Left ventricular assist devices (LVAD) are surgically implanted devices that aid pumping blood in patients with severe refractory cardiac failure. It may be used as a bridge to cardiac transplantation, or as destination therapy in patients who are not a transplant candidate.
The LVAD acts as a conduit, diverting blood from the left ventricle, through a mechanical pump, to the aorta. There are several different brands available; one commonly used device is the HeartMate II (Thoractec, Pleasanton, California) pictured in this article. The HeartMate II consists of an inflow cannula that diverts blood from the apex of the left ventricle into a pump. The pump then propels blood forward through an outflow Dacron graft to the ascending aorta. An electrical cable connects the LVAD to an external power source carried with the patient.
First generation devices pumped blood in a pulsatile manner, but current devices now pump with continuous flow. As a result, patients have no palpable pulse or a greatly diminished pulse.
Stroke is one of the more common complications due to the risk of thrombus formation within the LVAD components, therefore patients are maintained on anticoagulation.
Basic understanding of LVADs is important in radiology for several reasons:
- it is prudent to recognise the device on thoracoabdominal imaging
- Doppler waveforms throughout the arterial system are significantly altered (see: Doppler ultrasound findings with LVAD)
- anticoagulation generally cannot be withheld or reversed for LVAD patients undergoing interventional radiology procedures due to the stroke risk, though in some instances the INR may be lowered to a degree
- 1. Cervini P, Park SJ, Shah DK et-al. Carotid Doppler ultrasound findings in patients with left ventricular assist devices. Ultrasound Q. 2010;26 (4): 255-61. doi:10.1097/RUQ.0b013e3181fe2a97 - Pubmed citation
- 2.Horton SC, Khodaverdian R, Powers A et-al. Left ventricular assist device malfunction: a systematic approach to diagnosis. J. Am. Coll. Cardiol. 2004;43 (9): 1574-83. doi:10.1016/j.jacc.2003.11.055 - Pubmed citation