a lower part of the heart
The apex
the apex
The apex of the heart is the most inferior part of the heart.
If you cut the heart so that there is a superior and inferior part the section is a transverse section.
the apex
Inferior part of the aorta
The Apex
Inferior Venacava
The upper most anterior / inferior connecting part of the Heart to the Arteries.
Inferior.
Inferior vena cava
The apex is the lowest part of the heart, and is formed by the most inferior part of the left ventricle. So to answer your question, inferiorly.
The apex of the heart is inferior to the rest of the heart. The base is superior to the rest of the heart.
If you mean the heart's apex, it is close to the inferior aspect of the heart. If you mean the lung's apex, it is superior to the heart.