Deep Vein Thrombosis: Clinical Features & Risk Factors

Clinical Features of Deep Vein Thrombosis (DVT)

• DVT is often asymptomatic.
• Symptomatic presentation includes unilateral tenderness/pain, swelling/oedema, and erythema.
• The affected calf may feel warmer, and ankle oedema may be visible.
• Pain in the calf on dorsiflexion of the foot can occur.
• Iliofemoral DVT may cause severe pain, thigh swelling, and ankle oedema.
• Complete occlusion can lead to cyanotic discoloration and severe oedema, rarely progressing to venous gangrene.
• Pulmonary embolism can occur when thrombus fragments (emboli) lodge in the pulmonary circulation.
  • Pulmonary embolism is more frequent with iliofemoral thrombosis.
  • Pulmonary embolism is rare when the thrombus is below the knee.
  • Signs of a pulmonary embolism include sudden shortness of breath, chest pain, and tachycardia, requiring emergency intervention.

Risk Factors for Thrombo-Embolism

• Previous DVT/PE or varicose veins (valve failure between deep and superficial venous systems, dilated and tortuous superficial veins)
• Elderly (over 60), obese (venodilation), smoker
• Long air travel, general anaesthesia, prolonged bed rest, recent myocardial infarction/heart failure, pregnancy/recent childbirth (flow stasis)
• Trauma/surgery (especially pelvis, hip, lower limb), inflammation (phlebothrombosis), Behcet's Syndrome (vein/joint inflammation, multisystem involvement with oral/genital ulcers, eye inflammation, and skin lesions) leading to damage to vessel wall and exposed collagen
• Antithrombin deficiency, oral contraceptive pill use, sickle cell disease, malignancy causing altered blood constituents and a hypercoagulable state

Prophylactic Measures for Post-Operative DVT Prevention

• Identify high-risk patients
• Anticoagulation:
  • Low molecular weight heparin (increased bioavailability, longer half-life, once-daily dose) for those with MI/heart failure or pelvis/hip/leg surgery
  • Warfarin
• Careful positioning and padding on the operating table
• Compression stockings and boots
• Adequate fluid replacement
• IVC (inferior vena cava) filters
• Early ambulation (walking), with most DVTs occurring within the first 72 hours post-surgery
  • Leg exercises are encouraged
  • Avoid prolonged sitting in a chair with legs immobilized on a stool

Arterial vs. Venous Thrombosis

• Arterial thrombosis results from turbulent blood flow.
• Venous thrombosis results from sluggish blood flow.

Thrombosis and Blood Constituents

• Changes in blood constituents can shift the hemostatic equilibrium towards thrombosis.
• Increased platelet count and procoagulant factors increase the risk of thrombosis.

Progression of Thrombosis

• Thrombosis can progress to embolisation.

Embolisation

• Thrombi detach and travel through the circulation until they reach a vessel with a smaller lumen than the thrombus itself.
• The thrombus acts as a plug, lodging in the vessel and potentially causing pulmonary embolism in the lungs.

Heart Failure

• Heart failure occurs when the heart cannot pump blood at a rate the body requires.
• Or when the heart cannot fill quickly enough to match demand, or cannot pump the blood out effectively.

Causes of Heart Failure

• Pump failure due to heart muscle disease, restricted filling, or inadequate heart rate
• Excessive preload, such as in mitral regurgitation or fluid overload
• Chronic excessive afterload, such as in aortic stenosis or hypertension

Symptoms of Left-Sided Heart Failure

• Pulmonary congestion
• Restlessness
• Orthopnea

Symptoms of Right-Sided Heart Failure

• Fatigue
• Weight loss/gain
• Enlarged liver/spleen

Overview of the clinical features and risk factors associated with deep vein thrombosis (DVT). Includes symptomatic presentation with pain, swelling and erythema. Also includes risk factors such as previous DVT/PE or varicose veins.