Cardiac Physiology

Normal Cardiac Cycle

CARDIAC CYCLE


Normal Heart Sounds

  • S1
  • S2

Normal Cardiac Conduction

Cardiac Conduction System

CARDIAC CONDUCTION

Electrical Correlates of the Normal EKG (see Electrocardiogram, [[Electrocardiogram]])

  • PR Interval
    • Depolarization of Atrium (P-Wave)
    • Conduction Through AV Node
    • Conduction Through His Bundle
    • Conduction Through Bundle Branches
    • Conduction Through Fascicles
    • Conduction Through Terminal Purkinje Fibers
  • QRS
    • Ventricular Depolarization
  • T-Wave
    • Ventricular Repolarization

Blood Supply to the Cardiac Conduction System

  • Blood Supply to the Sinoatrial (SA) Node
    • Right Coronary Artery: 60% of patients
    • Left Circumflex Artery: 40% of patients
  • Blood Supply to the Atrioventricular (AV) Node
    • Right Coronary Artery: 90% of patients
    • Left Circumflex Artery: 10% of patients
  • Blood Supply to the His Bundle
    • Right Coronary Artery: main blood supply
    • Septal Perforators of the Left Anterior Descending Coronary Artery: minor contribution
  • Main/Proximal Left Bundle Branch
    • Left Anterior Descending Artery: main blood supply
    • Right Coronary Artery: collateral flow
    • Left Circumflex Artery: collateral flow
  • Left Anterior Fascicle
    • Septal Perforators of the Left Anterior Descending Coronary Artery: main blood supply
    • AV Nodal Artery: 50% of patients
  • Left Posterior Fascicle
    • Proximal Left Posterior Fascicle
      • AV Nodal Artery: main blood supply
      • Septal Perforators of the Left Anterior Descending Coronary Artery: in some cases
    • Distal Left Posterior Fascicle
      • Anterior and Posterior Septal Perforating Arteries (Dual Blood Supply)
  • Right Bundle Branch
    • Septal Perforators of the Left Anterior Descending Artery: main blood supply
    • Right Coronary Artery: some collateral flow (depending on dominance of the system)
    • Left Circumflex Artery: some collateral flow (depending on dominance of the system)

References

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