As we say goodbye to the scorching summer of 2022, it is worth noting that heat records have been broken across the globe. Unprecedented heat waves have hit the US, Europe, England and China. According to the National Oceanic and Atmospheric Administration July 2022 was the third hottest July on record, June was the sixth warmest and overall the year 2022 is trending as the third warmest year in history. In the midst of all of this hot humid weather, patients flocked to their doctors with lower leg swelling. What are the causes of leg swelling? Why does it occur with greater frequency in the hot summer months?
To understand why the legs swell, we have to review the blood flow to and the drainage from the lower extremities. The arteries bring blood to the legs from heart. The veins drain the blood back to the heart. There are two venous systems in the legs: the deep veins and the superficial veins. How does blood defy gravity and flow back to the heart? As we walk, the contraction of the muscles in the legs causes the blood to be pumped upward and back to the heart. To facilitate the flow, the veins have valves to prevent blood from leaking back. Another conduit is the lymphatic system. This consists of thin tubes and nodes that drain lymph back to the heart. Lymph is a fluid that includes excess fluid, proteins, cells, fats and nutrients. About 20 liters of blood flow to the legs every day. The veins drain about 17 liters back to the heart. The lymph system drains the extra 3 liters. Leg swelling occurs if fluid leaks from the veins or the lymph system because of blockage to the flow or excess pressure within the vessels or the vessels become damaged or dilated.
Leg swelling can be categorized as acute (recent) or chronic. One leg can be affected (unilateral) or both legs (bilateral). There are many causes of leg swelling including deep venous thrombosis (a blood clot in the leg, DVT), chronic venous insufficiency, lymphedema, heart failure, kidney failure, liver failure, infection (cellulitis), cancer, thyroid disease, medications, and pregnancy. Medications include calcium channel blockers (especially amlodipine), prednisone, and non-steroidal anti-inflammatory drugs (such as ibuprofen and naproxen). Leg swelling may be asymptomatic or cause pain, aching, heaviness or fatigue of the leg, skin changes or ulceration of the skin.
DVT may cause leg swelling in the acute phase as a blood clot could block the flow in the deep venous system. Many patients have swelling years after an acute DVT, likely because the blood clot has caused damage to the venous valves. Treatment of DVT is blood thinners such as warfarin, Eliquis, or Xarelto.
Chronic venous insufficiency is a very common clinical problem. In this condition, the venous valves become incompetent, blood refluxes back into an already congested venous chamber, this increases the pressure in the chamber and fluid leaks from the veins into the surrounding tissue. Risk factors include older age (peak incidence in women is 40-49 years and men 70-79 years), smoking, pregnancy, hypertension and varicose veins. Prolonged standing or sitting with the legs in a dependent position also can cause swelling. In this case, the veins are completely filled, the valves float open and fluid leaks out. In addition, warm conditions (such as the hot humid summer weather) tend to aggravate symptoms as the warmth can dilate the veins, causing further venous valvular incompetence. Conversely, cold conditions relieve symptoms. The best test to diagnose the cause of leg swelling is a venous ultrasound. The ultrasound can demonstrate a DVT and can show if there is venous reflux/insufficiency. Chronic venous insufficiency is treated by avoiding prolonged sitting or standing, leg elevation, exercise (walking or calf muscle exercises to help increase the flow) and compression stockings. If swelling persists despite these measures, venous ablation can be performed. Ablation shrinks the refluxing vein, allowing the valves to do their job and decrease or eliminate leaking. Varicose veins are enlarged twisted veins near the surface of the skin. They are usually branches off the superficial or deep vein system. They are quite common (25% of adults have them). Treatment is the same as chronic venous insufficiency but varicose veins can also be surgically stripped or injected with a sclerosing agent to shrivel the vein up. These treatments are more cosmetic than medically necessary. Spider veins are similar to varicose veins, but occur in even smaller surface veins.
Lymphedema may be primary or secondary to another condition. Primary lymphedema occurs with congenital absence or damage to the lymph system. Secondary lymphedema occurs with blockage of the lymph system due to cancer, prior pelvic surgery, radiation, or trauma. Lymphedema can be differentiated from chronic venous insufficiency by physical exam. In lymphedema there is no pitting of the edema, swelling affects the back of the foot, the toes are involved and there is skin thickening. Lymphedema is usually painless. Treatment includes compression stockings and pneumatic pump compression.
So don’t get pumped up over lower leg swelling. See your doctor and get a diagnosis. Then follow the treatment plan to avoid any long-term complications. Keep in mind that cooler weather and relief is coming.
