Mitral Valve Function and Disorders

Function of the Mitral Valve

• One-way blood flow: Ensures blood flows from the left atrium to the left ventricle.
• Operation during cardiac cycle:
  • Diastole: Opens when left atrial pressure > left ventricular pressure, allowing blood to fill the left ventricle.
  • Systole: Closes when pressure gradient reverses, preventing backflow into the atrium.

Structure of the Mitral Valve

• Leaflets: Two flaps - anterior and posterior mitral leaflets.
• Support:
  • Mitral annulus: Fibrous ring supporting the leaflets.
  • Papillary muscles: Prevent incorrect opening direction.
  • Chordae tendineae: Tendinous chords attaching leaflets to papillary muscles.

Mitral Valve Prolapse (MVP)

• Description: Most common heart valve disease where mitral leaflets bulge into the left atrium during ventricular contraction.
• Causes:
  • Often unclear.
  • Linked to connective tissue disorders (e.g., Ehlers-Danlos, Marfan syndrome).
  • Weakened leaflets, increased leaflet area, elongation of chordae tendineae.
• Symptoms: Often asymptomatic but can increase risk of:
  • Arrhythmias
  • Endocarditis
  • Mitral valve regurgitation

Mitral Valve Regurgitation

• Cause: MVP is the most common cause.
• Mechanism:
  • Billowing leaflets may not fit properly.
  • Elongated chords may rupture.
  • Results in a leaky valve, allowing backflow into the left atrium during ventricular contraction.
• Consequences:
  • Volume overload on the left side of the heart.
  • Potential heart failure and pulmonary congestion.

Diagnosis and Treatment

• Diagnosis:
  • Auscultation: Abnormal heart sounds (clicks, murmurs).
  • Echocardiography: Visualizes heart valves and blood flow using ultrasound.
• Treatment:
  • Surgical repair:
    • Removing floppy valve portions.
    • Reconnecting remaining parts (annuloplasty).
  • Valve replacement: Considered when repair isn't possible.
    • Types of valves:
      • Mechanical: Long-lasting, requires lifelong anticoagulation therapy.
      • Bio-prosthetic.