- 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.
- 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.
- 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.
- 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.
- 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:
- Auscultate for hum or whirling sound.
- 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.
- Judicious fluid challenge for pre-load augmentation.
- Place on monitor +/- defibrillate
- 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.
Felix SE, Martina JR, Kirkels JH, Klöpping C, Nathoe H, Sukkel E, et al. Continuous-flow left ventricular assist device support in patients with advanced heart failure: points of interest for the daily management. Eur J Heart Fail 2012;14:351–6.
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.