4.1 Cardiac Glycosides

Question 1

Cardiac glycosides have what 2 effects on the heart?

Answer 1

Increase myocardial contractility AKA positive inotropic effect

Change the electrical conduction properties of the heart
- Decreased rate of electrical conduction
- Prolonged refractory period

Question 2

The refractory period is described as…

Answer 2

The period during which a pulse generator (SA node) is unresponsive to an electrical input signal, and during which it is impossible for the myocardium to respond.

During this period, the cardiac cell is readjusting its Na and K levels and cannot be depolarized again

Question 3

A short or nonexistant refractory period can cause what 3 things?

Answer 3

Atrial excitation
Atrial flutter
Atrial fibrillation

Question 4

Cardiac glycosides were originally obtained from which plant?

Answer 4

Digitalis purpurea or foxglove

Question 5

Cardiac glycosides were the mainly used drug for heart failure for more than ____ years

Answer 5

200

Question 6

Cardiac glycosides have which kind of inotropic, chronotropic, and dromotropic effects? Why?

Answer 6

Positive inotropic effect
- Increase force/velocity of myocardial contraction without an increase in

Negative chronotropic effect
- Reduce heart rate

Negative dromotropic effect
- Decrease automaticity at SA node – and AV node (decrease spontaneous depolarization)

Question 7

Cardiac glycosides have a ________ inotropic effect

Answer 7

Positive inotropic effect
- They increase the force/velocity of myocardial contraction without an increase in oxygen demand

Question 8

Cardiac glycosides have a ________ chronotropic effect

Answer 8

Negative chronotropic effect
- reduce heart rate

Question 9

Cardiac glycosides have a ________ dromotropic effect

Answer 9

Negative dromotropic effect
- Decreased automaticity at the SA node
- Decreased AV nodal conduction
- Reduced conductivity at the bundle of HIS
- Prolongation of refractory periods

Question 10

Stroke volume is…

Answer 10

the volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction

Question 11

Cardiac glycosides result in a(n) _____ stroke volume

Answer 11

increased

Question 12

Cardiac glycosides result in a(n) _________ in heart size

Answer 12

decrease

Question 13

Cardiac glycosides result in a(n) ________ in coronary circulation

Answer 13

increase

Question 14

How do cardiac glycosides affect urination?

Answer 14

Promotes diuresis due to improved blood circulation

Question 15

Indications for the use of cardiac glycosides include…

Answer 15

Heart failure

Supraventricular dysrhythmias (originates above the branching of AV node)

Other dysrhythmias (atrial fibrillation/flutter)

Question 16

T/F cardiac glycosides can be given to clients with 2nd or 3rd-degree heart block

Answer 16

False

Question 17

Drug levels of digoxin must be closely monitored for what reason?

Answer 17

It has a narrow therapeutic window

Question 18

Low levels of which electrolytes increases the toxicity of digoxin?

Answer 18

Potassium and magnesium

Question 19

What is the normal level for potassium?

Answer 19

3.5 - 5.5 mmol/L

Question 20

What is the normal level for sodium?

Answer 20

135 - 145mmol/l

Question 21

Normal therapeutic levels for digoxin are…

Answer 21

0.8 - 2 ng/mL

Reccomended is 0.5 - 0.9 ng/mL

Question 22

What are some adverse effects of digoxin on the cardiovascular system?

Answer 22

Dysrhythmias, including bradycardia or tachycardia

Question 23

What are some adverse effects of digoxin on the central nervous system?

Answer 23

Headaches, fatigue, malaise, confusion, convulsions

Question 24

What are some adverse effects of digoxin on the GI tract?

Answer 24

Anorexia, nausea, vomiting, diarrhea

Question 25

What are some adverse effects of digoxin on the ocular system?

Answer 25

Coloured vision – general tint, halo vision, flickering lights

Question 26

If the client experiences any adverse effects, you should…

Answer 26

hold the dose and notify the prescriber

Question 27

What is the first step in digoxin toxicity treatment?

Answer 27

Discontinue/hold the drug

Question 28

What is the second step in digoxin toxicity treatment?

Answer 28

ECG monitoring for dysrrhythmias

Question 29

What is the third step in digoxin toxicity treatment?

Answer 29

Determine serum digoxin and electrolytes levels

Question 30

What is the fourth step in digoxin toxicity treatment?

Answer 30

Administer K+ for hypokalemia

Question 31

What is the fifth step in digoxin toxicity treatment?

Answer 31

Supportive therapy for GI symptoms (nausea, vomiting, diarrhea)

Question 32

What is the sixth and final step in digoxin toxicity treatments?

Answer 32

Administer digoxin antidote –(digoxin immune Fab) ie: Digibind

Question 33

What should be assessed prior to administering positive inotropes?

Answer 33

• history
• drug allergies
• what drugs are they on
• contraindications

Question 34

What clinical parameters/baselines should be assessed prior to positive inotrope administration?

Answer 34

• BP
• Apical pulse for 1 full minute
• Heart sounds, breath sounds
• Weight
• I&O measures
• ECG
• Serum labs: potassium, sodium, magnesium, calcium, renal and liver function studies

Question 35

Before giving any dose of cardiac glycosides, you must…

Answer 35

Count the apical pulse for 1 full minute

Question 36

If the pulse is <____ or >____ bpm, hold and notify the prescriber

Answer 36

60, 120

Question 37

Avoid giving digoxin with which kinds food? Why?

Answer 37

Foods high in fibre. Fibre binds to digitalis

Question 38

Clients should report immediately a weight gain of ___ kg in ___ day or ____ or more kg in ____ week(s)

Answer 38

1 kg in 1 day

2.5 or more kg in 1 week