More Related Content
Similar to Ppt chapter 45
Similar to Ppt chapter 45 (20)
More from stanbridge (20)
Ppt chapter 45
- 1. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Antiarrhythmic Agents
Chapter 45
- 2. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Conducting System of the Heart
- 3. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Five Phases of the Action Potential of the
Cardiac Muscle Cell
• Phase 0: Occurs when the cell reaches a point of
stimulation
• Phase 1: Short period during which the sodium ion
concentration equalizes inside and outside of the cell
• Phase 2 (Plateau Stage): Occurs as the cell membrane
becomes less permeable to sodium, calcium slowly enters
the cell, and potassium begins to leave the cell
- 4. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Five Phases of the Action Potential
of the Cardiac Muscle Cell (cont.)
• Phase 3: A time of rapid repolarization as the sodium
gates are closed and potassium flows out of the cell
• Phase 4: The cell comes to rest; the sodium–potassium
pump returns the membrane to its resting membrane
potential, and spontaneous depolarization begins again
- 5. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Cardiac Arrhythmias
• Tachycardia (faster-than-normal heart rate)
• Bradycardia (slower-than-normal heart rate)
• Premature atrial contractions (PACs) or premature
ventricular contractions (PVCs)
• Atrial flutter
• Atrial fibrillation or ventricular fibrillation
• Alterations in conduction through the muscle (heart
blocks and bundle branch blocks)
- 6. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Causes of Cardiac Arrhythmias
• Electrolyte disturbances that alter the action potential
• Decreases in oxygen delivered to the cells
• Structural damage changing the conduction pathway
through the heart
• Acidosis or accumulation of waste products altering the
action potential
• Drugs that alter the action potential or cardiac conduction
- 7. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Classifications of Antiarrhythmics
• Class I: Block the sodium channels in the cell membrane
during an action potential
• Class II: Block beta-receptors, causing a depression of
phase 4 of the action potential
• Class III: Block potassium channels, prolong phase 3 of
the action potential
• Class IV: Block calcium channels in the cell membrane
- 8. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cardiac Action Potentials
- 9. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Please answer the following statement as true or false.
One cause of cardiac arrhythmias is a decrease in oxygen
delivered to the cells.
- 10. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
True
Rationale: Causes of cardiac arrhythmias include:
electrolyte disturbances that alter the action potential;
decreases in oxygen delivered to the cells; structural
damage changing the conduction pathway through the
heart; acidosis or accumulation of waste products
altering the action potential and drugs that alter the
action potential or cardiac conduction
- 11. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Sub-Classes of Class I Antiarrhythmic
Drugs
• Class Ia: Depress phase 0 of the action potential and
prolong the action potential duration
• Class Ib: Depress phase 0 somewhat and actually
shorten the duration of the action potential
• Class Ic: Markedly depress phase 0, with a resultant
extreme slowing of conduction
- 12. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class I Antiarrhythmic
• Actions
– Decreases depolarization, decreasing automaticity of the
ventricular cells; increases ventricular fibrillation threshold
• Indications
– Management of acute ventricular arrhythmias during
cardiac surgery or MI
• Pharmacokinetics
– Widely distributed after injection or after rapid absorption
through GI tract
– Hepatic metabolism and excreted in the urine
- 13. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class I Antiarrhythmic (cont.)
• Contraindications
– Allergy, bradycardia or heart block, CHF, hypotension
or shock, electrolyte disturbances
• Caution
– Renal or hepatic dysfunction or pregnancy
• Adverse Effects
– CNS effects: Dizziness, fatigue, slurred speech
– GI – Nausea and vomiting
– CV – Arrhythmias
- 14. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class I Antiarrhythmic (cont.)
• Adverse Effects (cont.)
– Respiratory depression
– Misc. – Rash, loss of hair, and potential bone marrow
suppression
• Drug-to-Drug Interactions
- 15. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class II Antiarrhythmic
• Actions
– Competitively block beta receptor sites in the heart
and kidneys
– Decrease heart rate, cardiac excitability, and cardiac
output
– Slow conduction though the AV node
• Indications
– Treatment of supraventricular tachycardia and PVCs
- 16. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class II Antiarrhythmic (cont.)
• Pharmacokinetics
– Absorbed from GI tract and undergo hepatic
metabolism, excreted in the urine
• Contraindications
– Sinus bradycardia, AV block, cardiogenic shock, CHF,
asthma, or respiratory depression, pregnancy, and
lactation
• Caution
– Diabetes, thyroid dysfunction, renal or hepatic
dysfunction
- 17. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class II Antiarrhythmic (cont.)
• Adverse Effects
– Related to the effects of blocking beta receptors in the
sympathetic nervous system
– CNS – Dizziness, insomnia, dreams, and fatigue
– CV – Hypotension, bradycardia, AV block, arrhythmias
– Respiratory – Bronchospasm and dyspnea
– GI – Nausea, vomiting, anorexia
– Misc. – Loss of libido, decreased exercise tolerance,
alterations in blood glucose levels
• Drug-to-Drug Interactions
– Verapamil
- 18. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class III Antiarrhythmic
• Actions
– Block potassium channels and slow the outward movement of potassium
during phase 3 of the action potential
– This action prolongs the action potential
• Indications
– Life-threatening ventricular arrhythmias
– Maintenance of sinus rhythm after conversion of atrial arrhythmias
• Pharmacokinetics
– Absorbed and widely distributed, metabolized in the liver and excreted in
the kidneys
• Contraindications
– When used for life-threatening arrhythmias there is no contraindication
- 19. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class III Antiarrhythmic (cont.)
• Caution
– Shock, hypotension, respiratory depression,
prolonged QT interval, renal or hepatic disease
• Adverse Effects
– Nausea, vomiting, weakness, dizziness, arrhythmia
• Drug-to-Drug Interactions
– Digoxin or Quinidine
– Other specific drug interactions vary with individual
drugs
- 20. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class IV Antiarrhythmic
• Actions
– Block the movement of calcium ions across the cell
membrane
– Depressing the generation of action potential
– Delaying phases 1 and 2 of repolarization
– Slow conduction through the AV node
• Indications
– Supraventricular tachycardia
– Control the ventricular response to rapid atrial rates
- 21. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class IV Antiarrhythmic (cont.)
• Pharmacokinetics
– Well absorbed, protein bound, metabolized in the
liver, and excreted in urine
• Contraindications
– Allergy, sick sinus syndrome or heart block,
pregnancy, lactation, CHF, hypotension
• Caution
– Idiopathic hypertrophic subaortic stenosis
- 22. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Class IV Antiarrhythmic (cont.)
• Adverse Effects
– Dizziness, weakness, fatigue, depression, GI upset,
hypotension, CHF, and shock
• Drug-to-Drug Interactions
– Many drug-to-drug interactions
- 23. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Which of the following is an adverse effect of the class II
antiarrhythmics?
A. Bronchospasm
B. Flatus
C. Colitis
D. Centralized edema
- 24. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
A. Bronchospasm
Rationale: Adverse effects that involve the respiratory
system include bronchospasm and dyspnea
- 25. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Other Drugs Used to Treat Arrhythmias
• Adenosine (Adenocard)
– Used to convert supraventricular tachycardia to sinus
rhythm when vagal maneuvers have been ineffective
• Digoxin
– Slows calcium from leaving the cell, prolonging the
action potential and slowing conduction and heart
rate
- 26. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Use of Antiarrhythmic Across
the Lifespan
- 27. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prototype Class I Antiarrhythmic
- 28. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prototype Class II Antiarrhythmic
- 29. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prototype Class II Antiarrhythmic
(Continued)
- 30. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prototype Class III Antiarrhythmic
- 31. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prototype Class III Antiarrhythmic
(Continued)
- 32. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prototype Class IV Antiarrhythmic
- 33. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Prototype Class IV Antiarrhythmic
(Continued)
- 34. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nursing Considerations for Antiarrhythmic
Therapy
• Assessment: History and Physical Exam
• Nursing Diagnosis
• Implementation
• Evaluation