Heart failure is a common condition, and the number of people with advanced disease continues to increase. We need new treatments that improve patients' symptoms and extend life. Recently the new CircuLite Synergy pump has come into use. It is the smallest pump manufactured to date and does not cover the full work of the heart, instead providing "partial" support. One interesting thing about this is that taking some strain off the heart might allow the muscle to repair and rebuild its own strength. This process is called reverse remodelling, and is the topic of this research. Our hypothesis is that "partial" support improves patients' symptoms and causes improvement in heart muscle function. We also want to examine the best techniques for assessing this, including new scanning and molecular tests, and study some practical aspects of the pump to do with blood clotting.