What is a mural thrombus?

Mural Thrombus: Definition, Management, and Clinical Significance

Mural thrombus is a blood clot that forms on the inner wall of a blood vessel or cardiac chamber, extending from the wall into the vessel lumen, potentially causing partial or total occlusion with or without clinical symptoms. 1, 2

Pathophysiology and Locations

Mural thrombi can develop in various cardiovascular locations:

• Cardiac chambers: Most commonly in the left ventricle after anterior myocardial infarction (detected in up to 24% of anterior MI patients by cardiac MRI) 2
• Blood vessels: Can form in arteries (particularly the aorta) or veins, including those with central venous catheters 1
• Catheter-related: Forms around central venous catheters, extending into the vessel lumen 1

The formation mechanism involves:

• Blood stasis (e.g., in areas of wall motion abnormalities after MI)
• Endothelial damage (e.g., from catheter placement or atherosclerosis)
• Hypercoagulability (often in patients with underlying prothrombotic disorders) 2, 3

Clinical Significance and Complications

Mural thrombi pose significant risks:

• Embolization: Fragments can break off and cause distant embolic events
  • Pulmonary embolism (5-14% incidence with upper extremity venous thrombosis) 1
  • Cerebral infarction (occurs in ~10% of untreated LV thrombus patients) 2
• Vessel occlusion: Can cause partial or complete obstruction of blood flow
• Recurrent thrombosis: DVT recurrence rates of 2-5% 1
• Post-phlebitic syndrome: Incidence range 10-28% with upper extremity venous thrombosis 1

Diagnosis

Detection methods vary by location:

• Cardiac mural thrombi:

  • Cardiac MRI (highest sensitivity, detecting 12.3% of LV thrombi vs. 6.2% with standard echocardiography) 2
  • Contrast echocardiography (significantly improves detection) 2

• Vascular mural thrombi:

  • CT angiography (useful for aortic mural thrombi) 2
  • Intravascular ultrasound (can guide treatment) 4

Management Approaches

Treatment depends on location and clinical context:

For Left Ventricular Thrombus:

• Anticoagulation: Primary treatment with vitamin K antagonists (target INR 2.0-3.0) for approximately 3 months
  • Reduces embolism risk by 86%
  • Results in thrombus resolution in 68% of cases 2

For Aortic Mural Thrombus:

• Anticoagulation: Historically first-line therapy but associated with:

  • 25-50% embolic recurrence rate
  • Thrombus persistence in 35% of cases
  • Need for secondary aortic surgery in up to 31% of cases 3

• Surgical intervention: Indicated for:

  • Mobile thrombus
  • Recurrent embolism
  • Contraindication to anticoagulation 3

• Endovascular coverage: When feasible, appears effective and safe with low recurrence and re-embolization rates 3

For Catheter-Related Thrombosis:

• Anticoagulation: Recommended for a minimum of 3 months

  • Low molecular weight heparins (LMWHs) are suggested
  • Vitamin K antagonists can also be used 1

• Catheter management: The catheter can be kept in place if it is:

  • Functional
  • Well-positioned
  • Non-infected
  • Shows good resolution under surveillance 1

Prevention Strategies

For catheter-related thrombosis prevention:

• Proper placement: Right-sided jugular vein insertion with catheter tip at the junction of superior vena cava and right atrium 1
• Catheter selection: Use catheters with minimal necessary lumens (thrombosis risk increases with number of lumens) 1
• Material selection: Less thrombogenic materials (silicone, second/third-generation polyurethane) 1
• Ultrasound guidance: Minimizes endothelial damage during placement 1

Risk Factors for Mural Thrombus Formation

• Anterior MI without reperfusion therapy (approximately one-third risk of apical thrombus) 2
• Severely reduced ejection fraction (<30%) 2
• Anterior MI with apex involvement (24% risk of apical thrombus by cardiac MRI) 2
• Chronic ventricular dysfunction from various etiologies 2
• Transient apical ballooning syndrome 2
• Prothrombotic disorders 3

Recognizing mural thrombus early and implementing appropriate management is crucial for preventing potentially life-threatening complications such as embolization, which can lead to significant morbidity and mortality.