Hypertension
When you're diagnosed with hypertension, an elevated amount of pressure is being placed along your arterial walls, resulting in high blood pressure. Most of the time, this is due to an increased amount of resistance that develops within your arteries, making it more and more difficult for your heart to pump blood. Over time, this high blood pressure may lead to three very specific complications that could cause you to experience some level of edema, which is a swelling of tissue due to fluid accumulation.
Heart Failure
With hypertension, the elevated pressure of your blood causes your heart to work much harder than normal to transport oxygen and other nutrients throughout the body. If left untreated, especially for prolonged periods of time, the muscles of your heart can actually begin to experience a thickening. Over time, this can eventually result in heart failure. But not only can this failure affect the way in which blood is pumped from your heart to other organs, it can also impede the return of deoxygenated blood from the body to your heart. When this occurs, blood essentially backs up and begins to accumulate within the tissue of your feet, ankles and legs, causing them to swell.
Kidney Disease
The second way in which edema may be related to hypertension involves your renal function. Hypertension doesn't necessarily just affect those arteries nearest the heart; it can also cause an increased pressure within the blood vessels to your kidneys. This can damage the nephrons, which affects the way in which fluid is eliminated from the blood. This causes an increase in pressure, and blood may back up and begin to accumulate within the tissue of your feet, ankles and legs, causing them to swell much like in heart failure.
Vessel Damage
Though not as common as the other two complications of hypertension, it's also possible for this increased blood pressure to damage the blood vessels of the legs. When this occurs, your body may not be able to move the normal amount of blood back to your heart, leaving some to accumulate in the tissue of your feet, ankles and legs. Over time, the accumulation will cause these areas of the body to swell.
