Heart Rhythms: Normal or Abnormal (Arrhythmias) Anatomy & Physiology L2 and L3

Cardiac Muscle 

Electrical Conduction  SA Node  Primary “jump- start” for the heart  Creates a beat approx 70 bpm  If faulty, replaced by artificial pacemaker  AV node  Delays/ ↓ transmission of signal  Could only create approx 40 bpm on its own  NOT strong enough to sustain life (so need the SA node)

Interior anatomy of heart  Bundle of His  Collection of cardiac cells creating the AV bundle  Conduct impulses along septum to the Purkinje fibers in walls of the ventricles  Takes impulse about sec to travel to the ventricles  Purkinje fibers: largest fibers filaments  Located on inner wall of endocardium  Carry electrical impulse from SA and AV nodes

Electrocardiogram (ECG or EKG)  12-lead (multi- angle)

Normal Sinus Rhythm  P wave  QRS complex  T wave

Bradycardia

Tachycardia  Notice the sinus rhythm  Approx 120 bpm

Ventricular Fibrillation  Overall: 300 bpm  Cannot sustain life

Artificial Pacemakers  Implanted beneath skin  Composed of: electrical pulse generator and lead wires to communicate with the heart tissue  Permanent battery  Can be checked over the phone

Pacemakers