Physiology: Chapter 22 Cardiac Failure

Front 1

At 0mmHg right atrial pressure what is the CO?

Back 1

5L/min

Front 2

When compensation occurs in HF what happens to the the right atrial pressure?

Back 2

it increases

Front 3

What are the 3 sympathetic reflexes that are activated in HF?

Back 3

baroreceptor, chemoreceptor, and CNS ischemic response reflex

Front 4

What are the 2 ways that increased blood volume increases venous return to the heart?

Back 4

1) it increases mean systemic filling pressure
2) it distends the veins which reduces the venous resistance

Front 5

Why do the kidney's continue to retain water and salt, which acutely during heart failure is good, but long term is detrimental?

Back 5

CO continues to decrease in HF which decreases renal perfusion with oxygen so the kidneys continue to retain fluid and electrolytes which leads to edema and eventually death

Front 6

Excess fluid retention has what adverse complications?

Back 6

1) over stretching the heart
2) pulmonary edema
3) reduced oxygen exchange in lungs
4) edema through out body

Front 7

What two events pertianing to cell growth occur after an MI?

Back 7

1) angiogenesis to nondamaged areas
2) hypertrophy of remaining functional mycardium

Front 8

5 weeks post MI the cardiac output can return to 5L/min. What is different between someone post MI and a normal person when they both have a CO of 5L/min.

Back 8

The heart in the post MI person is working at max, whereas the normal heart has a large reserve left before it reaches max CO

Front 9

A person 5 weeks post MI seems to be recovering well. Are his kidney's retaining or losing fluid?

Back 9

Once CO is 5L/min the renal output of urine returns to normal

Note: the fluid that has already been retained remains so that there is moderate fluid excess

Front 10

In compensated HF what are the sequence of events that occur to increase CO?

Back 10

1) initial damage lowers CO
2) symphatetics raise
3) fluid retention
4) structural changes at heart

Front 11

If the left ventricular pressure is low, what happens to the right atrial pressure?

Back 11

it increases, this happens to compensate for heart failure

Front 12

What is reduced in compensated HF?

Back 12

cardiac reserve

Front 13

In decompensated HF the increase in fluid volume is not able to increase CO. At this stage what is occurring physiologically in the ventricles?

Back 13

they are overstretched and dilated from the increased fluid

Front 14

On physical exam how could you tell if someone had decompensated HF?

Back 14

they have peripheral and pulmonary edema which results in rales heard on auscultation. they will also have dyspnea

Front 15

How is the decompensated heart treated?

Back 15

1) digitalis to strengthen contractions
2) diuretics to reduce blood volume and edema

Front 16

If digitalis is given to someone with a normal heart what results?

Back 16

little change or effect on strength of contraction. only works in HF

Front 17

In left sided HF what happens to the mean pulmonary filling pressure?

Back 17

it increases becuase the right ventricle is pumping harder and blood is pooling in lungs

Front 18

When CO gets very low it is known as?

Back 18

cardiac shock

Front 19

If cardiogenic shock occurs in someone with an infarct, what can be given to try and increase coronary vessel perfusion of blood?

Back 19

1) digoxin and infusion of whole blood and plasma
2) streptokinase adn tPA

Front 20

What is the atrial pressure in someone who has a high aortic pressure?

Back 20

low atrial

Front 21

What pressure in acute HF is reduced and prevents edema?

Back 21

capillary pressure

Front 22

Why in someone with acute HF do you not see peripheral edema?

Back 22

because the capillary pressure falls with decreased CO. Peripheral edema only occurs later (after 1st day) when the kidneys have retained excess water during decompensated HF

Front 23

In HF what happens to glomerular filtration rate?

Back 23

decreases

Front 24

How does capillary pressure remain relatively constant in HF? How does edema result if capillary pressure is relatively constant?

Back 24

1) as the aortic pressure decreases the right atrial pressure increases keeping the capillary pressure relatively constant in HF
2) the peripheral tissues become relatively hypertonic to the blood and therefore water moves out of the hypotonic blood, which is dilute from renal retention of water, into the extravascular space causing edema

Front 25

What is angiotensins effect on the kidney?

Back 25

decrease afferent arteriolar blood flow thus decreasing GFR and increased reabsorption of fluid and salt

Front 26

What happens to capillary pressure surrounding the renal tubules when angiotensin is released?

Back 26

the capillary pressure decreases so that more reabsorption can occur

Front 27

What hormone does angiotensin stimulate the release of to further promote fluid retention?

Back 27

aldosterone

Front 28

What electrolyte in the blood is a powerful stimulant for aldosterone release?

Back 28

potassium which rises in HF

Front 29

What hormone is released from the atria when they stretch?

Back 29

ANP

Front 30

What is the relation of ANP to aldosterone?

Back 30

opposite, ANP increases excretion of water and electrolytes

Front 31

Describe the cycle of events in someone with chronic HF that suddenly develops fatal pulmonary edema!

Back 31

1) begins with stressor, such as anxiety
2) this temporarily increases work of weak ventricle and blood begins to back up
3) pulmonary capillary pressure develops
4) develop pulmonary edema
5) decreased oxygen exchange
6) decreased oxygen further weakens heart
7) deprived of nutrients and O2 peripheral vasodilation occurs
8) This increases venous return to heart
9) which causes further damming of blood in lungs

Front 32

What are ways to treat acute pulmonary edema?

Back 32

1) tourniquets of extremities to sequester blood flow
2) bleeding patient
3) diuretic
4) pure oxygen
5) digoxin

Front 33

What percentage above normal is the cardiac reserve?

Back 33

400% but up to 600% in athlete

Front 34

What is the trend of venous return, CO and right atrial pressure in someone with HF?

Back 34

CO decreases and venous return increases a lot to try to increase CO. The right atrial pressure increases as a result of increased venous return

Front 35

Why does decompensation result?

Back 35

because the CO never reaches 5L/min to establish normal kidney excretion of fluid

Front 36

Digitalis is known to cause an increase in CO above 5L/min. what effect is normally then observed?

Back 36

diuresis is a common effect of digitalis becuase CO increases allowing the kidneys to excrete excess fluid

Front 37

What is the effect on CO, right atrial pressure and venous return if someone has an AV shunt? Why?

Back 37

They all increase because systemic resistance decreases

Front 38

What is the effect on CO, right atrial pressure and venous return if someone has beriberi?

Back 38

They all increase

Front 39

In beriberi and AV shunt what happens to cardiac reserve?

Back 39

it decreases

Front 40

What is the cause of beriberi?

Back 40

lack of thiamine (vit B1)

Front 41

Why does the heart become continually weakened in beriberi?

Back 41

the heart muscle is already weak and decreased renal blood flow increases blood volume leading to a further decrease in heart function

Front 42

Which condition, AV shunt or beriberi, has a larger venous return? Why?

Back 42

beriberi because the kidney does not adequately perfused so it contains to increase blood volume which increases venous return