❤️ Chapter 17 Module 16 Atrial Fibrillation (AF) – Cardiac Arrhythmia Module

 

Atrial fibrillation (AF or AFib) is a common heart rhythm disorder where the atria (upper chambers of the heart) beat in a rapid, irregular, and uncoordinated way. Instead of contracting properly, they quiver (fibrillate).

It is strongly associated with:

• Increased risk of stroke (4–5 times higher)
• Increased risk of death (about 2 times higher)
• Age-related cardiovascular disease

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⚙️ Pathophysiology

In AFib:

• Electrical signals in the atria become chaotic
• Atria lose effective contraction
• This leads to loss of the “atrial kick”

🫀 Atrial Kick Loss

Normally, atrial contraction adds 20–30% extra blood volume into the ventricles.
When this is lost:

• Cardiac output decreases
• Stroke volume decreases

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⚠️ Cardiac Effects

• Blood pools in the atria (stasis)
• Risk of blood clot (thrombus) formation increases
• Clots may travel to the brain → stroke risk

🔥 AF with RVR (Rapid Ventricular Response)

• Heart rate >100 bpm (often >150 bpm)
• Can cause dizziness, chest pain, or collapse

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📊 ECG Findings

• Irregularly irregular rhythm
• No clear P waves
• Fibrillatory baseline activity
• Variable QRS timing

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🧪 Diagnosis

• ECG (primary diagnostic tool)
• Echocardiogram (heart structure check)
• TEE (Transesophageal Echocardiogram):
  • Used to detect clots before cardioversion
• Risk scoring system:
  • CHA₂DS₂-VASc score → estimates stroke risk

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💊 Management and Treatment

AFib treatment focuses on 3 main goals:

1. 🧠 Stroke Prevention

• Anticoagulants:
  • Warfarin
  • NOACs (e.g. apixaban, rivaroxaban)

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2. ❤️ Rate or Rhythm Control

Rate control:

• Slows heart rate without fixing rhythm

Rhythm control:

• Restores normal sinus rhythm

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3. ⚡ Procedures

• Cardioversion
  • Synchronized electrical shock (~150 joules)
• Catheter ablation
  • Destroys abnormal electrical pathways

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📌 Key Terms

• Arrhythmia: Abnormal heart rhythm
• Atrial kick: Final atrial contraction that fills ventricles
• Thrombus: Blood clot formed inside a vessel or heart

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⚠️ Complications

• Stroke (most serious risk)
• Heart failure (reduced output over time)
• Chronic fatigue and reduced exercise tolerance
• Embolic events (clots travelling through bloodstream)

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📌 Key Summary

• AFib is a chaotic atrial rhythm disorder
• Leads to poor cardiac efficiency and blood pooling
• Major complication = stroke risk from clot formation
• Managed with:
  • Anticoagulation
  • Rate/rhythm control
  • Procedures like cardioversion or ablation