Pulse

It is the episodic squeezing of our heart, the pressure difference between systole and diastole, that give rise to the pulses we feel in our wrists, our temples and our throats. The pulse is the defining characteristic of life. Every so often someone comes up with a design for an artificial heart that pumps without need of a pulse. How would it feel, I wonder, to have blood that moved continuously through the body; not the ebb and flood of a tide, but a ceaseless, circular flow?

From Diary by Gavin Francis, London Review of Books, 6 March 2014


Image: MRI picture of tissue fibres around left ventricular cavity, captured using diffusion tensor imaging, which tracks the movement of fluid through tissue, using different colours to represent the orientation of the strands.  Laurence Jackson