LVADS

covers all generation left ventricular assist devices

1. LEFT VENTRICULAR ASSIST DEVICES

2. INDICATIONS Bridge to cardiac transplantation  Bridge to decision  As destination (or permanent) therapy, As a bridge to recovery of heart function.

3. Bridge to transplantation LVADs are inserted into patients who have worsening New York Heart Association (NYHA) Class III or IV HF often despite inotropic plus intra-aortic balloon pump support LVADs life-saving in these deteriorating patients who might otherwise die before a donor heart becomes available, but they can also improve secondary organ function prior to transplantation, reduce pulmonary hypertension, and enable improvement in nutritional status, all of which are associated with improved post-transplant survival.

4. Bridge to decision Many patients receive an LVAD before a final decision regarding transplantation eligibility has been able to be reached (use of which has been termed "bridge to decision" or BTD). 

5. Destination therapy As survival rates with LVAD support have improved, the use of these devices as permanent (rather than "bridge" therapy) has evolved and expanded considerably . DT refers to this long-term use of LVADs as an alternative to transplantation in patients with end-stage HF who are considered to be ineligible for transplantation

6. Bridge to recovery There is now evidence that LVAD unloading can promote recovery of myocardial function The strategy of device implantation to promote recovery of myocardial function is known as "bridge to recovery." Usually, however, the device is not implanted specifically as a "bridge to recovery" but as DT or BTT and then if sufficient myocardial recovery has been deemed to have occurred on testing of the underlying cardiac function explantation of the pump considered.

7. Destination Therapy vs. Bridge to Transplantation Long-term placement Destination Therapy (DT) Not a heart transplant candidate NYHA IV LVEF <25% Maximized medical therapy >45 of 60 days; IABP for 7 days; OR 14 days Functional limitation with a peak oxygen consumption of less than or equal to 14 ml/kg/min Life expectancy < 2 years Bridge to Transplantation (BTT) Patient is approved and currently listed for transplant NYHA IV Failed maximized medical therapy

8. Things to Consider Before Placing ANY type of VAD Support Are there any contraindications to VAD support? End-stage lung, liver, or renal disease Metastatic disease Medical non-adherence or active drug addiction Active infectious disease Inability to tolerate systemic anticoagulation (recent CVA, GI bleed, etc.,) Moderate to severe RV dysfunction for some LVADs What are our other issues in this particular patient? What are the patient’s goals? What are our goals? What happens if we don’t meet our goals?

9. INTERMACS SCORE Interagency Registry for Mechanically Assisted Circulatory Support Long-Term LVAD Ideal candidates are INTERMACS classes 3-4 Short-Term LVAD Candidates are INTERMACS classes 1-2 Not a LVAD Candidate INTERMACS 1 or those with multisystem organ failure

10. DEVICE FIRST GENERATION DEVICES pulsatile positive displacement pumps HeartMate I device Thoratec paracorporeal ventricular assist device   Novacor

11. HeartMate I device The HeartMate I (HM I) was inserted in over 5000 patients REMATCH trial It has a pusher-plate actuator that is powered pneumatically or electrically. A cannula is placed in the apex of the left ventricle and blood flows through a Dacron conduit through a porcine valve to the pump and is returned into a Dacron outflow graft through another porcine valve inserted in the ascending aorta. The HeartMate I contains a unique blood pumping surface consisting of titanium microspheres and a fibrillar textured inner surface that promoted the formation of a " pseudointima " that resists thrombogenesis . Thus, the only antithrombotic therapy needed was aspirin

12. The HeartMate I underwent several design improvements and evolved from the pneumatic to the vented electric (VE) to the XVE

13. Thoratec paracorporeal ventricular assist device The Thoratec paracorporeal ventricular assist device (PVAD) has been inserted in over 3000 patients. It has the advantage that it can be used as an LVAD, RVAD, or two together as a BIVAD Alternating positive and negative air pressure generated by a console or portable pneumatic driver produces a beat rate of 40 to 110 bpm and a flow rate of 1.3 to 7.2 L/min

14. The PVAD is positioned outside the body ( paracorporeal ) on the anterior abdominal wall with cannulas crossing into the chest wall. Patients supported by this pump require warfarin (goal INR 2.5 to 3.5) plus aspirin therapy.

15. Novacor   The Novacor LVAD was implanted in over 1600 patients for durations of up to 6.1 years, but has been discontinued after trials showing a high rate of stroke.

16. SECOND GENERATION DEVICES Continuous flow devices, including the second generation devices (axial flow pumps)  Continuous flow pumps account for 100 percent of patients receiving DT since 2010 and more than 95 percent of patients receiving primary MCS implants  HeartMate II   Jarvik 2000 Berlin Heart INCOR

17. HeartMate II   Continuous flow axial blood pump with an internal rotor with helical blades that curve around a central shaft The pump weighs 350 g and it is approximately 7 cm in length and 4 cm at its largest diameter. It can generate up to 10 L/min of flow at a pressure of 100 mmH

18. The axial flow design and absence of blood sac eliminates the need for venting of pulsatile volume (required for the first generation of implantable pumps), thus reducing the size of the percutaneous drive lead and also eliminating the need for internal one-way valves. Blood flows through an inflow cannula from the apex of the LV to the pump and returns back through an outflow cannula to the ascending aorta.

19. Jarvik 2000 Continuous flow axial blood pump that has an intraventricular position, with the whole pump sitting within the LV cavity The pump weighs 85 g, measures 2.4 cm in diameter, and is 5.5 cm long. The pump can generate up to a maximum of 7 L/min of flow.

20. The single moving component is the impeller located in the center of the titanium housing. A brushless direct-current motor, contained within the housing, creates the electromagnetic force necessary to rotate the impeller. Blood flow is directed through the outlet graft by stator blades located near the pump outlet and it returns to either the ascending or descending aorta

21. Berlin Heart INCOR   Continuous flow axial flow pump marketed in Europe but not in the US. Blood passes into the INCOR it first passes an inducer that directs laminar flow onto the impeller, which is suspended by a magnetic bearing and floats free of contact with other parts. The impeller operates at speeds between 5000 and 10,000 rotations per minute. Blood is then directed to a stationary diffuser that has specially aligned blades that reduce the rotational effect of the blood flow and thus builds additional pressure which assists in the transport of blood through the outflow cannula to the aorta.

22. THIRD GENERATION PUMPS centrifugal pumps that have been designed for their long durability, compact size, optimization of blood flow through the device to minimize the risk of thrombus formation and hemolysis , and simplified surgical implantation. HeartWare HeartMate 3

23. HeartWare Continuous flow centrifugal third generation pump  It was approved by the FDA as a bridge to transplantation in November 2012 and as destination therapy in September 2017. HeartWare has only one moving part, the impeller, and no mechanical bearings.  Because the HeartWare pump has no bearings and runs at lower rpm, it is likely to have long durability. It is much smaller than earlier devices and easier to surgically implant

24. The pump weighs 140 g and has an external diameter of 53 mm. The impeller spins at rates between 1800 and 4000 rpm and generates up to 10 L/min of blood flow. Implantable directly adjacent to the heart in the pericardial space due to its small total size, equivalent to 50 cc The impeller is suspended within the pump housing through a combination of passive magnets and a hydrodynamic thrust bearing.  This hydrodynamic suspension is achieved by a gentle incline on the upper surfaces of the impeller blades. When the impeller spins, blood flows across these inclined surfaces, creating a "cushion" between the impeller and the pump housing. The inflow cannula is integrated with the device itself, ensuring proximity between the heart and the pumping mechanism which facilitates implantation and ensures optimal blood flow characteristics.  The impeller has a wide blade to help minimize risk of pump induced hemolysis or thrombus.

25. HeartMate 3   The HeartMate 3 is a fully magnetically levitated centrifugal-flow device that is inserted into the apex of the left ventricle The rotor spins at rates of 3000 to 9000 rpm and generates up to 10 L/min of blood flow. The mass of the HeartMate 3 is 475 g, including the motor (535 g), the inflow cannula, recovery section, outflow graft, bend relief, and all connecting hardware.   it incorporates rapid changes in rotor speed to create an intrinsic artificial pump pulse (asynchronous with the native heart beat) to reduce stasis in the pump

26. BIVENTRICULAR SUPPORT Total artificial heart A pulsatile total artificial heart that continues to be used clinically in over 50 centers worldwide The SynCardia TAH is the only TAH system to receive FDA, CE, and Canadian Health approval for clinical implantation The size of the artificial heart has restricted its use to patients with a large enough body habitus to accommodate positioning within the thoracic cavity.  To be eligible for use of the SynCardia TAH, the patients must have a body-surface area of >1.7 or a distance of ≥10 cm from the 10 th  anterior vertebral body to the inner table of the sternum on computed tomographic scanning (CT).

27. The SynCardia TAH weighs 160 g and consists of two artificial ventricles, each made of semi-rigid polyurethane housing with four flexible polyurethane diaphragms separating the blood chambers from the air chambers The diaphragms enable the artificial ventricle to fill and then eject blood when compressed by air from the external console. Mechanical valves, mounted in the inflow (27 mm) and outflow (25 mm) ports of each artificial ventricle, control the direction of blood flow. The maximum dynamic stroke volume of each ventricle is 70 mL, which enables generation of a flow rate up to 9.5 L per minute. Each artificial ventricle driveline conduit is tunneled through the chest wall. The right and left artificial ventricles are attached to seven-foot pneumatic drivelines that connect to the back of the external console.

28. The external console weighs 180 kg and includes a monitoring computer that provides noninvasive diagnostic and monitoring information to the user, including device rates, dynamic stroke volumes, calculated cardiac outputs, drive pressure, flow waveforms, and trending information. Device status and patient related alarms ( eg , low cardiac output) are also displayed on the console.