chapter 22 cardiac failure

Question 1

define cardiac failure

Answer 1

failure of the heart to pump enough blood to satisfy the body’s needs

Question 2

2 acute effects from cardiac failure

Answer 2

reduced cardiac output, damming of blood in the veins which increases venous pressure

Question 3

name some ways the body compensates for acute cardiac failure by sympathetic responses

Answer 3

baroreceptor reflex, chemoreceptor reflex, CNS ischemic response.

Question 4

4 detrimental effects of excess fluid retention in severe cardiac failure

Answer 4

1. increasing the work load of heart, 2. overstretcthing the heart which weakens the heart, 3. filtration of fluid into the lungs, causing pulmonary edema and deoxygenation of blood, 4. development of edema in the body

Question 5

decompensated heart failure is what

Answer 5

the damage is so much that the body cannot compensate at all. The kidneys cant excrete enough fluid and edema develops all throughout the body

Question 6

What is the critical cardiac output level required in a normal adult?

Answer 6

5L of blood a minute

Question 7

Failure of the cardiac output to rise to the critical level required for normal renal function results in 3 things

Answer 7

1. retention of more and more fluid, 2. Progressive elevation of mean systolic filling pressure, 3. progressive elevation of right atrial pressure

Question 8

how can the decompensation process be stopped?

Answer 8

1. strengthening the heart with cardiotonic drugs like digitalis. This makes the heart strong enough to pump enough blood for proper kidney function.
2. administering diuretic drugs to increase kidney excretion

Question 9

how do cardiotonic drugs like digitalis and cardiotonic glycosides strengthen the heart?

Answer 9

increase the amount of calcium ions in the muscle fibers

Question 10

describe pulmonary edema

Answer 10

when the left heart fails without the right. Blood is pumped into the lungs quicker than the blood can be pumped out of the left heart. This causes the mean pulmonary filling pressure to rise which increases the pulmonary capillary pressure. If it rises above the colloid pressure it filters out of the capillaries into the interstitial spaces of the alveoli causing edema

Question 11

define cardiac shock

Answer 11

inadequate cardiac pumping

Question 12

Can acute left heart failure cause death?

Answer 12

yes, within minutes to hours

Question 13

Why does acute cardiac failure not cause peripheral edema?

Answer 13

Becaue the capillary pressure actually falls not increases. ( since the left heart isnt pumping well, the aortic pressure falls, which means the peripheral capillary pressure falls, but the right atrial pressure increases.)

Question 14

what actually causes the peripheral edema?

Answer 14

long term retention by the kidneys

Question 15

whats happening with pressures during long term kidney retention? (specifically the right atrial and the capillary pressures)

Answer 15

This increases the blood to the heart which increases the right atrial pressure and returns the aterial pressure back to normal. Now there is an increase in Capillary pressure which causes the peripheral edema.

Question 16

name some common reasons of reduced renal output of urine during cardiac failure

Answer 16

decreased glomerular filtration rate, activation of renin-angiotensin system and increased reabsorption of water and salt by renal tubules, increased aldosterone secretion, activation of sympathetic nervous system

Question 17

What is ANP and where is it found and what does it do?

Answer 17

Atrial natriuretic peptide, released by atrial walls when they are stretched and it tells the kidneys to increase excretion of salt and water

Question 18

describe the vicious acute pulmonary edema circle

Answer 18

a weak left heart leads to pooling of blood in lungs, this leads to less oxygenated blood which further weakens the heart, this leads to peripheral vasodilation which pushes more blood to the lungs which pools more blood into the lungs. ( this repeats and repeats)

Question 19

therapeutic measures for those going through the pulmonary edema circle

Answer 19

tourniquets on limbs, duretic to loose fluid, oxygen mask, cardiotonic drug like digitalis to strengthen heart

Question 20

what is cardiac reserve

Answer 20

the maximum percentage that the cardiac output can increase above normal .

Question 21

whats the cardiac reserve in a adult

Answer 21

300-400%

Question 22

Diagnosis of low cardiac reserve

Answer 22

1. shortness in breath( dyspnea),2. muscle fatigue, 3. increase in heart rate.

Question 23

name 2 conditions that cause high cardiac output failure

Answer 23

Arteriovenous fistula, beriberi

Question 24

Arteriovenous fistula

Answer 24

This is a direct opening between a large artery and large vein. This decreases vascular resistance. This causes a raise in venous return which pretty much overloads the heart and lowers the cardiac reserve since it is alreay near its maximum capacity to pump blood through the AV fistula

Question 25

Beriberi

Answer 25

Decreased cardiac output is caused by weakening of the heart from avitaminosis( lack of vitamins, specifically thiamine (B1)). Weak heart means less blood to the kidneys which causes retaining of fluid. This also causes a rise in venous return.