A dilated ascending aorta is a section of the aorta vessel that extends from aorta root to the arch aorta. It is the beginning of a main vessel that carries blood to be distributed to the body. If the ascending aorta is greater than 4.0 cm it is considered an aneursym, and if it grows quickly about .05 cm per year it could be problematic and require treatment. If the aorta grows to 5.0 cm, it also may require intervention.
Hypertension refers to blood pressure and it relates to the amount of resistence the heart pumps against when pumping blood into circulation. The more resistance usually from narrowing of the vessel due to occlusions, the higher the blood pressure to pass blood through the vessel.
The connection with dilated aorta and hypertension is that the dilated aorta's condition can have a harmful effect on the dilated aneursym because the vessel wall be thinner than normal and a "pounding" of blood against the wall can cause damage.
Hope this helps, and if you have any further questions or comments you are welcome to respond. Thank you,
Ken