My son has the same or similar device from Thoratec. His is a bit bigger than a D cell battery and only pumps for the left ventricle. It is a continuous flow pump. He also does not have a discernable pulse. We had to take him to the local fire station so that they would understand about his pump if something happened to him. He is 16 yrs old and as you can see from my avatar, the pump has not slowed him down much. He does not race motorcycles anymore, but he is racing his little 4 wheeler. I did not want him to have a heart transplant because he was young and I hoped that he could miraculously recover. Apparently, miracles do happen, he is having the pump taken out in March because his heart looks much better now.