Electrocardiograph ECG waves and segments P wave QRS waveT wavePR interval QRS

Electrocardiograph ecg waves and segments p wave qrs

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Electrocardiograph ECG – waves and segments P- wave QRS – wave T- wave PR - interval QRS - interval QT- interval PQ – segment ST – segment SA node must depolarize Ventricular Depolarization QT intervial tells us about the action potential of the myocyte
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Summary
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Disorders Most problems caused by disjunction of electrical system Arrhythmia – abnormal cardiac rhythm 1. Heart Block (varies in degrees) – failure in conduction system 2. Atrial flutter – extra beats of the atrial muscle 3. Premature ventricular contractions (PVC’s) – extra beat 4. Ventricular fibrillation – electrical signals arrive at ventricular myocytes at different times 5. Myocardial infarction 6. Long QT 7. Electrolyte disturbances
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Heart Block – electrical signal disrupted between atria and ventricles i. First degree ii. Second degree iii. Third degree (complete) Disorders
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Electrocardiograph Nodal Rhythm – no SA node input , AV node pacemaker – 50 bpm Which wave is missing?
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Atrial Flutter: rapid heart beat (tachycardia) 250-300 bpm 2:1 QRS usually present (QRS max out at 250 bpm) Atrial Fibrillation: rapid heart beat (tachycardia) 300-500 bpm Disorders
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PVC’s (extrasystole) – usually originate in left ventricle i. Inverted, misshapen QRS wave Disorders
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Ventricular fibrillation– erratic firing of ventricular myocytes, unsynchronized contraction Disorders
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Myocardial Infarction (MI) i. ST elevation ii. T- wave inversion Disorders
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Long QT syndrome i. Ion channel mutations (K + , Ca 2+ , Na + ) ii. Leads to ventricular tachycardia, and death Disorders Longer to repolarize Na or Ca stays on K doesn’t turn on
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Changes in Plasma K + : most relevant electrolyte disturbance Disorders Hyperkalemia leads to death
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  • Spring '17
  • Cardiac electrophysiology, Sinoatrial node, ventricular tachycardia, Ventricular fibrillation, Cardiac Myocyte

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