Cardiac Glycosides

Question 1

Define what Congestive Heart Failure is:

Answer 1

Inability of the heart to provide the necessary output.

Question 2

List the sequence of events for congestive heart failure:

Answer 2

1. Decreased cardiac output
   
   2. Decreased peripheral bloodflow (anoxia)
   3. Decreased renal bloodflow = increased renin production, increased angiotensin, increased aldosterone
   4. Increased salt, increased ADH = water retention
      
      5. Increased venous pressure = EDEMA

Question 3

What occurs when there is insufficient blood flow that further complicates congestive heart failure?

Answer 3

• Reflex Sympathetic output
  
  1. Increases heart rate
  2. Increases peripheral resistance
     
     3. Increases oxygen demand

Question 4

Why are the reflex sympathetic output events undesired effects in CHF?

Answer 4

Increases burden on the heart

Question 5

What is the target of drug therapy for CHF?

Answer 5

Block the sympathetic nervous system!

Question 6

Causes of CHF?

Answer 6

1. Atherosclerotic coronary artery disease
   
   2. Myocardial infarction
   3. Myocarditis, various cardiomyopathies, valvular and congenital defects
   4. Aortic stenosis
   5. Systemic hypertension
      
      6. Diet, humidity, exertion, anemia, infection

Question 7

Name the acute symptoms of CHF

Answer 7

1. Tachycardia
   
   2. Shortness of breath
   3. Edema
      
      4. Decreased exercise tolerance

Question 8

Chronic symptoms of CHF

Answer 8

1. Various arrhythmias
   
   2. Hypertension (increased peripheral resistance)
   3. Cardiomegaly
      
      4. Edema

Question 9

Symptoms of Left Side Heart Failure:

Answer 9

1. Reduced cardiac output
   
   2. Reduced blood pressure
   3. Pulmonary congestion
      
      • *More acute in nature

Question 10

Which side of the heart in heart failure has symptoms more acute in nature?

Answer 10

Left Side Heart Failure

Question 11

Name the 6 goals of treatment for CHF

Answer 11

1. Slow heart rate to increase the filling time
   
   2. Increase contractile force to improve the ejection fraction (make heart more efficient)
   3. Increase cardiac output
   4. Reduce retention of salt and water
   5. Decrease angiotensin-induced increase in peripheral resistance (block angiotensin to decrease peripheral resistance)
      
      6. Decrease sympathetic nervous system

Question 12

What is the drug category of choice for CHF?

Answer 12

Cardiac Glycosides

Question 13

Name the preparations of Cardiac Glycosides

Answer 13

**digoxin (Digitek, Lanoxin)

Question 14

Digoxin is metabolized by what organ of the body?

Answer 14

Kidney

Question 15

Indications for digoxin

Answer 15

1. CHF

2. Atrial fibrillation/flutter

Question 16

What is the general mechanism of action and effects of cardiac glycosides?

Answer 16

1. Inhibits Na/K ATPase pump
   
   2. Directly suppresses AV node conduction to increase ERP and decrease conduction velocity
      
      3. Causes diuresis

Question 17

Explain the effects of the inhibition of Na/K ATPase pump in the action of cardiac glycosides

Answer 17

• This results in increased Ca+ inside of cell
  - Increases contraction of the heart
  - Positive inotropic effect

Question 18

What are the effects of suppressing the AV node conduction in cardiac glycosides?

Answer 18

• Slows down repolarization of myocytes following action potentials
  
  • This results in prolonged action potential
• **Slows heart rate = negative chronotropic effect

Question 19

Name the diuretic effects that cardiac glycosides cause:

Answer 19

1. Decreases venous return
   
   2. Allows heart to become more efficient
   3. Decreases filling pressure
   4. Decreases heart rate
      
      5. Decreases heart size

Question 20

What are the problems with cardiac glycosides?

Answer 20

1. Increased vagal ouput = can be blocked by atropine (anticholinergic drug)
   
   2. Slowing of AV conduction = can slow too much which allows for ectopic foci = uncoordinated arrhythmias** can arise
   3. Low therapeutic index = therapeutic dose is approximately 50-60% of the toxic dose
      
      • Every patient must be titrated

Question 21

List the general digoxin toxicities:

Answer 21

1. Block conduction between SA node and AV node
   
   2. GI effects result from stimulation of chemoreceptor zones and vagal nucleus (parasympathetic effects)
      
      3. Various CNS effects

Question 22

Describe more in depth what happens when Digoxin blocks conduction between SA node and AV node

Answer 22

1. Bradycardia occurs because of the lack of conduction (AV block)
   a. Because slows heart so much, heart betas before it is full (decreased CO)
   
   2. Since conduction is blocked between upper and lower part of the heart, the lower part of the heart may start beating on its own (extra beats = extrasystoles)
      
      3. **Causes Arrhythmias

Question 23

List the GI effects that result from digoxin toxicity

Answer 23

1. Nausea/vomiting
   
   2. Increase in salivation
   3. Anorexia
   4. Diarrhea
      
      5. Abdominal pain

Question 24

List the CNS effects of digioxin toxicity

Answer 24

1. Headache = vasodilation, changes in edema in CNS
   
   2. Fatigue = decreased muscle tone (Parasympathetic effect makes you feel fatigue)
   3. Drowsiness
   4. Visual disturbances (blurry)
      
      5. Green/yellowiah aura = patient knows that he is at toxic level of digitalis if he sees this aura

Question 25

What are the treatment scenarios for digoxin toxicity

Answer 25

1. Discontinue drug
   
   2. Give antidoe = digoxin immune fab (Digibind, DigiFab)
      a. Antibodies bind with digoxin which are then excreted via urine
      
      3. Administer Potassium chloride and anti-arrhythmic medications

Question 26

Decreased intraceullular levels of what ion potentiates the effects of digitalis?

Answer 26

• K+ (potassium)
• Increasing K+ will decrease the effects of digitalis and is a reason why potassium chloride is used as a treatment of Digoxin Toxicity

Question 27

The level of digoxin may be increased by concurrent use of what drugs?

Answer 27

- The red flag drugs in dentistry
		○ *systemic azole antifungals
		○ *macrolide antibiotics
		○ This increased risk for toxicity
        - Caution with vasoconstrictors - risk for arrhythmias

Question 28

Know the red flag drugs in dentistry:

Answer 28

• Systemic azole antifungals

- Macrolide antibiotics

Question 29

In summary, what does Digoxin do?

Answer 29

• Decreases heart rate which increases filling time

- Increases force of contraction so that it can increase ejection fraction

Question 30

Other than Cardiac Glycosides, what drugs might be helpful for CHF?

Answer 30

1. ACE inhibitors
   
   2. B1 agonists = increase force of contraction to increase cardiac output
      
      3. Vasodilators = decrease preload/afterload; decrease filling pressure and work of the heart

Question 31

5 dental considerations for a patient on cardiac glycosides

Answer 31

1. Decrease stress for the patient
   
   2. Caution with use of local anesthetics with vasoconstrictors
   3. Avoid using gingival retraction cords due to potency of vasoconstrictors
   4. Do not recline patient fully: hard to breathe
      
      5. General anesthesia decreases cardiac output and decreases perfusion = dangerous to a patient with CHF

Question 32

Symptoms of Right Sided Heart Failure

Answer 32

1. Fatigue (muscles deprived of oxygen)
   
   2. Dyspnea
      
      3. Edema