Heartware LVAD

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HeartWare User Manual [PDF updated on 7/16/18]
HeartWare Powerpoint, Christina van der Pluym, MD

Overview

  • Continuous flow, centrifugal, non-pulsatile device
  • Implanted into the ventricle
  • Designed to draw blood from the LV and propel it through an outflow graft connected to the patient’s aorta
  • Implant Strategy:
    • LVAD:
      • inflow -> LV Apex
      • Outflow graft àascending Ao
    • RVAD:
      • Inflow àRV or RA
      • Outflow graft àPA

HeartWare LVAD

Centrifugal pump surgically placed into the LV or RV apex. Single magnetically driven centrifugal pump that ‘sucks’ blood from the LV and pumps it into the driveline up to ascending aorta. This decompresses the LA and LV well. Particularly in restrictive or hypertrophic cardiomyopathies, the septum may impinge on inflow jet, causing suction event. Treat with volume, position change or other maneuvers to increase LV preload, acutely may decrease RPMs to relieve suction.

High-Critical Alarms (Flashing Red)

  • VAD stopped –> Connect Driveline
  • VAD stopped –> Change Controller (must also attach power to work)
  • Critical Battery (1 or 2) –> Change the appropriate battery
  • Controller Failed –> Change Controller

Medium Priority Alarms (Flashing Yellow)

  • Controller fault, high watts, electrical fault, low flow, suction –> Call CICU and VAD attending • Low Battery (1 or 2) –> Change appropriate battery
  • Power Disconnect (1 or 2) –> Reconnect power sources

  • Operating speed (RPMs) = rotational speed of centrifugal pump head (usual 2400-3200). This parameter is set by team.
  • Operating power (watts) = power required to achieve rotational speed. This parameter is measured directly by device. May increase with afterload, suction events, and thrombus formation.
  • Calculated cardiac output (L/min) = calculated based on power consumption, operating speed, and inputted hematocrit.

Controller must always be connected to 2 power sources (generally AC adapter and backup battery). Login password 6873 (‘nurse’ on a phone)

Troubleshooting

Low Flow

If flow waveform amplitude is low (< 2L/Min), consider:

  • Hypovolemia: consider giving volume, holding diuretics, or decreasing RPMs to allow more filling of the RV • Hypotension: check MAP using a Doppler
  • Consider tamponade if pulsus paradoxus If flow waveform amplitude is large (> 4 L/min), consider:
  • HTN: VAD is afterload sensitive and can’t provide forward flow against a higher resistance, therefore blood will be left in the ventricle and waveform will appear wider (recommended MAP < 70)

High flow

  • If combined with high watts, concern for pump thrombosis or inflow/outflow occlusion.

Components

  • Driveline externalized percutaneously and connects HVAD pump to controller and power sources
  • Controller must be connected to two power sources at all time (two lithium ion batteries or AC/DC power adaptor) and programmed by monitor
    • Each battery holds 4-6 hours of battery life when fully charged
  • Monitor displays: Login PW à6873 / “NURSE”
    • Alarms
    • Calculated flow (cardiac output in liters per minute)
      • Taking into account power consumption, operating speed, and inputted hematocrit
        • Hct changes >5% should be changed in monitor
      • Flow rate up to 10L/min
      • Preload driven and afterload sensitive
    • Measured power consumption (Watts)
    • Programmed operating speed (RPMs)
      • Capable of 1800-1400 (optimal 2400-3200)

Patient Management

  • Causes of decreased preload (low flows)
    • RHF
    • Tamponade
    • Hypovolemia
    • Changes in intrathoracic pressure
    • Increased PVR
    • LVAD patients: assess RV function/output
  • frpCauses of increased afterload (low device flows)
    • Pulmonary or systemic HTN
    • Need to update HCT in monitor
  • Waveform Interpretation
    • Low Flow
      • If waveform amplitude small (< 2L/Min) consider:
        • Hypovolemia: consider giving volume, holding diuretics, or decreasing RPMs to allow more filling of the RV
        • Hypotension: check MAP using a Doppler
        • Consider tamponade if pulsus paradoxus
      • If waveform amplitude large (> 4 L/min) consider:
        • Fluid overload or inadequate unloading of the ventricle
        • HTN: VAD is afterload sensitive and can’t provide forward flow against a higher resistance, therefore blood will be left in the ventricle and waveform will appear wider (recommended MAP < 70)
      • Normal flow but high amplitude waveform
        • If waveform amplitude > 4L/min, then consider retrograde flow from the ascending Ao through outflow graft into pump and out of the LV apex inflow cannula, increase RPMs to treat until trough of waveform > 2L/min and amplitude between 2-4L/min
      • High flow
        • Concern for pump thrombosis or inflow/outflow occlusion in setting of high watts
      • Waveform Variability
        • Determine if the peak of the waveform varies with each beat or every few beats
        • Consider ectopic beats or arrhythmia
  • Suction Events
    • Suction occurs when the cannula is too close to the septum, MV, or LV free wall
    • Most likely will occur in the setting of:
      • Hypovolemia
      • RV failure
      • Bradycardia (RV dependent on HR)
      • Poor cannula positioning
    • Alarms
      • Notify VAD Pager #5823 with any medium or high priority alarms; refer to bedside alarm guide or IFU for details of alarms

Infection

  • Driveline exit site changed by experienced group of RNs with VAD Coordinator supervision
  • Infections difficult to treat and may require chronic abx therapy until transplant
  • Increased risk of thrombus/stroke during and infection
  • Limit central line duration and access

 

Emergency Management:

  • Patient may have NO pulse due to continuous flow nature of device
  • Use Doppler & manual cuff to measure MAP at least once per shift
  • Institute ACLS and PALS protocols, pt may receive CPR , if indicated
  • Confirm pump positioning following pt stabilization if chest compressions performed by CXR and echocardiogram
  • Pt may be defibrillated, no need to disconnect from VAD

Clinical Support

  • Page “LVAD” (5823)
  • Intrahospital Website àDepartments and Programs àVAD Program
  • Refer to Intrahospital Transfer Guideline for travel off unit
    1. Heartware 24 hour clinical support: 888-494-6365
    2. Email: cs@heartwareinc.com
    3. Website: heartware.com 

Antithrombosis for ALL VADs

  • Single Provider Management:
    • Page VAD Pager #5823 with any level or prior to any dose titration
  • Draw all labs off non-heparinized lines or by peripheral stick to avoid contamination

Labs/Imaging to consider ordering for ALL VADs

  • Antithrombosis levels, PT, PTT, Fibrinogen, AT3 (if on heparin), INR, TEG w/ PM, VN ASA and Plavix
  • Hemolysis labs: LDH, CRP, Plasma Free Hgb, Urine hemoglobin
  • Infection: CBC, CRP, cultures, UA, chest CT, procalcitonin, US cannula sites
  • Echo: septum midline, RV fxn, ventricular decompression, degree of TR, Ao Valve opening, inflow cannula obstruction, intracardiac thrombus

Concerns for Stroke

  • Immediately call Stroke Stat: 5-2170
    • Arrange head CT as quickly as possible
  • Notify CICU & LVAD Pager #5823
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