Ventricular Assist Device Management

Introduction

• Ventricular assist devices (VADs) were originally introduced as a “bridge to transplantation,” but have evolved into permanent or “destination therapy.”
• Essentially, VADs augment cardiac output by having an internal pump with an intake channel (RV, LV or BiV) and output channel (into aorta).
• A percutaneous cable (“driveline”) exits the abdominal wall and connects the internal pump to an external controller, which is connected to an electrical source (batteries or AC-power based unit). The external controller is the brains of the device, containing settings, alarms and diagnostic information about the pump.

Recap Basics

• Most patients have tag located on their controller around their waist indicating what type of device it is, what institution put it in, and a number to call.
  • Imperative to call VAD center/coordinator early on for follow-up, possible transfer and any questions/concerns.
• VADs are preload dependent and afterload sensitive.
  • Suction events (excessive ventricular unloading where venous return is temporarily reduced) can occur leading to reduced CO, increased myocardial work and ventricular arrhythmias, so consider a fluid bolus.
• External controller displays flow, power (watts) and speed.
  • Note: Displayed pump flow is not a measured flow, but a calculation related to the pump power and pump speed. Thus, pump obstructions may not always trigger an alarm as pump power increases, resulting in a normal or even high displayed pump flow.
• Bleeding, pump thrombosis, infection, arrhythmias and pump failure are the main issues encountered from VADs.

  Bleeding

  Acquired vWD (like patient’s with ESRD or aortic stenosis), and always on anticoagulation (warfarin and/or aspirin), so patients are prone to bleeding (most common are GI, nasal and intracranial).

  Pump Thrombosis

  Signs include a VAD working hard (hot on touch with high power), low flow, low MAP, and dilated RV/LV.

  • Consider heparin bolus and tPA in decompensating / peri-coding patient.

  Infection

  Look/feel pump pocket and entry site of driveline, but DO NOT remove. Treat for health-care associated infection including gram negatives and MRSA. Pump endocarditis is also a possibility.

  Arrhythmias

  Get an EKG! Most patients may be talking and in VTach/VFib while pump is working. Okay to defib, but do not place defib pads over the pump (anterior/posterior placement acceptable).

  Pump Failure

  Some patients may decompensate rapidly or tolerate this condition well.

  • Check connections, cables, controller, and batteries (two sources) when VAD alarming.
  • Ask family/patient since they’re the equipment experts.
  • Use caution and consult VAD coordinator before restarting pump, as there is an increased risk of thromboembolism.

Bottom Line/Pearls & Pitfalls

• Always assess airway and intervene if necessary.
• “C” – Circulation: VADs produce a non-pulsatile continuous flow, so some will not have a palpable pulse, and unfortunately, manual BP cannot be obtained. In addition, pulse oximetry is unreliable due to weak/absent pulses.
  • Use Doppler with manual BP cuff and first sound is equivalent to MAP. A-line MAP is the most accurate.
• 5 steps to perform on all VAD patients:
  1. Auscultate for hum or whirling sound.
  2. Check MAP (~65-90) and assess perfusion (mental status, skin temp/color, and machine flow indicator). Consider inotropes if very low, and after-load reduction if too high.
  3. Judicious fluid challenge for pre-load augmentation.
  4. Place on monitor +/- defibrillate
  5. Urgent Echo: Consider your own bedside ED echo.
• Remember that VAD patients often call 9-1-1 for problems unrelated to their VAD, so you shouldn’t get distracted from your usual approach to patient care.

Further Reading

Edited by: Alex Koyfman, MD

Discussion Questions/Future Exploration

• When to do compressions? Lots of opinions regarding this, and always up for discussion.
• Bottom line: CPR not recommended by manufacturers due to fear of dislodgement (some have external manual pumps on controller), but if internal pump NOT working and patient has lost BP/MAP, you must consider it to maintain perfusion to the vital organs.