Lecture on Cardiac Conduction System Issues

Overview of Conduction System Problems

• SA Node Issues

  • Bradycardia: Slow heart rate due to SA node firing too slowly.
  • Tachycardia: High heart rate due to SA node firing too quickly.

• Damage to SA Node or Internodal Pathways

  • AV node can act as a backup pacemaker.
  • AV node fires at 40-60 BPM, often too low for normal heart rate.
  • Known as a conduction deficit.

Ectopic Pacemakers

• Definition: Electrical impulses generated outside of SA or AV nodes.
• Causes:
  • Abnormal conducting cells firing their own impulses.
  • Contractile cells in the ventricle firing impulses.
• Effect: Disrupts normal timing by interfering with SA and AV node activity.

Artificial Pacemakers

• Used when the SA node is malfunctioning or ectopic pacemakers are present.
• Function: Small electrical device implanted in the chest wall.
  • Fires electrical impulses to stimulate heart contractions.

Arrhythmias

• Definition: Irregular heart rhythm or force of heartbeat.
• Diagnosed using ECGs.

Common Type: Ventricular Fibrillation

• Characteristics:
  • Abnormal electrical activity in ventricles.
  • Causes heart muscle to quiver, preventing effective pumping.
  • ECG appears irregular and abnormal.
• Analogy: Normal heartbeat like pebble ripples in a lake; V-fib like many pebbles thrown.

Treatment for Ventricular Fibrillation

• Defibrillation:
  • Uses drugs or strong electrical current to reset conduction system.
  • Automated External Defibrillators (AEDs) can be used by anyone following instructions.
  • Effectiveness varies; quicker use increases survival chances.