An estimated 150,000 patients in the Western World require heart transplantation every year, while only 4,000 (2.5%) of them actually receive a donor heart [1]. This lack of available donors for heart transplantation has led to a large effort since the 1960s to develop an artificial mechanical heart as an alternative to heart transplant. Most end stage cardiac failures result from cardiac disease or tissue damage of the left ventricle. After this failure, the ventricle is not strong enough to deliver an adequate supply of oxygen to critical organs. A left ventricular assist device (LVAD) is a mechanical pump that does not replace the native heart, but rather works in concert with it. An LVAD can effectively relieve some strain from a native heart, which has been weakened by disease or damage, and increase blood flow supplied to the body to maintain normal physiologic function. The inlet to the LVAD is attached to the native left ventricle, and the output of the assist pump rejoins the output of the native heart at the aorta, as shown in Figure 1. Blood flow from both the aortic valve and the assist pump combine and flow through the body. The clinical effectiveness of LVADs has been demonstrated; however, all of the currently available pumps have a limited life because of either the damage that they cause to blood or their limited mechanical design life.
Quantitative blood flow estimation in vivo by optical speckle image velocimetry
