Page 12 - Volume 11 Number 7

Understanding Deep Vein Thrombosis (DVT)
by Dr. Jerrold Seckler
There are two groups of veins that move blood from the lower extremities back to the heart. The first system is superficial and consists of veins lying close to the surface; the other larger system is the deep venous system which, as its name implies, is deep within the leg. The superficial veins communicate with the deep veins and eventually drain into the deep veins near the groin. From there the blood flows back to the heart.
Have you ever wondered how blood in your lower extremities manages to overcome gravity to return it back to the heart? It’s a complex process that involves the pressure generated by the heart’s contractions, valves in the veins that prevent blood from moving in the wrong direction, and contractions of the muscles of the leg that compress the veins and force blood upward against the opposing force of gravity. Because inactivity such as prolonged sitting results in few, if any, leg muscle contractions, persons who are sedentary may have blood pooling in the veins of their lower extremities because that blood isn’t being pushed up towards the heart efficiently.
Pooled blood is more likely to clot and this can result in serious issues. Clots can form in either the superficial or the deep veins. When clots form in the superficial veins, there is usually pain in the leg as well as swelling. Often one can feel the clot along the course of the vein. These superficial clots are usually associated with inflammation and the condition is called thrombophlebitis – “thrombo” means clot, “phleb” is a prefix for vein and “itis” signifies inflammation. While superficial thrombophlebitis may be uncomfortable and result in significant swelling of the leg, as well as long-term leg problems, it is not potentially as serious as deep vein thrombosis, also known as DVT.
The deep veins are quite large and if a clot forms in them, the clot can also be large. In addition to the potential for leg swelling with a DVT, the real risk is that the clot could become dislodged and travel up to the heart. From there, it would be pumped into the pulmonary artery, which takes blood to the lungs to be oxygenated. The clot can completely block the pulmonary artery thereby preventing blood flow to the lungs. This makes oxygenation impossible and the result is sudden death. A clot that forms in one place and moves to another is called an embolus, therefore this condition is called a pulmonary embolus.
What are some of the risk factors for DVT and why is this condition something pilots should be concerned about? While some risk factors like an inherited blood clotting disorder, various malignancies, recent surgery and an age over 60 are not in our control, other risk factors are. Smoking increases the risk, as does obesity. Pilots taking hormone therapy (including birth control pills) are also at higher risk.
10 • KING AIR MAGAZINE
JULY 2017