meditation on the heartbeat Usually we use an anchor in meditation, the breathing being the most common. Sometimes when I focus on that I feel my heartbeat taking my attention, so I thought about using that as an anchor, does anyone know if there is a meditation technique that uses the heartbeat?

PS: I'm aware this does not apply to all types of meditation
You can use it if it serves you the purpose of one-pointedness attention.
But you should remember the benefits of using the breath as your point of attention.
The breath is both a concious and unconcious function and because of that it serves as a bridge bwtween them.
Also in Tibetan Buddhism conciouness is said to "ride" in the winds (prana) of the body so by focusing in the breath you are also focusing in your mind.
Once you have achieved mindfulness thru the attention to your heart beat, it is better to switch to your breath.