Medications Affecting Cardiac Rhythm

Question 1

What is the mechanism of action for class 1 andtidysrhythmics?

Answer 1

inhibit sodium from entering the cell; this changes the rate of repolarization.

Question 2

What is the mechanism of action for class 2 antidysrhythmics?

Answer 2

blocks beta receptors in the heart causing a decrease in heart rate, conduction, and contractility

Question 3

What is the mechanism of action for class 3 antidysrhythmics?

Answer 3

blocks potassium channels; prolongs repolarization

CAN BE PROARRHYTHMIC

Question 4

What is the mechanism of acton for class 4 antidysrhythmics?

Answer 4

blocks calcium from entering the cell; this decreases the rate and conduction, as well as depresses depolarization

Question 5

What is the absolute refractory period?

Answer 5

a time in action potential when new depolarization cant occur

Question 6

What is relative refractory period?

Answer 6

a time in action potential when depolarization can occur but may be abnormal

Question 7

What is diminished refractory period?

Answer 7

depolarization can occur and will be normal.

Question 8

What does class 1a do, what do they treat?

Answer 8

blocks sodium channels and delays repolarization (PO or IV)

atrial and ventricular

Question 9

What does class 1b and 1c do?

Answer 9

accelerates repolarization

1b: atrial and ventricular (PO or IV)
1c: atrial rhythms only (PO only)

Question 10

What are some adverse effects of class 1a?

Answer 10

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

Question 11

What are some adverse effects of class 1b?

Answer 11

CNS effects (lidocaine toxicity): drowsiness, altered mental status, paresthesias, seizures– monitor

Respiratory arrest: monitor vitals

Question 12

What are some adverse effects of class 1c?

Answer 12

bradycardia: monitor ECG

Heart failure: monitor for chest pain or edema

Question 13

What do we do if any of the adverse effects occur with antidysrhythmics?

Answer 13

STOP administration and call the physician.

Question 14

What is the therapeutic action of class 2 antidysrhythmics? What rhythms do they treat?

Answer 14

blocks sympathetic nervous system stimulation to cause a decrease in HR and slow conduction

atrial and ventricular

REVIEW ADVERSE EFFECTS OF BETA BLOCKERS

Question 15

What do we check before administration of class 2 as well?

Answer 15

blood Pressure

also can mask symptoms of hypoglycemia (beta 1)

beta 2 antagonist can cause bronchoconstriction and hypoglycemia

Question 16

What is the mechanism of action for class 3 antidysrhythmics? What rhythms?

Answer 16

blocks potassium channels which prolongs the ABSOLUTE refractory period of repolarization; also decreases automaticity and contractility

atrial and ventricular dysrhythmias

Question 17

Can class 3 be proarrhythmic?

Answer 17

YES YES YES

Question 18

What are some adverse effects of class 3?

Answer 18

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

Question 19

What drink should be avoided with class 3?

Answer 19

GRAPEFRUIT JUICE

Question 20

what is the therapeutic action of class IV? What rhythms?

Answer 20

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)

Question 21

What drink should be avoided with class IV?

Answer 21

GRAPEFRUIT JUICE

Question 22

what is the therapeutic action of adenosine?

Answer 22

decreases the electrical conduction through the AV node

causes a momentary block in the AV node (asystole)

used for atrial dysrhythmias (SVT)

Question 23

Does adenosines effects last long?

Answer 23

NO NO NO

Question 24

What does adenosine essentially do to the heart?

Answer 24

Basically stops it so it can restart

Question 25

How is adenosine administered?

Answer 25

Its given very rapidly IV push (1-2 seconds), if it is given correctly it will pause the rhythm