Lecture 26

Question 1

What constitutes heart failure?

Answer 1

1. Failure of heart to pump adequate blood to satisfy body’s needs
2. Certain conditions or diseases lead to a decrease in CO
3. Can involve the right ventricle, left ventricle or both

Question 2

Disorder of coronary arteries, hypertension, cardiomyopathy, heart valve disorder, abnormal heart rhythm can lead to a decrease in _____ _____.

Answer 2

CO

Question 3

T or F? With time, failure of one ventricle leads to failure of the other.

Answer 3

True

Question 4

What are characteristics of systolic heart failure?

Answer 4

1. Dysfunctional mechanical pumping
2. Most often caused by coronary artery disease which reduces coronary blood flow to heart leading to hypoxia and impaired contractility.
3. Reduced cardiac output and ejection fraction

Question 5

Dysfunctional mechanical pumping in systolic heart failure leads to decreased _________.

Answer 5

Contractility

Question 6

Systolic heart failure, often caused by coronary artery disease, reduces coronary blood flow to heart leading to hypoxia and impaired contractility. What events leads to ↓CO and ↓EF?

Answer 6

Impaired contractility→ ↓SV → ↑ESV → ↑EDV/preload → with a chronic increase in EDV, the ventricle remodels by dilating (enlargement) → ↓force development→ ↓SV → reduced cardiac output and ejection fraction.

Question 7

What is a good indication of systolic heart failure?

Answer 7

Reduced cardiac output and ejection fraction are good indication.

Question 8

What are characteristics of diastolic heart failure?

Answer 8

1. Inadequate relaxation and reduced filling
2. Most often caused by hypertension → ↑ afterload → stimulation of ventricular hypertrophy → ↑ stiffness (↓ compliance) → ↓filling → ↓EDV → ↓SV → ↓CO
3. Reduced cardiac output, but ejection fraction may be near normal; thus reduced EF is useful only as an indicator of systolic failure

Question 9

T or F? Pressure overload leads to dilation of chambers (enlargement; cardiomegaly); volume overload (i.e. increased afterload) leads to hypertrophy of chambers (thicker walls).

Answer 9

False, the opposite is true.
Volume → enlargement
Pressure → hypertrophy of chambers

Question 10

How does the body compensate for heart failure?

Answer 10

By the activation of SNS and RAAS. (however, it causes progressive weakening of heart)

Question 11

Long-term activation of the SNS and RAAS contributes to weakening of the heart is because they ultimately increase the ______ of the heart, which puts a strain on the heart muscle.

Answer 11

work (The SNS and RAAS increase the oxygen demand of the heart muscle, it has to work harder to deliver that oxygen or the muscle will become hypoxic. Hypoxia will cause weakening. It is a vicious cycle.)

Question 12

What are the effects of the SNS?

Answer 12

1. Tachycardia (increases O2 consumption)
2. Increases contractility (increases O2 consumption)
3. Venoconstriction (increases preload, which increases O2 consumption)
4. Vasoconstriction (increases afterload, which increases O2 consumption) )
5. Chronic norepinephrine exposure is toxic to myocardial cells (causes apoptosis)
6. Increases risk of arrhythmias which can decrease CO

Question 13

What are the effects of RAAS: Ang II?

Answer 13

1. Vasocontriction (increases afterload)
2. Stimulates renal sodium and water reabsorption (increases blood volume and preload)
3. Stimulates SNS
4. Stimulates ventricular remodeling (which causes dysfunction)

Question 14

What are the effects of RAAS: Aldosterone?

Answer 14

1. Stimulates renal sodium and water reabsorption (increases blood volume and preload)
2. Stimulates interstitial cardiac fibrosis (causing stiffness and dysfunction)
3. Increases risk for arrhythmias

Question 15

What other hormones contributes to heart failure?

Answer 15

Norepinephrine, Angiotensin II, Aldosterone, ADH

Question 16

What is the decompensation stage of heart failure?

Answer 16

The heart has been compensating for years trying to maintain proper CO levels but slowly gets weaker over time. CO eventually decreases to an inadequate level. The RAAS and SNS can no longer compensate.

Question 17

What are signs and syptoms of heart failure?

Answer 17

1. Tachycardia
2. Decreased cardiac reserve and decreased exercise tolerance
3. Shortness of breath
4. Peripheral and/or pulmonary edema
5. Cardiomegaly (dilation of heart; enlargement)—Note: even if hypertrophy initially is present, chronic volume overload will lead to dilation.

Question 18

What is cardiac reserve?

Answer 18

The work that the heart is able to perform beyond that required under the ordinary circumstances.

Question 19

What are some treatment strategies for heart failure?

Answer 19

Depends on stage of disease, treatment in the compensated stage:
Inhibit actions of SNS - β-blockers
Inhibit actions of RAAS -ACE inhibitors. ARBs, Aldosterone antagonists
Other Diuretics, Decrease salt and water intake

Question 20

Pulmonary Edema is _____ heart failure. (pulmonary cap wedge pressure is higher)

Answer 20

Left

Question 21

Systemic Edema is _____ heart failure.

Answer 21

Right