogram results from pre-implant to Month 6 of support. The patient remains at home 9 months after implantation with New York Heart Association Functional Class I symptoms and exercises regularly.
      Table 1Patient’s Vital Signs, Laboratory, and Echocardiogram Data
      VariablesPre-implantWeek 1DischargeMonth 1Month 6
      Vital signs
       Respiratory rate, breaths/min1826211618
       Heart rate, beats/min4889909468
       Blood pressure mean, mm Hg70103
       Doppler blood pressure, mm HgNA8790102
      Pump parameters
       Pump flow, liters/minNA3.73.84.44.3
       Pump speed, rpmNA5,2005,4005,3005,300
       Pulsatility indexNA5.46.83.74
       Power, WNA3.8444
      Laboratory data
       Lymphocytes, %23.923.723.622.630.6
       Platelets, ×1,000/ml172190301332217
       White blood cells, ×1,000/ml6.810.810.712.310.1
       Hemoglobin, g/dl14.111.511.611.515.1
       International normalized ratio1.051.212.242.822.55
       Lactate dehydrogenase, U/liter260276200222252
       AST, U/liter2416141523
       ALT, U/liter239121316
       Total bilirubin, μmol/liter95459
       BUN, mmol/liter8.22.6455.7
       Creatinine, μmol/liter12980788097
       Uric acid, μmol/liter486402251312448
       Sodium, mmol/liter138141135139141
       Potassium, mmol/liter4.64.54.54.23.9
       Total protein, g/liter7259677075
       Albumin, g/liter3827273237
      Echocardiogram
       Left ventricular
        Ejection fraction, %20NANA3525
        Systolic dimension, mm81NANA67NA
        Diastolic dimension, mm907471
       Aortic valve openNANANAYesNo
       Mitral regurgitationMildMildNone
      ALT, alanine aminotransferase; AST, aspartate aminotransferase; BUN, blood urea nitrogen; NA, not applicable/available.
      The unique feature of the HeartMate III is its full magnetically levitated rotor (Figure 1), which eliminates the need for mechanical bearings or hydrodynamic blood bearings. The shear forces characteristic of current continuous-flow LVADs are known to potentially damage red blood cells and von Willebrand factor and to activate platelets. These effects can result in hematologic complications such as hemorrhagic and ischemic stroke, gastrointestinal bleeding, and pump thrombosis.
      • Mehra M.R.
      • Stewart G.C.
      • Uber P.A.
      The vexing problem of thrombosis in long-term mechanical circulatory support.
      • Schmitto J.D.
      • Avsar M.
      • Haverich A.
      Increase in left ventricular assist device thrombosis.
      • Stulak J.M.
      • Lee D.
      • Haft J.W.
      • et al.
      Gastrointestinal bleeding and subsequent risk of thromboembolic events during support with a left ventricular assist device.
      There are large secondary flow path gaps of 0.5 mm along the side of the rotor, and 1.0 mm above and below the rotor, which are 10 to 20 times that of other devices being used. The gaps are consistently large at all rotational speeds due to active control of the magnetically levitated rotor designed to reduce potential areas of stasis and minimize shear stress. The blood-contacting surfaces are textured with sintered titanium microspheres designed to allow the development of a pseudoneointima
      • Rose E.A.
      • Levin H.R.
      • Oz M.C.
      • et al.
      Artificial circulatory support with textured interior surfaces. A counterintuitive approach to minimizing thromboembolism.
      as a biologic barrier between the artificial material and the blood to minimize thrombosis.
      The small size of the pump and its positioning within the pericardial space eliminates the need for an abdominal pump pocket. Less surgical trauma and associated bleeding should shorten recovery time and reduce the occurrence of infection complications that often occur as a result of blood transfusions and prolonged intensive care. The magnetically levitated pump rotor is frictionless, eliminating heat generation and wear of mechanical components. The control system also creates an artificial pulse by alternating the pump rotor speed 30 times per minute to increase pulsatile flow, with potential benefits including regular washing of flow pathways within the pump. The driveline has a modular design that allows replacement of the external portion in case of damage.
      This first-in-man implantation of the HeartMate III magnetically levitated LVAD initiated the Conformité Européene Mark clinical trial, which now has enrolled 50 patients with end-stage heart failure in Germany, Czech Republic, Kazakhstan, Austria, Australia, and Canada, including 8 patients at our institution. Enrollment in the trial was completed on November 27, 2014, with the 6-month follow-up in progress. The HeartMate III United States clinical trial was initiated in September 2014 and is also ongoing.

      Disclosure statement

      Hannover Medical School receives grant funding from Thoratec Corp. JDS as well as MA are consultants for Thoratec Corp.

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