1
Q
Define heart failure
A
- the inability of the heart to pump enough blood to satisfy the body’s demand for oxygen
- failure to pump enough blood may be due to any disorder that interferes with the heart’s ability to receive or eject blood
- often have decreased myocardial contractility/stroke volume and decreased cardiac output
2
Q
What are the main risk factors of heart failure?
A
- cardiovascular disease, previous MI, chronic HTN, and T2 DM
- mitral stenosis, cardiomyopathies and congenital heart disease may also predispose individuals to HF
3
Q
What causes patients in HF to have increased preload?
A
- increased preload results from an increase in blood volume (RAA pathway –> fluid retention)
- increased preload can also be caused by an increase in venous pressure (due to decreased venous compliance) or - increased ventricular compliance
4
Q
Is increased preload more likely to cause left or right-sided heart failure?
A
left sided HF
5
Q
What is the main consequence of left sided heart failure?
A
- blood backs up into the pulmonary system (a consequence of increased preload)
- the fluid leaves the pulmonary capillaries and goes into the alveoli and interstitium of the lung causing edema
6
Q
Why is having fluid collect in the lungs a concern? How is this condition connected to the term “congestive” heart failure?
A
- fluid buildup in the lungs reduces the ability of the alveoli to engage in gas exchange and results in decreased oxygen supply and the characteristic SOB
- fluid collection in the lungs is the cause of congestion and SOB and is the “congestive” component referred to in CHF
7
Q
Why is increased workload a common symptom of HF?
A
Decreased contractility and cardiac output result in lower BP.
8
Q
What system/pathway does the body activate and what hormone is released because of the low BP? How does this activation and hormone release increase BP (general answer)?
A
- low BP results in less blood flow to the kidneys so the RAA system is activated
- ADH is released from the posterior pituitary to conserve water
- blood volume increases through water and Na+ retention by the kidneys
9
Q
How does the body’s response to the low BP make the heart failure worse?
A
- water retention increases peripheral resistance which increases afterload
- the increased afterload causes the blood to back up into the peripheral circulation resulting in edema (legs, ankles)
- this puts greater workload on the cardiac muscle which worsens HF
10
Q
CAD, HTN, and DM can remodel the myocardial tissue making it compensate for having to work harder to supply the body with sufficient oxygen. What does this compensation often result in?
(hint: ventricular thickening…)
A
- the walls of the ventricular chamber may grow thicker and loose elasticity, which affects its ability to expand and pump effectively
- the extra thickness in the walls is also harmful bc the added tissue further increases the demand for oxygen
11
Q
What is more common, failure of the left ventricle or the right ventricle?
A
left sided HF
12
Q
What is the consequence of left sided HF?
A
Failure of the left side causes fluid build-up in the lungs and leads to difficulty breathing
13
Q
What is the consequence of right sided HF?
A
- Right sided HF causes the blood to work up into the peripheral veins and result in edema in the lower limbs and engorgement of organs like the liver
- often results in jugular vein distention
- right sided HF can be caused by lung disease
14
Q
What is cardiac output?
A
Cardiac output is the product of stroke volume multiplied by the number of beats per minute
15
Q
What controls stroke volume?
A
- how much blood is able to flow into the heart and fill the ventricles
- how well the heart contracts to eject this blood
16
Q
T or F: Reduce stroke volume can be a consequence of systolic dysfunction, diastolic dysfunction or a combination of both
A
TRUE
17
Q
What is the Frank-Starling mechanism?
A
- the greater end-diastolic volume results in a more forceful contraction due to stretch of ventricles
- the greater the preload, the greater the stroke volume
18
Q
T or F: Decreased cardiac output is a consequence of HF and it results from only systolic dysfunction
A
FALSE! Decreased cardiac output can result from either systolic or diastolic dysfunction
19
Q
What is diastolic dysfunction? Which two things are affected in diastolic dysfunction?
A
- conditions which adversely affect ventricular filling and stroke volume are referred to as diastolic dysfunctions
20
Q
How does ventricle filling decrease?(reduced lusitropy)
A
- the incomplete relaxation by the damaged muscle tissue lessens the capacity of the ventricle
- this results in a reduced preload
21
Q
When there is damage to the heart (ie. HTN), the heart muscles die and become stiff, unable to contract. The healthy tissue that is left has to contract that much harder to move blood, resulting in hypertrophy.
How do these changes affect ventricular function and consequently, stroke volume?
A
The ventricles will not be able to stretch as much due to the thickening and stiffening of the muscle walls which will reduce stroke volume
reduced stroke volume = diastolic dysfunction
22
Q
Decreased stroke volume leads to decreased ______________ _______________. (hint: CO = SV x HR)
A
decreased cardiac output
- this results in decreased perfusion of tissues and organs
23
Q
What is systolic dysfunction?
A
- the impaired contractility of the heart (often due to loss of muscle tissue due to MI or alterations in cellular signal transduction mechanisms)
- the heart muscle is weak and can’t squeeze enough blood out to the body (decreased stroke volume)
24
Q
What are two ways that the body compensates for decreased contractility?
A
- increases muscle mass causing hypertrophy or it dilates to allow a greater amount of blood into the chamber
- increases preload through the RAA pathway (increased blood volume)
25
What is another way that preload is increased in systolic dysfunction?
- preload is increased due to increased end-diastolic volume
- ex: if 75 mls would normally be ejected and now only 50 mls is ejected, 25 mls are left in the ventricle and added to the venous return volume
- increased end-diastolic volume increases workload
26
What is ejection fraction?
- value measured using an echocardiogram and used to gauge the severity of HF
- ejection fraction = (stroke volume / end-diastolic volume) x 100
27
What are some symptoms of HF?
- dyspnea
- orthopnea
- fatigue
- weakness
- exercise intolerance
- cough
- dependent edema
- cough
- weight gain
- abdominal distention
- nocturia
28
T or F: The body's attempt to compensate for HF usually worsens the condition
true
29
How do adrenergic blockers help treat heart failure?
- block sympathetic nervous system
- lower BP and reduce HR
- reduction in BP reduces workload by decreasing afterload and making it easier for the heart to pump blood to body
- ex: carvedilol, eprosartan, irbesartan, valsartan
- side effects: caution of masked hypoglycemia in diabetic pts
30
What is the mechanism of action of propranolol, a beta1/2 receptor blocker?
- blocks beta 1 receptors, the G protein cascade stops, Ca+ channel closes and intracellular calcium flows back into storage = muscle relaxation
- leads to vessel vasodilation, lowering BP, slowing HR and decreasing cardiac output
- propranolol also depresses RAA system resulting in less fluid retention and lowering of BP
31
How do vasodilators help treat heart failure?
- decrease peripheral resistance, reduce afterload and increase stroke volume and cardiac output
- ex: hydralazine with isosorbide dinitrate
32
What is the specific mechanism of action of isosorbide dinitrate, a vasodilator?
- long-acting organic nitrate that reduces preload by directly dilating veins and reducing venous pressure
- reduced venous pressure decreases proximal capillary fluid filtration and edema formation
- combined with hydralazine bc the two drugs act synergistically to decrease cardiac workload
33
How do ACE inhibitors help treat heart failure?
- ACE inhibitors reduce BP and decrease cardiac workload
- ex: lisinopril (also reduced fluid retention via inhibition of RAA pathway)
- Side Effects: dysgeusia, chronic cough)
34
How do phosphodiesterase inhibitors help treat heart failure?
- increase contractility in the heart and therefore stroke volume
- ex: milrinone
35
What is significant about the use of milrinon, a phosphodiesterase inhibitor?
- milrinone is fast acting and administered IV in crisis situations
- constant monitoring on ECG is required
- used on short-term basis and has short half-life of 2.3 hrs
36
How do cardiac glycosides help treat HF?
- used when other drugs are not accomplishing symptom reduction
- slows heart and increases the force of contraction
- acts on Na/K pump
- ex: digoxin (narrow margin between therapeutic and toxic dose)
37
What is the mechanism of action of digoxin, a cardiac glycoside?
- digoxin inhibits the sodium/potassium ATPase transport system leading to a loss of potassium from the heart cells and an increase of sodium in heart cells
- increased sodium activates the Na+/Ca+; increase in intracellular calcium enhances myocardial contraction
- this causes more force to be generated w/o increased oxygen consumption
- digoxin also slows the heart rate which allows more filling of the heart and improves cardiac output
- increases stroke volume, decreased preload, and increases ejection fraction
38
How do diuretics help treat HF?
- increase urine output which lowers blood volume and therefore preload and cardiac workload
- ex: furosemide (lasix)
39
What are the three types of diuretics and examples of each?
1. Loop (high ceiling)
- bumetanide
- furosemide
2. Thiazide / Thiazide-like
- hydrocholorthiazide
3. Potassium-sparing
- spirononlactone
- triamterene
40
Which medication is first-line treatment for HF? Which medication is often added to the first-line therapy?
- ACE inhibitor
| - beta-blockers are often added in after initiation of ACE inhibitor
41
If a pt can't tolerate the cough that can be caused by the ACE, what medication can they be prescribed instead?
- ARBs or a combination of nitrates and hydralazine
42
What lifestyle modifications can help "manage" HF?
- healthier diet (reduction in salt)
- increase exercise (after taking a stress test)
- fluid restriction
43
What is one way to monitor dosage effectiveness?
keeping track of weight measurements, along with periodic measurement of BP
44
If lifestyle modifications and ACE inhibitor/beta-blockers don't help alleviate symptoms, what may nee to be prescribed?
- angiotension receptor blocker
- digoxin (cardiac glycosides) w/ or w/o nitrates
- additional diuretics
45
What does the nurse need to monitor when a pt is prescribed diuretic therapy?
- weight gain
- K+ levels
- electrolytes
- blood sugar
46
What does the nurse need to monitor when a pt is prescribed an ACE inhibitor or ARB therapy?
- regular blood counts to monitor for neutropenia
- monitor K+ and Na+ levels (hyponatremia and hyperkalemia may result)
- hypotension
- lower doses in elderly/renal insufficiency
47
Which patient populations need to be monitored closing if prescribed beta blockers?
- diabetics
| - pts with hepatic impairment
48
What does the nurse need to monitor when a pt is prescribed an isosorbide dinitrate?
- contraindicated with viagra due to severe hypotension
| - commonly combined with hydralazine in ACE inhibitor intolerance
49
What does the nurse need to monitor when a pt is prescribed cardiac glycoside therapy?
- digoxin antibody may need to be administered if dysrhythmia occurs
50
What is the compensatory mechanism for decreased contractility and cardiac output?
- HR rises (reflex tachycardia) and this increases the workload placed on the heart
51
Which controls heart rate and does it decrease or increase with age?
SA node and decreases
52
Uncommon symptoms of heart failure
```
Cognitive impairment
Altered mentation or delirium
- Result of poor blood flow to brain
- More often seen with advancing age
Nausea, abdominal discomfort, and anorexia
- Caused by additional fluid in abdomen
- Feel bloated, full, or uncomfortable
Oliguria
- Decreased urine output
- Suggestive of renal failure
- Must be treated before normally excreted compounds build up to toxic levels in blood
Cyanosis- Result of poor circulation → inadequate oxygenation of tissues
```
PHARMACOLOGY
flashcards
Decks in class (27)
# Cards
-
01- Drug Administration and Absorption55
-
02- Drug Distribution, Metabolism and elimination43
-
03- Development of Dosage Regimen27
-
04- Potency, Efficacy and Therapeutic Index47
-
06-Cellular Reception and Drug Action54
-
05- Medication Safety67
-
07- Drugs for pituitary, thyroid and adrenal disorders68
-
08-Drugs for female reproductive system61
-
Endocrine Module75
-
09-Drugs for pregnancy56
-
Dosage Calc Module16
-
10-Diabetes Lec39
-
11-Drugs affecting the ANS45
-
12-Drugs for local and general anesthesia56
-
13-Drugs for Pain46
-
14-Drugs for inflammation45
-
15-Drugs for Mood Disorders52
-
16-Drugs for Psychoses and Degenerative Diseases of the CNS55
-
17-Drugs for Hypertension80
-
18-Drugs for Lipid Disorders50
-
19-Drugs for Angina, MI and CVA78
-
20-Drugs for Coagulation Disorders71
-
21-Drugs for Pulmonary Disorders44
-
22-Drugs for Nausea and Vomitting38
-
Module- Cardiovascular System52
-
Module- CNS79
-
Module- Drugs for Peptic Ulcers85
