VAD thrombosis: A Must Know VAD Complication

The HeartMate left ventricular assist device (LVAD) is one of the most frequently placed LVADs today. Originally, it was thought to have a lower incidence of thrombosis due to its mechanical design. However, a recent multi-center study published in the NEJM reported a dramatic increase in the rate of thrombosis since 2011 in the HeartMate II device.  The report found:

• An increase in pump thrombosis at 3 months after implantation from 2.2% to 8.4%

• The median time from implantation to thrombosis was 18.6 months prior to March 2011, to 2.7 months after.

Pump thrombosis is a major cause of morbidity and mortality (up to almost 50%!!) and is a can't miss diagnosis.  It's important to keep thrombosis on the differential for any VAD patient presenting with:

• Power spikes or low pump flow alarms on the patient's control box

• Pump (VAD) failure

• Recurrent/new heart failure

• Altered mental status

• Hypotension (MAP < 65)

• Signs of peripheral emboli (including acute CVA)

Useful lab findings suggestive of thrombosis include:

• Evidence of hemolysis

• LDH > 1,500 mg/dL or 2.5-3 times the upper limit of normal

• Hemoglobinuria

• Elevated plasma free hemoglobin

Bottom Line: In the patient with suspected VAD thrombosis, it is important to contact the patient's VAD team immediately (CT surgeon, VAD coordinator/nurse, VAD engineer).  Treatment should begin with a continuous infusion of unfractionated heparin, while other treatment options can be discussed with the VAD team.

References

Starling RC, Moazami N, Silvestry SC, et al. Unexpected Abrupt Increase in Left Ventricular Assist Device Thrombosis. N Engl J Med. 2013.

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