Drugs for Heart Failure 2

Question 1

What is the effect of beta blockers?

Answer 1

• reduces heart rate and oxygen consumption
• cardiac output is increased after several months
• chance of irregular heart beat reduced
• mortality reduced post MI-> treatment of choice post-infarct

Question 2

What are the benefits of beta-adrenergic receptor blockade?

Answer 2

• decrease adverse effects of high catecholamine levels on the heart
• decreased cardiomyocyte apoptosis (cell death)
• decreased cardiac remodelling (decreased mitogenic activity)
• — mechanism is not completely understood

Question 3

Describe the action of carvedilol?

Answer 3

• blocks beta and alpha adrenergic receptors
• alpha adrenergic receptor blockade helps to relax (dilate) arteries
• the heart does not have to work as hard to eject blood (decreased after load)
• beta adrenergic receptor blockade slows the heart and decreases force of contraction
• first line treatment in heart failure

Question 4

What is the main difference between metoprolol and carvedilol?

Answer 4

– metoprolol selectively blocks beta 1 adrenergic receptors

Question 5

Beta blockers should be avoided in what conditions?

Answer 5

• avoid in asthma, COPD, peripheral vascular disease, insulin dependent diabetes, physically active

Question 6

What diseases are beta blockers mostly used in?

Answer 6

• hypertension
• glaucoma
• certain arrhythmia
• MI
• angina

Question 7

What is the drug interaction between carvedilol and ventolin?

Answer 7

• interaction with ventolin worsens breathing problems due to a narrowing of the airways

Question 8

What is the interaction between carvedilol/metoprolol and verapamil?

Answer 8

interaction can cause an irregular heart beat

Question 9

Antiretroviral medications can cause an _____

Answer 9

arrhythmia

Question 10

Why is alcohol dangerous to take with blood pressure lowering agents?

Answer 10

• has an additive effect on lowering blood pressure

Question 11

What is the action of ionotropes?

Answer 11

• alter the force of contraction of the heart (increase contraction)
• positive ionotropes are of interest here

Question 12

What is the effect of long term use of ionotropes?

Answer 12

• increased mortality

Question 13

What are the 2 examples of ionotropes?

Answer 13

-digoxin and dobutamine

Question 14

Explain the mechanism of action of dobutamine?

Answer 14

• must be given via IV
• stimulates beta adrenergic receptors in the heart to increase heart rate and more importantly contractility
• must carefully monitor- may increase heart rate, myocardial oxygen consumption and blood pressure
• may aggravate ischemia and promote arrhythmias

Question 15

Explain the mechanism of digoxin?

Answer 15

• increases heart contractility (increases calcium release in myocardial cells)
• blocks Na/K ATPase
• must closely monitor (can increase heart rate, myocardial O2 consumption, BP. Can also aggravate schema and provoke arrhythmias)

Question 16

What is the symptomatic improvement that digoxin provides?

Answer 16

• improved exercise capacity and decreased hospitalization for heart failure

Question 17

When taking digoxin, it is important to monitor ____ levels

Answer 17

potassium

(hypokalemia increases digoxin toxicity, as both inhibit the Na/K ATPase

Question 18

What drugs must you be careful with when giving digoxin?

Answer 18

• diuretics: may produce hypokalemia (increases digoxin toxicity)
• ACEIs/ARBs or B-adrenegric receptor antagonists: may increase potassium levels
• Potassium sparing diuretics: do not cause hypokalemia, not as good at increasing sodium excretion
• interactions with some medications can dangerously increase blood levels of digoxin resulting in cardiac arrhythmias (antibiotics such as amoxicillin and erythromycin, amiodarone)

Question 19

What is the action of the proximal tubule of the kidney?

Answer 19

• reabsorbs almost all glucose and amino acids and about 60% of sodium
• Na is reabsorbed through a Na/K ATPase
• CL exchanged for formate or oxalate anions
• water follows passively to maintain osmolarity

Question 20

What ist he action of the ascending loop of henle?

Answer 20

• impermeable to water

- Na/K/2Cl co-transporter reabsorbs 30% of these ions

Question 21

What is the action of the collecting tubule and duct?

Answer 21

• reabsorbs Na and water from the urine and secretes K

- Na/K ATPast is performing this function

Question 22

What is the primary site of action of thiazide diuretics?

Answer 22

distal tubule

Question 23

What happens in the distal tubule when a thiazide diuretic is added as a treatment option?

Answer 23

• inhibition of the Na/Cl transporter
• decreasing Na/Cl reabsorption (increase in Na excretion)
• increase in Ca reabsorption (decrease in Ca excretion)

Question 24

What are the main problems associated with thiazide diuretics?

Answer 24

• hypokalemia- increased Na in urine at distal tubule causes more K to be exchanged for Na causing loss of K from the body
• hyperglycemia - problem for type 2 diabetes (decreases insulin release, decreases tissue utilization)
• increase in LDL levels
• increased incidence of erectile dysfunction
• volume contraction
• interaction with the anti-arrhythmic agent amiodarone can lead to a more irregular heartbeat

Question 25

What are the advantages of using a thiazide diuretic over other medications to treat blood pressure?

Answer 25

- orally active - no postural hypertension - potentiate other anti-hypertensives

Question 26

What do thiazide diuretics do to K? Uric acid? BP? Na? Ca?

Answer 26

K: due to increased aldosterone - sodium reabsorption at expense of potassium loss Uric acid: increases BP: decreses Na: lowers due to the direct effect to increase sodium excretion Ca: due to direct effect to decrease calcium excretion

Question 27

What is the mechanism of action of loop diuretics?

Answer 27

- inhibit the Na/K/2Cl co-transporter in the ascending loop of henle - very potent and efficacious- high ceiling diuretics. Up to 20% of the filtered load if excreted - prostaglandins are very important - useful in acute pulmonary edema - increases Na, Cl, K, Mg and Ca excretion (note Ca effect)

Question 28

The effect on ___ is opposite in loop diuretics and thiazide diuretics?

Answer 28

calcium

Question 29

What are the main side effects of loop diuretics?

Answer 29

- deafness and kidney damage - never combine loop diuretics with amino glycoside antibiotics - interaction with the antiarrhythmatic agent amiodarone can lead to a more irregular heartbeat

Question 30

When are loop diuretics typically used?

Answer 30

- preferred in renal insufficiency - glomerular filtration rate of under 50 ml/min - edema, hypertension, hypercalcemia, heart failure

Question 31

Describe potassium sparing diuretics?

Answer 31

- weak diuretics - give with other diuretics to decrease potassium loss - may cause hyperkalemia - never combine with K supplements

Question 32

Describe the action of spironolactone

Answer 32

- aldosterone receptor antagonists - prevents aldosterone from binding to the receptor (decreases sodium reabsorption, decreases potassium excretion) - may cause hyperkalemia - prevents cardiac remodeling associated with high levels of aldosterone in heart failure

Question 33

How potassium sparing diuretics manage ___ is opposite of loop and thiazide diuretics

Answer 33

K

Question 34

What are the steps of managing a patient with heart failure?

Answer 34

- managing conditions that contribute to heart failure (hypertension, diabetes, lipids) - diet physical activity and lifestyle changes 1. start with ACEI or Beta-adrenegeric receptor blockade (lowers bp and reduces stress on the heart) 2. Diuretic- in patients with edema (remove excess fluids and sodium from the body) 3. Extreme failure- add an ionotrope (increases contractility to alleviate heart failure symptoms)

Question 35

Beta blockers are only started once patients are _____ on ACEI- should start at a low dose

Answer 35

stable

Question 36

Describe the different stages of heart failure (A-D)

Answer 36

A: High risk heart failure with no symptoms B: Structural heart disease, no symptoms C: structural heart disease, previous or current symptoms Stage D: end stage-just trying to improve quality of life