Causes of Deep Bone Thrombosis
Dear mirror doctor I am a very active 46-year-old man who drives to and from work with no problems. I noticed a gradual increase in the size of my right leg over a period of one week.
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For the first two days, the swelling was not painful but started becoming painful from the third day.
I noticed that the leg had become shiny and obviously bigger than the left one. Initially, I pinned it on possible awkward position during sleep but got worried when it became painful.
I consulted a physician who after a series of tests diagnosed me with deep vein thrombosis.
Please doctor, what causes this thrombosis and how can it be prevented? Yaw, Alhaji, Accra
Dear Yaw, Deep vein thrombosis, commonly referred to as DVT, is the presence of blood clot (known in medical parlance as a thrombus) in one of the deep veins that return blood to the heart from the rest of the body.
I hope we all remember from biology class that veins return blood to the heart while arteries transport blood from the heart. DVT most commonly involves the deep veins of the leg or arm.
It is one of the most prevalent medical problems today.
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Lower-extremity or lower limb, DVT is the most common venous thrombosis, with a prevalence of one case per 1000 population.
In addition, it is the underlying source of 90 per cent of acute emergency called pulmonary embolism where the blood clot dislodges from the deep veins and ends up in the lungs.
Early recognition and appropriate treatment of DVT and its complications can save many lives.
The venous system in the peripheries of our body, called the peripheral venous systems, functions both as a reservoir to hold extra blood and as a conduit to return blood from the periphery to the heart and lungs.
Unlike arteries which possess three well-defined layers, most veins are composed of a single tissue layer. Only the largest veins possess internal elastic membranes, and this layer is thin and unevenly distributed, providing little buttress against high internal pressures.
The correct functioning of the venous system depends on a complex series of valves and pumps that are individually frail and prone to malfunction.
Primary collecting veins of the lower extremity are passive, thin-walled reservoirs that are tremendously distensible.
Most are surrounded by loosely bound fatty tissue that is easily displaced. These veins can expand to accommodate large volumes of blood with little increase in back pressure.
Blood flow from these collecting veins is via secondary conduit veins which have thicker walls and so are less distensible.
Most of these veins belong to the deep venous system, through which all venous blood must eventually pass through on its way to the heart.
Blood flow from these veins depends on a complex array of valves and pumps, often referred to as the “peripheral heart,” that functions by pushing blood upward from the feet against gravity.
Three factors are critically important in the development of blood clot: (1) stagnation of blood in the veins, (2) activation of blood clotting mechanisms, and (3) damage to the vein.
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Stagnation of blood in the veins can occur as a result of anything that slows or obstructs the flow of venous blood.
This results in an increase in thickness of the blood with formation of small clots, which are not washed away by fluid movement; these clots may then grow and propagate.
Damage to the lining of the vein may be from within the vein (intrinsic) or from external traumatic factors (extrinsic). It may result from accidental injury or activities of a surgeon.
Sometimes, subtle changes in the chemical balance of the blood predispose it to clot easily.
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This leads to formation of clots in the deep veins.
In addition, decreased vein wall contractility and vein valve dysfunction contribute to the development of what is known as chronic venous insufficiency, where the valves are not able to function properly to propel the blood to flow forward thereby allowing some blood to flow back, causing engorgement of these vessels.
I will continue next week.
astom2@yahoo.com