Cardiothoracic Surgery: Aortic Stenosis (AS)

Aortic Stenosis (AS)

Basics

  • Definition: Stenosis & Narrowing of the Aortic Valve
  • Obstruction Causes Increased Afterload, Left Ventricular Wall Stress & Left Ventricular Hypertrophy
    • Increases Myocardial Oxygen Demand with Decreased Supply
  • The Most Common Valvular Lesion
  • More Common in Men & Elderly

Causes

  • Calcific Degeneration – Most Common Cause
  • Bicuspid Aortic Valve
  • Rheumatic Aortic Valve

Progression

  • 1/3 of Asymptomatic Patients with Severe Disease Will Become Symptomatic within 2 Years
  • Average Survival After Development of Symptoms: 2-3 Years

Presentation

  • Angina
  • Exertional Syncope
  • Congestive Heart Failure
  • Crescendo-Decrescendo Systolic Ejection Murmur
    • Heard Best at the Second Right Intercostal Space
    • May Radiate to the Carotid Arteries
  • *Symptoms are Uncommon Until Stenosis is Severe (Once Valve Area ≤ 1 cm2)

Diagnosis

  • Diagnosis: Echocardiogram
  • Severity:
Parameter Mild Moderate Severe
Aortic Valve Area 1.6-2.5 cm2 1.1-1.5 cm2 ≤ 1.0 cm2
Mean Pressure Gradient < 20 mmHg 20-39 mmHg ≥ 40 mmHg
Aortic Velocity (Vmax) 2.0-2.9 m/sec 3.0-3.9 m/sec ≥ 4.0 m/sec
  • Most Reliable Measure: Aortic Velocity
    • Normal Valve Area May Vary with Smaller Individuals
  • Stages:
    • Stage A: At Risk for AS
    • Stage B: Progressive (Mild-Moderate) AS
    • Stage C: Asymptomatic Severe AS
      • Stage C1: LV Ejection Fraction Normal (≥ 50%)
      • Stage C2: LV Ejection Fraction Reduced (< 50%)
    • Stage D: Symptomatic Severe AS

General Management

  • Asymptomatic: Monitoring for Disease Progression
    • Scheduled Echocardiogram:
      • Mild AS: Every 3-5 Years
      • Moderate AS: Every 1-2 Years
      • Severe AS: Every 6-12 Months
    • Statin Therapy Does Not Prevent Progression, Use for Coronary Artery Disease if Indicated
    • Treat Hypertension
  • Symptomatic: Aortic Valve Replacement (AVR)
    • TAVR/TAVI Generally Preferred
  • Indications for Palliative Care (Contraindication to AVR):
    • Estimated Life Expectancy < 12 Months Due to Noncardiac Comorbidities
    • Improvement in Quality of Life Unlikely Due to Comorbidities

Aortic Valve Replacement (AVR) Indications

  • Severe AS with Symptoms
  • Severe AS with Left Ventricular Systolic Dysfunction (EF < 50%)
  • Severe AS Undergoing Concomitant CABG, Heart Valve Surgery or Aortic Surgery
  • Class II Recommendations:
    • Very Severe AS with Low Surgical Risk
    • Severe AS with Exercise Testing Showing Decreased Exercise Tolerance
    • Moderate AS Undergoing Cardiac Surgery for Another Indication
    • Severe AS with Low Surgical Risk & Serial Testing Showing Increase in Aortic Velocity ≥ 0.3 m/s Per Year