About the data: We used the family income data from the 2013 American Community Survey. This counts only families, which the government defines as households with two or more people related by birth, marriage or adoption. The graph focuses on families living in the country's 30 most populous cities.
The higher pressure causes swelling in the legs and feet. Congestive heart failure, a condition in which the heart can no longer pump efficiently, causes fluid buildup in the lungs and other parts of the body. Swelling is often most visible in the feet and ankles. Pregnancy can cause edema in the legs as the uterus puts pressure on the vena cava, a major blood vessel that returns blood to the heart from the legs. Fluid retention during pregnancy also can be caused by a more serious condition called preeclampsia.
Ankle edema is a swelling over either one or both ankles. Swelling of the ankles is quite common, especially if you have been travelling for a long duration. It occurs due to accumulation of excessive fluid in the tissues of the ankle and feet, a condition referred to as ankle edema. As the amount of fluid accumulates, the swelling may rise up into the leg. Due to mans erect posture, the blood in the veins of the leg has to move against gravity towards the heart. This unidirectional flow of blood is ensured by the presence of valves in the veins and the contractions of the leg muscles.