The most important part of the heart is all of it. There all equally as important.
valves
The apex of the heart is the most inferior part of the heart.
That which is at the heart of something is its essence, the most important and most characteristic part of the thing. It is what makes it what it is.
no heart
The eardrums.
The heart.
Most of Englands energy is imported.
THE HEART WORKS AS A WHOLE. One part cannot be more important than another.
There are two pacemakers in the heart. One (which is the main pacemaker of the heart) can be found in the upper right-most part of the right atrium and the other one can be found in the center most part of the heart, inside the atrio-ventricular wall.
the heart of Dresden
Most Green tea is imported from China. Most Black tea is imported from Sri Lanka and Kenya.
The upper most anterior / inferior connecting part of the Heart to the Arteries.