Lecture on Atrial Fibrillation (AF)

Heart Anatomy

• The heart contains four chambers:
  • Upper Chambers: Right and Left Atrium
  • Lower Chambers: Right and Left Ventricles

Fibrillation

• Fibrillation refers to muscle fibers contracting at different times, causing a quivering or twitching movement.
• Normal process:
  • Electrical signal from sinus node (right atrium) propagates through atria, causing coordinated contraction.
  • Signal moves to ventricles for contraction.
• Atrial Fibrillation (AF):
  • Signals in atria become disorganized, overriding the sinus node.
  • Result in mini contractions, making atria appear to quiver on an ECG.

ECG Observations

• Normal ECG: P wave (atrial contraction), followed by QRS complex (ventricular contraction).
• AF ECG: Irregular, scribbled pattern due to uncoordinated atrial contractions.
  • Irregular QRS complexes at high rates (100-175 bpm).

Atrial Kick

• Normally contributes a small amount of blood from the atrial contraction.
• Lost in AF, not life-threatening but reduces efficiency.

Causes and Risk Factors of AF

• Often associated with cardiovascular diseases:
  • High blood pressure, coronary artery disease, valvular diseases.
• Non-cardiovascular factors:
  • Obesity, diabetes, excessive alcohol consumption.
• Genetic predispositions.
• Tissue heterogeneity and multiple wavelet theory.
  • Different electrical properties lead to unpredictable atrial conduction.

Types and Progression of AF

• Paroxysmal AF: Sudden, short episodes.
• Persistent AF: Lasts more than a week without self-termination.
• Long-standing Persistent AF: Lasts beyond 12 months.
• Permanent AF: Decision made not to terminate the rhythm.

Symptoms and Complications

• Symptoms: Fatigue, dizziness, shortness of breath, weakness, palpitations.
• Complications:
  • Increased risk of stroke due to potential blood clot formation.

Diagnosis

• Persistent AF diagnosed by ECG.
• Paroxysmal AF might require Holter monitor for extended monitoring.

Treatment Options

• Depends on individual issues:
  • Medications to control heart rate and reduce clot risk.
  • Implantable cardiac pacemaker.
  • Radiofrequency catheter ablation to destroy problematic tissues.
  • Maze procedure to create new electrical pathways.
  • AV node ablation with pacemaker for ventricular control.