Left Ventricular Aneurysm

Epidemiology

  • Association with Myocardial Infarction
    • Incidence: currently occurs in 8-15% of Q-wave myocardial infarctions (previously, incidence was as high as 30-35%)
      • Decreasing incidence is related to better care of acute myocardial infarctions
    • Risk Factors
      • Absence of Patent Infarct-Related Artery
      • Total Occlusion of Left Anterior Descending Artery

Etiology

  • Acute Myocardial Infarction (MI) (see Coronary Artery Disease, [[Coronary Artery Disease]])
  • Chagas’ Disease (see Chagas’ Disease, [[Chagas Disease]])
    • May result in formation of an apical aneurysm
  • Hypertrophic Cardiomyopathy (see Hypertrophic Cardiomyopathy, [[Hypertrophic Cardiomyopathy]])
    • May result in formation of an apical aneurysm

Physiology

Characteristics of Left Ventricular Aneurysm

  • Definition of Left Ventricular Aneurysm: well-demarcated and thin/fibrotic/scarred ventricular wall (usually the result of a prior trans-mural myocardial infarction with healing)
    • Aneurysm is Devoid of Muscle or Contains Necrotic Muscle
    • Aneurysmal Wall is Usually Thin and Consists of White, Fibrous Scar Tissue: endocardial surface is usually smooth and trabeculated
    • Aneurysm Contains Organized Thrombus in 50% of Cases: due to flow stasis within the aneurysm or contact of blood with procoagulant fibrous tissue within the aneurysm
      • Mural thrombus and/or aneurysmal wall may calcify over time
    • Dense Adhesions Commonly Develop Between the Aneurysmal Wall and the Adjacent Overlying Pericardium
    • Aneurysmal Wall is Either Akinetic (Lacking Movement) or Dyskinetic (with Paradoxical Ballooning) During Systole
    • Aneurysmal Wall Usually Collapses Inward with Venting During Surgery

Location of Left Ventricular Aneurysm

  • Location
    • Apical/Anterior Walls: 70-85% of cases (due to left anterior descending arterial occlusion)
    • Inferior/Basal Walls: 10-15% of cases (due to right coronary artery occlusion)
    • Lateral Wall: rare (due to left circumflex artery occlusion)
  • Left Ventricular Aneurysm in the Presence of Multi-Vessel Coronary Artery Disease: left ventricular aneurysm is uncommon if there is extensive collateralization or if the left anterior descending artery is patent

Size of Left Ventricular Aneurysm

  • Range: 1-8 cm

Risk of Left Ventricular Aneurysmal Rupture

  • Low: although left ventricular aneurysms may enlarge over time, they rarely rupture, due to the presence of dense fibrotic tissue within the aneurysmal wall
    • In contrast, left ventricular pseudoaneurysms (see Left Ventricular Pseudoaneurysm, [[Left Ventricular Pseudoaneurysm]]) have a high risk of rupture (30-45% of cases rupture)

Diagnosis


Clinical Manifestations

Cardiovascular Manifestations

  • Angina/Chest Pain (see Chest Pain, [[Chest Pain]]): due to increased left ventricular oxygen demand (which may result in myocardial ischemia, particularly in the setting of coronary artery disease)
  • Congestive Heart Failure (CHF) (see Congestive Heart Failure, [[Congestive Heart Failure]])
    • Physiology: systolic paradoxical bulging of the aneurysmal segment -> “loss” of part of the stroke volume, effectively decreasing cardiac output and causing left ventricular volume overload -> left ventricular dilates and wall stiffens -> increase in left ventricular end-diastolic pressure
      • Increased left ventricular size results in increased left ventricular wall tension -> increased left ventricular oxygen demand (which may result in myocardial ischemia, particularly in the setting of coronary artery disease)
  • Findings Related to the Left Ventricular Aneurysm Itself
    • Diffuse Apical Impulse with Displacement to the Left of the Mid-Clavicular Line
    • Palpable Dyskinesis Over Apex or Left Lateral Chest Wall in Region of the Left Ventricle Anterior Wall
    • Third/Fourth Heart Sound: often heard (due to blood flow into a dilated, stiff left ventricular chamber
    • Mitral Regurgitation Murmur (see Mitral Regurgitation, [[Mitral Regurgitation]]): due to distortion of left ventricular geometry with resulting absence of mitral valve leaflet apposition, papillary muscle dysfunction, and/or mitral annular dilatation
  • Ventricular Tachyarrhythmias: may result in sudden cardiac death
    • General Comments
      • Due to myocardial ischemia and increased myocardial stretch -> increased automaticity or triggered activity
      • Due to occurrence at reentrant tachycardia at the border zone in the myocardium (which consists of a mix of fibrotic tissue, inflammatory cells, damaged/disorganized muscle fibers): reentry may occur when two electrically heterogeneous pathways with distinct conduction velocities/refractoriness are adjacent to each other
    • Ventricular Tachycardia (VT) (see Ventricular Tachycardia, [[Ventricular Tachycardia]])
    • Ventricular Fibrillation (see Ventricular Fibrillation, [[Ventricular Fibrillation]])

Other Manifestations


Treatment

Medical Therapy

  • General Comments
    • 5-Year Survival with Medical Therapy: 90%
  • Afterload Reduction
  • Anti-Anginal Medications: as required
  • Anticoagulation: indicated for significant left ventricular dysfunction or with evidence of thrombus within the aneurysm or left ventricle (see Intracardiac Thrombus, [[Intracardiac Thrombus]])
    • Risk of Embolization Decreases with Chronicity of Left Ventricular Aneurysm: risk of embolization is low with aneurysms diagnosed at least a month after myocardial infarction (presumably due to endothelialization or organization of the thrombus), even though mural thrombus is frequently observed
      • Therefore, anticoagulation may not be required in these cases

Surgical Therapy

  • Indications for Surgical Repair
    • Congestive Heart Failure Unresponsive to Medical Therapy
    • Intractable Ventricular Arrhythmias Unresponsive to Catheter-Based Therapy
    • Progressive Increase in Left Ventricular Diameter and/or Decrease in Left Ventricular Ejection Fraction: even before the development of overt congestive heart failure
    • Refractory Angina
    • Symptomatic Patients with Akinetic/Dyskinetic Segments
    • Systemic Embolization in Patient with a Contraindication for Anticoagulation
  • Technique
    • Median Sternotomy
    • Left Lateral Thoracotomy

Prognosis

  • Coronary Artery Surgery Study (CASS) (1982): 71% 5-year survival
    • However, this and other studies of the long-term outcome of left ventricular aneurysm were performed prior to the modern era of acute myocardial infarction management and the results are likely not applicable to modern outcomes

References

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