Anti arrhythmic agents chapter 45 Flashcards
Describe the automaticity, excitability , conductivity, contractility of the cardiac muscle s
-Automaticity – cells can spontaneously initiate impulse or action potential – pacemaker cells
-Excitability – ion shift – ability to respond to impulse and generate action potential
-Conductivity – able to transmit impulse
-Contractility – how well cell contracts after receiving a stimulus
** Injured/ scarred cells lose excitability **
What is the normal functioning conductivity
Impulse starts in SA node
Transmitted to AV node
Down bundle of His
Purkinje fibers
What is arrhythmias? and what can cause them
Arrhythmias involve changes of rate and rhythm due to automaticity or conduction abnormalities
Causes:
Electrolyte imbalance – Ca, K, Na, Mg
Hypoxia
Structural damage that alters conduction pathway
Acidosis/waste accumulation – renal failure
Other cardiac drugs – pro-arrhythmic
What is the goal of anti-arrhythmic drugs?
Alter heart’s electrical conduction system
Mechanism of action is to reduce automaticity, slow conduction and prolong refractory period( cant respond to any new stimuli)
Goal is to prevent arrhythmias, relieve symptoms, and prolong life
What are indications of anti-arrhythmic drugs?
atrial fibrillation and atrial flutter
decrease ventricular rate and irregularity
may also be used for HTN control
What are different classes of anti-arrhythmic drugs?
Class I – Sodium channel blockers
**lidocaine (Xylocaine)
Class II – Beta blockers
**metoprolol (Lopressor)
Class III – Potassium channel blockers
**amiodarone (Cordarone)
Class IV – Calcium channel blockers
**diltiazam (Cardizem)
What are different classes of sodium channel blockers?
anti-arrhythmic
Class 1a- procainamide (Pronestyl)
Class 1b- **lidocaine (Xylocaine)
Class 1c- flecainide (Tambocor)
What is the therapeutic action of lidocaine (Xylocaine)?
anti-arrhythmic, Class 1b
-Block the movement of sodium into cells of cardiac conduction system
-Slows conduction, prolongs refractory period, decreases automaticity, stabilizes cell membrane
Class Ib drugs depress phase 0 somewhat and shorten the duration of the action potential.
What are the indications of lidocaine (Xylocaine)?
anti-arrhythmic, Class 1b
used for ventricular arrhythmias
Atrial fibrillation, premature atrial & ventricular contractions (PAC’s & PVC’s), V tach
What are the pharmokinetics of lidocaine (Xylocaine)?
anti-arrhythmic, Class 1b
Given IV due to extensive first pass effect, dose reduce with renal dz and rapid onset
Decreases myocardial irritability
What are the adverse effects of lidocaine (Xylocaine)?
anti-arrhythmic, Class 1b
CNS effects – tremors, seizures,dizziness,fatigue
GI effects – n/v, change in taste
CV effects – pro-arrhythmic effects, hypotension, vasodilation, potential for cardiac arrest
What are contras of lidocaine (Xylocaine)?
anti-arrhythmic, Class 1b
Heart block, hypotension, shock
-allergy
What are drug to drug interactions of lidocaine (Xylocaine)?
anti-arrhythmic, Class 1b
Potentiates oral anti-coagulants( increased risk for bleeding )
What is class ll anti-arrythmic?
Beta blockers
What is metoprolol (Lopressor)?
Beta blocker class ll
What are therapeutic actions of metoprolol (Lopressor)?
Beta blocker class ll
Beta blockers inhibit SNS stimulation
decreases rate and contraction
decreases BP, decreases O2 demand
What are indications of metoprolol (Lopressor)?
Beta blocker class ll
Rate control, HTN, acute MI, angina prevention, a-fib, a-flutter
What are adverse effects of metoprolol (Lopressor)?
Beta blocker classll
r/t blocking SNS
-Constricted pupils
-Stimulate salvation
-slow hr
-vasodilation
-constrict airways
-stimulate stomach/intestines activities
-contract bladder
Barely proarrythmic so no
What are contras of metoprolol (Lopressor)?
Beta blocker class ll
Bradycardia, heart block, asthma, copd andy respiratory distress
What are cautions of metoprolol (Lopressor)?
Beta blocker class ll
Diabetes-can mask signs of hypoglycemia
Hypothyroidism
Hepatic/renal dysfunction
What are drug to drug interactions with metoprolol (Lopressor)?
Beta blocker class ll
Caution with use of additional cardiac meds
What are class lll
Potassium Channel Blockers
What is amiodarone (Cordarone)?
Class III – Potassium Channel Blockers
What is therapeutic action of amiodarone (Cordarone)?
Class III – Potassium Channel Blockers
Prolongs action potential and refractory period by blocking the cardiac potassium channels – vasodilate effect
What is indications of amiodarone (Cordarone)?
Class III – Potassium Channel Blockers
Used for ventricular irritability, V-tach and V-fib, atrial irritability
What is adverse effects of amiodarone (Cordarone)?
Class III – Potassium Channel Blockers
Arrhythmias
Liver toxicity
Ocular abnormalities(white halo)
Pulmonary toxixicty
What is contras of amiodarone (Cordarone)?
Class III – Potassium Channel Blockers
None when used to treat life threatening incidents
What is cautions of amiodarone (Cordarone)?
Class III – Potassium Channel Blockers
Long QT
renal/hepatic disease
What are drug to drug interactions of amiodarone (Cordarone)?
Class III – Potassium Channel Blockers
TCAs, anti-histamines
increased risk of proarrhythmias if they are combined with antihistamines, phenothiazines, or tricyclic antidepressants
What is diltiazem (Cardizem) ?
Class IV – Calcium Channel Blockers
What are therapeutic actions of diltiazem (Cardizem) ?
Class IV – Calcium Channel Blockers
Inhibit movement of calcium ions across myocardial/ arterial muscle cells which:
slows cardiac impulse
causes vasodilation
reduction of blood pressure
decrease of venous return
delaying phases 1 and 2 of repolarization, which slows automaticity and conduction. Electrical activity through the SA and AV nodes is partially dependent on the calcium influx, so the medications slow AV conduction and ventricular rate
What are indications of diltiazem (Cardizem)?
Class IV – Calcium Channel Blockers
Used for a-fib, a-flutter, SVT
HTN and treat angina (dilt specific
What are adverse affects of diltiazem (Cardizem)?
Class IV – Calcium Channel Blockers
CNS weakness, dizziness, fatigue
GI upset, N/V
CV hypotension, arrhythmias
What are contras of diltiazem (Cardizem)?
Class IV – Calcium Channel Blockers
Heart block could be exacerbated
pregnancy, grapefruit juice can potentiate
What are cautions of diltiazem (Cardizem)?
renal or hepatic dysfunction
Use with other cardiac meds
What are other drugs for arrhymias?
**adenosine (Adenocard)
**digoxin (Lanoxin)
Describe **adenosine (Adenocard)
used for SVT slows conduction through AV node
short duration of action (10-15 seconds)
Describe **digoxin (Lanoxin)
Slows conduction and heart rate
Good for atrial arrhythmias
What to asses with anti-arrhythmic agents
Allergies
VS, Neuro status
Physical assessment
Close attention to cardiac status
Past medical history
Labs; Baseline ECG
What are nursing diagnosis with anti-arrhythmic agents?
Decreased cardiac output r/t cardiac effects of medication
Risk for injury r/t adverse drug effects
Decreased cardiac output r/t cardiac effects of medication
Risk for injury r/t adverse drug effects
What is implementation with anti arrhythmic agents
Monitor for med-induced arrhythmias
Continuous cardiac monitoring
Assess for CNS effects
Safety measures/ Fall prevention
Administration
ALWAYS assess VS before administering
Educate patient on self-management
Whats evaluation for ant-arrhythmic agents?
Monitor pt response (stabilization of cardiac rhythm)
