Heart Failure

Question 1

When does heart failure occur?

Answer 1

when the CO is inadequate to provide the oxygen needed by the body

Question 2

Name the positive ionotropics

Answer 2

• Digoxin
• Bipyridines (Inamrinone, Milrinone)
• Beta-Adrenoceptor Agonists (Dobutamine)

Question 3

What effects does Digoxin have?

Answer 3

decrease the symptoms of heart failure, increase exercise tolerance, and decrease the rate of hospitalization, but does not increase survival

Question 4

What is the MOA of Digoxin?

Answer 4

 Digoxin binds to and inhibits the phosphorylated -subunit of the sarcolemmal Na+/K+ ATPase, the membrane-bound transporter protein also known as the ‘sodium pump’, leading to a decrease in Na+ extrusion and an increase in cytosolic Na+ levels

Question 5

What are the mechanical cardiac effects of Digoxin?

Answer 5

Increases the intensity of the actin and myosin filaments by increasing the free calcium concentration in the vicinity of the contractile proteins during systole

Question 6

What is the increase in calcium due to in the mechanical cardiac effects of Digoxin?

Answer 6

1. Increase in intracellular sodium concentration
2. Reduction in calcium expulsion from the cell by the sodium-calcium exchanger

Leading to an overal net result of increasing contractility

Question 7

What are the electrical cardiac effects of Digoxin?

Answer 7

Therapeutic concentrations cause a decrease in duration of cardiac action potential which decreases the atrial and ventricle refractory period (toxic concentrations reduce the RMP due to inhibition of the sodium, pump and reduced intracellular potassium along with calcium overload will lead to ectopic heartbeats/premature depolarization

Question 8

What can happen if premature depolarization is continued?

Answer 8

will lead to self-sustaining tachycardia which may deteriorate into fibrillation which can be fatal

Question 9

What effects does Digoxin have on other tissues?

Answer 9

All excitable tissues are affected by Digoxin including smooth muscle and the CNS
Inhibition of the sodium pump results in depolarization and increased spontaneous activity

Question 10

What toxicities does Digoxin have on the GIT?

Answer 10

• Anorexia

- N/V/D

Question 11

The _____ is the most common site of Digoxin toxicity outside the heart

Answer 11

GIT

Question 12

Name the CNS toxicities of Digoxin

Answer 12

• Disorientation
• Hallucinations
• Visual disturbances
• Convulsions

Question 13

What is a rare toxicity of Digoxin that is reported in men?

Answer 13

Gynecomastia

Question 14

What effects will hyperkalemia have with Digoxin?

Answer 14

interfere with Digoxin binding and will reduce its effects

Question 15

What effects will hypokalemia have with Digoxin?

Answer 15

stimulates Digoxin binding

Question 16

What effects will hypercalcemia have with Digoxin?

Answer 16

increases the risk of a Digoxin-induced arrhythmia

Question 17

What effects will hypomagnesemia have with Digoxin?

Answer 17

increases the risk of a Digoxin-induced arrhythmia

Question 18

Name the Bipyridines

Answer 18

Inamrinone

Milrinone

Question 19

What form are the bypyridines given in?

Answer 19

only IV

Question 20

What is the MOA of the bypyridines?

Answer 20

Selective PDE-3 inhibitors (found in the cardiac and smooth muscle) causing an increase in cAMP which leads to vasodilation and an increase in myocardial contractility due to calcium influx in the heart

Question 21

Name the toxicities of the bypyridines

Answer 21

• Arrhythmias
• Bone marrow toxicity (thrombocytopenia)
• Liver enzyme changes

Question 22

Which bypridine is less likely to cause bone marrow and liver toxicities?

Answer 22

Milrinone

Question 23

What is the Beta-adrenoceptor agonist?

Answer 23

Dobutamine

Question 24

Dobutamine is used in patients with ______ and ________

Answer 24

heart failure

chronic heart failure

Question 25

What is the MOA of dobutamine?

Answer 25

Selective beta-1 agonist which will increase cAMP levels causing an increase in CO and a decrease in ventricular filling pressure

Question 26

Name the toxicites of dobutamine

Answer 26

• Tachycardia

- Increase in myocardial oxygen consumption which can lead to angina or arrythmias

Question 27

Name the negative ionotropics

Answer 27

• Diuretics
• ACE Inhibitors
• ARBs
• Vasodilators
• Beta-blockers

Question 28

What effects do diuretics have?

Answer 28

Reduce venous pressure and ventricular preload causing a reduction in edema and cardiac size which will improve pump efficiency

Question 29

What effect do aldosterone antagonists have on diuretics?

Answer 29

decrease morbidity and mortality due to aldosterone causing myocardial and vascular fibrosis and baroreceptor dysfunction

Question 30

What effects do ACEs and ARBs have?

Answer 30

• Reduce PVR thus reducing afterload
• Reduction in salt and water retention by reducing aldosterone secretion thus reducing preload
• Reduction in angiotensin levels decreases sympathetic activity by decreasing NE release
• Reduction in the long-term remodeling of the heart and vessels

Question 31

What effect do vasodilators have?

Answer 31

Effective in acute HF due to reduction in preload via venodilation or a reduction in afterload via arteriolar dilation or both

Question 32

Long-term use of vasodilators may __________ remodeling of the heart

Answer 32

reduce

Question 33

What effects do beta-blockers have?

Answer 33

• Reduce mortality especially with Bisoprolol, Carvedilol, and Metoprolol in patients with severe HF
• Cause reduced adverse effects of the catecholamines, up-regulation or beta receptors, decreased heart rate, and reduced remodeling