The eccentric behavior of my not really full sized aortic pumps!

My aortic pumps is (are?) behaving very strange lately. As soon as I sit or lie down, it starts crashing itself into my chest and my back. Like it wants to break free of my ribs and fly away. Like this shell doesn't have enough room for it to grow. And this goes on until absolute exhaustion.

Now here is my dilemma: when I am tired I want to sit/lie down to rest and reinforce. But if I do that before the state of absolute exhaustion, my heart starts beating like battle drums to makes sure I will eventually reach that state. I may as well let it break free...!