Medications Affecting Cardiac Rhythm Flashcards
What is the mechanism of action for class 1 andtidysrhythmics?
inhibit sodium from entering the cell; this changes the rate of repolarization.
What is the mechanism of action for class 2 antidysrhythmics?
blocks beta receptors in the heart causing a decrease in heart rate, conduction, and contractility
What is the mechanism of action for class 3 antidysrhythmics?
blocks potassium channels; prolongs repolarization
CAN BE PROARRHYTHMIC
What is the mechanism of acton for class 4 antidysrhythmics?
blocks calcium from entering the cell; this decreases the rate and conduction, as well as depresses depolarization
What is the absolute refractory period?
a time in action potential when new depolarization cant occur
What is relative refractory period?
a time in action potential when depolarization can occur but may be abnormal
What is diminished refractory period?
depolarization can occur and will be normal.
What does class 1a do, what do they treat?
blocks sodium channels and delays repolarization (PO or IV)
atrial and ventricular
What does class 1b and 1c do?
accelerates repolarization
1b: atrial and ventricular (PO or IV)
1c: atrial rhythms only (PO only)
What are some adverse effects of class 1a?
widening of the QRS complex (if widened more than 50% could become proarrhythmic)/ closelsy monitor ECG
Hypotension - monitor BP
neutropenia and thrombocytopenia: monitor CBC for first 12 weeks
What are some adverse effects of class 1b?
CNS effects (lidocaine toxicity): drowsiness, altered mental status, paresthesias, seizures– monitor
Respiratory arrest: monitor vitals
What are some adverse effects of class 1c?
bradycardia: monitor ECG
Heart failure: monitor for chest pain or edema
What do we do if any of the adverse effects occur with antidysrhythmics?
STOP administration and call the physician.
What is the therapeutic action of class 2 antidysrhythmics? What rhythms do they treat?
blocks sympathetic nervous system stimulation to cause a decrease in HR and slow conduction
atrial and ventricular
REVIEW ADVERSE EFFECTS OF BETA BLOCKERS
What do we check before administration of class 2 as well?
blood Pressure
also can mask symptoms of hypoglycemia (beta 1)
beta 2 antagonist can cause bronchoconstriction and hypoglycemia
What is the mechanism of action for class 3 antidysrhythmics? What rhythms?
blocks potassium channels which prolongs the ABSOLUTE refractory period of repolarization; also decreases automaticity and contractility
atrial and ventricular dysrhythmias
Can class 3 be proarrhythmic?
YES YES YES
What are some adverse effects of class 3?
Pulmonary toxicity (very dangerous) - monitor pulmonary function
sinus brady, AV blocks, v-tach (proarrhythmic) - monitor BP and ECG
Heart failure (cardiotoxicity): monitor signs of heart failure
Phlebitis with IV: use central line
What drink should be avoided with class 3?
GRAPEFRUIT JUICE
what is the therapeutic action of class IV? What rhythms?
Blocks calcium channels causing a decrease in the force of contraction, HR, and slows conduction
used for atrial dysrhythmias
REVIEW ADVERSE EFFECTS FOR CALCIUM CHANNEL BLOCKERS (monitor BP because of vasodilation, monitor for bradycardia, look for signs of heart failure)
What drink should be avoided with class IV?
GRAPEFRUIT JUICE
what is the therapeutic action of adenosine?
decreases the electrical conduction through the AV node
causes a momentary block in the AV node (asystole)
used for atrial dysrhythmias (SVT)
Does adenosines effects last long?
NO NO NO
What does adenosine essentially do to the heart?
Basically stops it so it can restart
How is adenosine administered?
Its given very rapidly IV push (1-2 seconds), if it is given correctly it will pause the rhythm
