Exam 2 Antidysrhythmic Meds Flashcards
Automaticity (vocab)
Hearts ability to generate an electrical impulse.
Conductivity (vocab)
Ability of cardiac tissue to transmit electrical impulses.
Cardiac Action Potential (Patho)
Action potentials are generated by movement of ions into and out of the cell
Two types of action potentials in the heart:
Fast
Myocardium and His-Purkinje system
Conduct electricity quickly through the heart
Slow
SA and AV nodes
Differences in which ions impact each phase of the action potential
Formation of dysrhythmias (Patho)
Disturbances of automaticity
Cells other than the SA node depolarize and initiate an electrical impulse which causes a contraction
Can result in:
Tachydysrhythmias
Bradydysrhythmias
Area creating these impulses is called ectopic
Disturbances of conduction Changes in electrical flow through the normal pathway in the heart Can result in: Atrioventricular block Reentry pathways
Ectopic (vocab)
When the heart either skips a beat or adds an extra beat
Common dysrhythmias
Type of dysrhythmia divided based on location:
Supraventricular
Ventricular
Ventricular dysrhythmias more dangerous
Treatment includes 2 phases:
Termination of the dysrhythmia acutely
Long-term suppression of the dysrhythmia
Supraventricular dysrhythmias
Different types:
Supraventricular tachycardia
Atrial fibrillation
Atrial flutter
Less dangerous than ventricular dysrhythmias
No in cardiac output
Dangerous if:
Electrical impulses cross the AV node
↑ ventricular rate
GOAL:
Decrease impulse transmission through the AV node to decrease ventricular rate
Supraventricular tachycardia
Tachydysrhytmias
HR:>150 beats/min
Intervention:
Valsalva: forceful attempted exhalation against a closed airway, usually done by closing one’s mouth and pinching one’s nose shut while expelling air out as if blowing up a balloon.
Cardio version: shock/cpr
Atrial Fibrillation
Tachydysrhytmia
No coordinated atrial contraction
Stroke risk
Intervention:
Cardio version
Drug therapy:
Adenosine
Class II or IV
Atrial Flutter
Tachydysrhythmia
Coordinated atrial contraction
Stroke risk
Intervention:
Cardio version
Class II or IV drugs
Anticoagulation
Ventricular Dysrhythmias
Sustained ventricular tachycardia
Ventricular fibrillation
Torsades de pointes
Dangerous because these impact cardiac pumping and cardiac output
GOAL:
Abolish the dysrhythmia
First-line therapy typically cardioversion
Drugs are second-line
Classification of antidysrhythmic drugs
4 major classes Class I: Sodium Channel Blockers Class II: Beta-blockers Class III: Potassium Channel Blockers Class IV: Calcium Channel Blockers Other: digoxin and adenosine
General Principles of Antidysrhythmic Agents
All antidysrhythmic drugs can also cause dysrhythmias
Balance risk and benefit
Only use when benefit outweighs risk
Type of dysrhythmia is the patient experiencing
Phases of treatment
Long term treatment: Drug selection and evaluation
Minimizing risks
Start with low doses
Monitor drug levels if indicated
Class I: Sodium Channel Blockers
Drugs: Class IA Disopyramide Quinidine Procainamide
Class IB Lidocaine Mexiletine Class IC Flecainide Propafenone
Acronym Double Quarter Pounder Lettuce Mayo Fries Please
Class I: Sodium Channel Blockers
Effects are secondary to sodium channel blockade
↓ conduction velocity in the atria, ventricles and His-Purkinje system
Divided into 3 subtypes
Similar in action and structure to local anesthetics