Anatomically, the left ventricle empty directly into the aorta. Therefore the probe will pass through the aortic valve to exist in left ventricle.
The left ventricle pumps oxygenated blood out of the heart through the aorta into the systemic circulation. Consequently, there must be a closed link between the chamber which stores and empty the blood (left Ventricle), and the vessel which conveys blood to the target areas (Aorta) in the systemic circulation.
check the attachments for clearer picture of this.
