Left ventricular assist device complications

Background

  • Developed in 1960s and used as a bridge to Cardiac Transplant but have evolved into permanent or “destination therapy.”
  • Indication is New York Heart Association class 4 heart failure, ejection fraction <25%, VO2 max less than 15 among other criteria.[1]
  • All VADs are pre-load dependent.
  • VADs are ECG independent, unlike ICDs.
VADs have 3 major variables:
  1. Speed
  2. Flow
  3. Power

Mechanism of Action

  • External pump unit outside body with intake channel (blood is drained from the apex of the left ventricle) and output channel (blood is ejected into the aorta). Bypasses left ventricle function. BiVAD bypasses both ventricles.

Special Considerations

  • Patient does not have a pulse due to the mechanics of the device
  • Listen to the heart to hear if the pump is working
Heartmate I
Heartmate II
Thoratec-VAD

Complications

  1. Driveline/Pocket infections: Treat for gram negative and positive coverage. Consider endocarditis for recently transplanted pts.
  2. Pump Thrombosis (due to inappropriate anticoagulation)
    1. Consider heparin/tPA if device thrombus is a high probability or seen on bedside echo
  3. Bleeding (many patients are anticoagulated on the LVAD)
    1. Acquired Von Willebrand disease (similar to patients on dialysis or with aortic stenosis)
    2. Hypercoagulability due to coumadin
  4. Dead Battery for Device
    1. Usually a button to check remaining battery charge
  5. Arrythmias: Okay to defibrillate (front-to-back), but not over pump
  6. Acute Infarction

Devices Overview

  1. HeartMate I or XVE
    1. Use: Destination Therapy
    2. Flow Type: Pulsatile
    3. Pulse: Has pulse but may not match ECG rhythm
    4. Backup Method: Hand Pump
    5. Battery: 12volt MiMH - 10hrs
    6. Defib/Cardioversion: Use hand pump during defib/cardioversion
    7. Anticoagulation: patient on aspirin
  2. HeartMate II
    1. Use: Bridge to transplant or destination therapy
    2. Flow type: axial flow
    3. Backup Method: No external method
    4. Pulse: No palpable pulse or BP. Dopplerable Only
    5. Battery: 14V Li-Ion - 10 hrs
    6. Defib/Cardioversion: No precautions necessary
    7. Anticoagulation: Warfarin
  1. Thoratec VAD
    1. Use: Bridge to Transplant
    2. Flow Type: Patient will have pulse and BP but may not match ECG rhythm
    3. Backup Method: No external method
    4. Battery: 12V lead acid gel battery - 7.2 Ah - up to 3 hrs
    5. Defibrillation/Cardioversion: No precautions
    6. Anticoagulation: Warfarin

Management

  1. Auscultate for hum or whirling sound. (indicates lvad is on)
  2. Check MAP (~65-90) since patient has non-pulsitile flow, there will be no pulse.
  3. Assess perfusion (mental status, skin temp/color, and machine flow indicator).
  4. Consider inotropes and after load reduction to improve forward flow.
  5. Fluid challenge for pre-load augmentation.
  6. Place on monitor +/- defibrillate

Urgent Echo: Consider your own bedside ED echo.

References

  1. ↑ Mancini D, Lietz K. Selection of cardiac transplantation candidates in 2010. Circulation. 2010;122(2):173-83.
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