CHAPTER 36 .pdf - JORGE LOPEZ 36 DYSRHYTHMIAS Properties of...

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JORGE LOPEZ 36 DYSRHYTHMIAS Properties of Cardiac Cells Automaticity: Ability to initiate an impulse spontaneously and continuously Excitability: Ability to be electrically stimulated Conductivity: Ability to transmit an impulse along a membrane in an orderly manner Contractility: Ability to respond mechanically to an impulse Nervous System Control of Heart Autonomic nervous system controls Parasympathetic nervous system Decreases rate of SA node Slows impulse conduction of AV node Sympathetic nervous system Increases rate of SA node Increases impulse conduction of AV node Increases cardiac contractility Dysrhythmias Disorder of impulse formation, conduction of impulses, or both SA node normal pacemaker of heart (60–100 beats/minute) Secondary pacemakers AV node (40–60 beats/minute) His-Purkinje fibers (20–40 beats/minute) Electrocardiogram Monitoring Graphic tracing of electrical impulses produced by heart Waveforms of ECG represent activity of charged ions across membranes of myocardial cells
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Calculating HR Count Number of QRS complexes in 1 minute R-R intervals in 6 seconds, and multiply by 10 Number of small squares between one R-R interval, and divide this number into 1500 Number of large squares between one R-R interval, and divide this number into 300 Assessment of Cardiac Rhythm Patient Preparation Clip excessive hair on chest wall Rub skin with dry gauze May need to use alcohol for oily skin Apply electrode pad Artifact
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Telemetry Monitoring Observation of HR and rhythm at a distant site Two types Centralized monitoring system Advanced alarm system alerts when it detects dysrhythmias, ischemia, or infarction Assessment of Cardiac Rhythm Interpret the rhythm AND evaluate the clinical status of the patient UAP can apply leads for ECG Nurse responsible to verify placement & analyze rhythm Is the patient hemodynamically stable? Determine cause of dysrhythmia Treat the patient, not the monitor! Assessment of Cardiac Rhythm 1. P wave: atrial depolarization 2. Atrial rate and rhythm 3. P-R interval 0.12 – 0.20 sec & constant 4. Ventricular rate and rhythm 5. QRS complex 6. ST segment 7. Q-T interval 8. T wave Normal Sinus Rhythm Sinus node fires 60–100 beats/minute Follows normal conduction pattern SINUS BRADYCARDIA: < 60 BPM Normal rhythm in aerobically trained athletes and during sleep Can occur in response to parasympathetic nerve stimulation and certain drugs Also associated with some disease states
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Sinus Bradycardia <60 regular Normal for Hypothermia Increased IOP Vagal stimulation Athletes Parasympathetic NS Diseases Increased ICP Hypoglycemia Inferior MI Manifestations Hypotension Pale, cool skin Weakness Angina Dizziness or syncope Confusion or disorientation Shortness of breath Treatment Atropine: anticholinergic
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  • Spring '17
  • Acevedo
  • Cardiology, Cardiac electrophysiology, ventricular tachycardia

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