How Thrombosis Develops

Thrombosis — a common and potentially life-threatening condition

While haemostasis is necessary for survival, the pathological formation of a blood clot, or thrombosis, poses significant health risks. Thrombosis plays a role in heart attacks, ischaemic stroke, cardioembolic stroke in patients with atrial fibrillation (AF), and venous thromboembolism (VTE).^{5, 8, 18}

In addition to posing a risk of a life-threatening pulmonary embolism (PE), VTE also can lead to long-term complications. These potential complications include post-thrombotic syndrome (PTS) and pulmonary hypertension.⁸ Thromboprophylaxis in patients at high risk, rather than treatment of deep vein thrombosis (DVT) after it develops, is the optimal approach to minimising the risk of these complications.

VTE: a frequent complication of major orthopaedic surgery

VTE is the most frequent serious complication following hip and knee replacement surgery. It is the most common cause for rehospitalisation in this patient group.^{3, 19}

DVT: when thrombosis develops in a vein

The most common type of VTE is deep vein thrombosis (DVT), occurring in veins deep within the muscles of the leg and in the pelvis. Some of the recognised factors that increase the risk of DVT include major surgery (such as hip or knee replacement), cancer, inherited abnormalities in the blood-borne proteins involved in coagulation, and hospitalisation for a major medical illness.²⁰

Deep vein thrombosis

PE: a life-threatening complication of DVT

Thromboembolism occurs when part or all of a thrombus breaks away from the blood vessel wall. This clot (now called an embolus) is then carried in the direction of blood flow. Patients with DVT are at risk of PE, a life-threatening event. In Europe, PE causes more than half a million deaths each year.¹² This is more than twice the number of people who die from AIDS, breast cancer, prostate cancer, and road traffic accidents combined.²¹

Pulmonary embolus

Thrombosis and AF

Atrial Fibrillation (AF) is the most common arrhythmia seen in clinical practice.²² Without appropriate anticoagulant treatment, most patients with AF are at increased risk of cardioembolic stroke.

Thrombosis and coronary artery disease

Cardiovascular disease is the leading cause of death in industrialised countries. Coronary artery disease (CAD) is the most common form of cardiovascular disease. In CAD, atherosclerosis damages the coronary artery wall, predisposing to thrombus formation. The symptoms and severity of acute coronary syndromes (unstable angina and myocardial infarction) vary depending on the degree to which thrombi occlude the coronary arteries.^{5, 23, 24, 231}

Gross pathology: coronary bypass graft with thrombosis

Coronary thrombosis

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Article references

5 - 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.
8 - Tapson VF. Acute pulmonary embolism. N Engl J Med. 2008;358(10):1037-1052.
18 - Waldo AL. Anticoagulation: stroke prevention in patients with atrial fibrillation. Med Clin North Am. 2008;92(1):143-159, xi.
3 - 1. 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.
19 - Harkess JW, Arthroplasty of hip. In: Canale ST, ed. Campbell’s Operative Orthopedics. 10th ed. Philadelphia, PA: Mosby, Inc; 2003. Available at www.mdconsult.com. Accessed February 12, 2008.
20 - Bates SM, Ginsberg JS. Clinical practice. Treatment of deep-vein thrombosis. N Engl J Med. 2004;351(3):268-277.
12 - Cohen AT, Agnelli G, Anderson FA, et al; VTE Impact Assessment Group in Europe (VITAE). Venous thromboembolism (VTE) in Europe. The number of VTE events and associated morbidity and mortality. Thromb Haemost. 2007;98(4):756-764.
21 - Fitzmaurice DA, Murray E. Thromboprophylaxis for adults in hospital. BMJ. 2007;334(7602):1017-1018.
22 - Fuster V, Rydén LE, Cannom DS, et al. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation. 2006;114(7):e257-e354.
23 - Bassand JP, Hamm CW, Ardissino D, et al; Task Force for Diagnosis and Treatment of Non-ST-Segment Elevation Acute Coronary Syndromes of European Society of Cardiology. Guidelines for the diagnosis and treatment of non-ST-segment elevation acute coronary syndromes. Eur Heart J. 2007;28(13):1598-1660.
24 - Rosamond W, Flegal K, Furie K, et al; American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Heart disease and stroke statistics―2008 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation. 2008;117(4):e25-e146.
231 - Lloyd-Jones D, Adams RJ, Brown TM, et al; American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Heart disease and stroke statistics—2010 update: a report from the American Heart Association. Circulation. 2010;121(7):e46-e215.

Haemostasis: The prevention of blood loss, either by the physiological properties of vasoconstriction and coagulation or by surgical means.
Hypertension: Persistently high arterial blood pressure. Hypertension may have no known cause (essential or idiopathic hypertension) or be associated with other primary diseases (secondary hypertension). This condition is considered a risk factor for the development of heart disease, peripheral vascular disease, stroke, and kidney disease.
Ischaemic stroke: Potentially fatal brain damage due to interrupted blood supply to the brain caused by thrombosis or an embolism.
Post-thrombotic syndrome: A syndrome that can follow a vascular thrombosis. Clinical signs and symptoms of this syndrome include chronic pain, swelling, oedema, discolouration, and in severe cases, venous ulceration. It is likely that valvular incompetence is associated with the clinical manifestations of post-thrombotic syndrome.
Thromboprophylaxis: The use of medication or medical devices to prevent the formation of blood clots.
Venous thromboembolism: A condition in which a blood clot (thrombus) forms in a vein, which in some cases then breaks free and enters the circulation as an embolus, finally lodging in and completely obstructing a blood vessel, e.g., in lungs causing a PE. The term encompasses both DVT and PE.
Arrhythmia: Any variation from the normal rhythm of the heart beat (e.g., sinus arrhythmia, premature beat, heart block, atrial fibrillation, atrial flutter, pulsus alternans, and paroxysmal tachycardia).
Angina: Heart condition characterised by intermittent chest pain. Angina usually results from coronary artery disease and may further be classified as stable or unstable angina. Stable angina refers to the more common understanding of angina related to myocardial ischemia. Unstable angina may occur unpredictably at rest which may be a serious indicator of an impending heart attack.
Coronary artery disease: Coronary artery disease (CAD) is the end result of the accumulation of plaques within the walls of the arteries that supply the muscle of the heart with oxygen and nutrients. The process by which the coronary arteries become narrowed or completely occluded is known as atherosclerosis.