When Thrombosis Occurs
Even a small clot poses a great threat
Thromboembolic disorders are a major cause of morbidity and mortality worldwide. Venous thromboembolism
(VTE), which includes both deep vein thrombosis
(DVT) and pulmonary embolism (PE), is the third most common cardiovascular disorder after ischaemic heart disease and stroke, and is estimated to contribute to about 10% of all deaths that occur in the hospital.6, 37
In addition to posing a risk of a life-threatening PE
also can lead to long-term complications. These potential complications include post-thrombotic syndrome (PTS) and pulmonary hypertension.38, 39
in patients at high risk, rather than treatment of DVT
after it develops, is the optimal approach to minimising the risk of these complications.6
Normal blood clotting: an essential survival process
The normal physiological response that prevents significant blood loss following vascular injury is called haemostasis.33
Blood vessel injury triggers the following sequence:
- The vessel constricts to reduce blood flow.
- Circulating platelets adhere to the vessel wall at the site of trauma.
- Platelet activation and aggregation, coupled with an intricate series of enzymatic reactions involving coagulation proteins, produces fibrin to form a stable haemostatic plug.33
This finely tuned process serves to maintain the integrity of the circulatory system.40
However, the process can go out of balance, leading to significant morbidity and mortality.41
Abnormal haemostasis or excessive coagulation
While haemostasis is necessary for survival, the pathological formation of a blood clot, or thrombosis
, poses significant health risks. VTE
is one of the most frequent serious complications following major orthopaedic surgery
, such as elective hip or knee replacement surgery.6
Multiple factors increase patient risk for VTE
is associated with cancer, trauma, and surgery. In some cases, described as idiopathic, a patient has no clear exposing risk factor (ie, no triggering event).14
And if a patient has many risk factors, there is generally a cumulative impact on VTE
- 6 - Geerts WH, Bergqvist D, Pineo GF, et al. Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest. 2008;133(6 suppl):381S-453S.
- 37 - Sandler DA. Martin JF. Autopsy proven pulmonary embolism in hospital patients: are we detecting enough deep vein thrombosis? J R Soc Med. 1989;82(4):203-205.
- 38 - Schulman S, Lindmarker P, Holmström M, et al. Post-thrombotic syndrome, recurrence, and death 10 years after the first episode of venous thromboembolism treated with warfarin for 6 weeks or 6 months. J Thromb Haemost. 2006;4(4):734-742.
- 39 - Pengo V, Lensing AW, Prins MH, et al; Thromboembolic Pulmonary Hypertension Study Group. Incidence of chronic thromboembolic pulmonary hypertension after pulmonary embolism. N Engl J Med. 2004;350(22):2257-2264.
- 33 - Colman RW, Clowes AW, George JN, Goldhaber SZ, Marder VJ. Overview of hemostasis. In: Colman RW, Clowes AW, George JN, Goldhaber SZ, Marder VJ, eds. Hemostasis and Thrombosis: Basic Principles and Clinical Practice. 5th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2006:1-16.
- 40 - Adams GL, Manson RJ, Turner I, Sindram D, Lawson JH. The balance of thrombosis and hemorrhage in surgery. Hematol Oncol Clin North Am. 2007;21(1):13-24.
- 41 - Heit JA. Venous thromboembolism: disease burden, outcomes and risk factors. J Thromb Haemost. 2005;3(8):1611-1617.
- 35 - Fuster V, Moreno PR, Fayad ZA, Corti R, Badimon JJ. Atherothrombosis and high-risk plaque: part I: evolving concepts. J Am Coll Cardiol. 2005;46(6):937-954.
- 42 - Waldo AL. Anticoagulation: stroke prevention in patients with atrial fibrillation. Med Clin North Am. 2008;92(1):143-159.
- 43 - Merli GJ. Pathophysiology of venous thrombosis, thrombophilia, and the diagnosis of deep vein thrombosis-pulmonary embolism in the elderly. Clin Geriatr Med. 2006;22(1):75-92.
- 14 - Turpie AG, Chin BS, Lip GY. Venous thromboembolism: pathophysiology, clinical features, and prevention. BMJ. 2002;325(7369):887-890.
- 44 - Kakkar AK. Prevention of venous thromboembolism in general surgery. In: Colman RW, Clowes AW, George JN, Goldhaber SZ, Marder VJ, eds. Hemostasis and Thrombosis: Basic Principles and Clinical Practice. 5th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2006:1361-1367.
- 45 - Motte S, Samama CM, Guay J, Barré J, Borg JY, Rosencher N. Prevention of postoperative venous thromboembolism. Risk assessment and methods of prophylaxis. Can J Anaesth. 2006;53(6 suppl):S68-S79.
- Formation of a clot inside a blood vessel.
- Venous thromboembolism
- A disease process beginning with a blood clot occurring within the venous system, including deep vein thrombosis and pulmonary embolism.
- Pulmonary embolism
- A potentially fatal condition caused by a blood clot blocking a vessel in the lung: usually the clot originates from a DVT in the legs. PE can result in permanent lung damage.
- Preventative treatment for blood clotting.
- Deep vein thrombosis
- A blood clot in a deep vein, usually resulting from damage to the vein or blood flow slowing down or stopping. Usually DVTs are found in the leg, but can also be in the arm.
Distal DVTs are found in deep veins of the calf, and are the most common type of DVT.
Proximal DVTs are found in the legs above the calf muscle up to the waist.
- Major orthopaedic surgery
- Major operations on the bones or joints including total hip or knee replacement surgery.
- Atrial fibrillation
- A heart rhythm disorder where chambers in the upper heart (atria) beat more rapidly than those in the lower section of the heart. Blood is not pumped out of the upper chambers completely during beating, and may pool and form a clot. A stroke results if a section of clot dislodges from the upper chambers and becomes lodged in the brain.