Healthy veins have valves and are supported by calf muscles, which squeeze blood back toward the heart with every step. If those valves become weak, blood pools in the lower legs and causes chronic venous insufficiency. The legs may look heavy, achy and discoloured.
The lymphatic system is the second drainage network. When it becomes blocked or overloaded, fluid rich in proteins collects in the tissues and causes lymphedema. These problems do not always point directly to heart or brain disease, but any long term stagnation of fluid slows circulation and makes it harder for the heart to keep up.
Red flag patterns requiring urgent assistance.
Certain types of swelling are dangerous:
Sudden swelling in one leg, especially with pain, warmth or redness, can signal a clot in a deep vein.
If part of that clot breaks off and travels to the lungs, it can cause chest pain, breathlessness, and even collapse. Swelling that appears or worsens quickly, together with shortness of breath, chest discomfort, rapid heartbeat, confusion or a feeling of drowning in bed may signal acute heart failure or a clot in the lungs. Those situations are emergencies and need immediate medical care-no waiting.