Cardiac Failure, Heart sounds, and Circulatory shock

Question 1

What is cardiac Failure

Answer 1

Failure of the heart to pump enough blood to satisfy the needs of the body

Question 2

What are the ways the sympathetic innervation compensates for acute cardiac failure

Answer 2

strengthens muscle contraction (both undamaged and damaged)

Increases tone of most vessels, especially the veins (note that this increases mean systemic filling pressure)

Question 3

What are the 3 compensatory mechanisms by the ANS for acute cardiac failure

Answer 3

Baroreceptor reflex
Chemoreceptor relfex
CNS ischemic response

Question 4

Sympathetic innervation raises the mean systemic filling pressure from from 7 mmHg to

Answer 4

12-14 mmHg thus increasing the tendency for blood to flow from the veins back to the heart

Question 5

What are the acute dynamic changes after an MI

Answer 5

Reduced Cardiac output

Damming of blood in the veins—> increased venous pressure

Question 6

Acute dynamic changes due to MI are compensated by

Answer 6

sympathetic innervation

Question 7

Chronic dynamic changes due to MI are compensated by (compensated heart failure)

Answer 7

Compensated heart failure is the result of partial heart recovery and renal retention of fluid
Maximum pumping ability of the partly recovered heart is still depressed to less than one-half normal
Increase in right atrial pressure can maintain the cardiac ouput at a near normal level despite continued weakness of the heart

Question 8

Why do patients with heart failure get pulmonary edema and not acute peripheral edema

Answer 8

As cardiac ouput decreases the right atrial pressure increases, the aortic pressure greatly decreases, and the capillary pressure reduces (this leads to reduced chance of peripheral edema)

Question 9

Why does left heart failure lead to pulmonary edema

Answer 9

blood is pumped into lungs, but it is not pumped adequately out of the lungs
Therefore, the mean pulmonary filling pressure rises because of the shift of large volumes of blood form the systemic circulation to the pulmonary circulation
This leads to pulmonary capillary pressure increase
once pulmonary capillary pressure rises above or equal to the colloid osmotic pressure of the plasma (about 28mmHg) then fluid begins to filter out of the capillaries into the lung interstitial spaces and alveoli, resulting in pulmonary edema

Question 10

What are the two major problems of left heart failure

Answer 10

pulmonary vascular congestion

pulmonary edema

Question 11

What are two forms of high output cardiac failure

Answer 11

Arteriovenous fistula

Beriberi

Question 12

Beriberi is what kind of deficiency

Answer 12

Thiamin

Question 13

What is the first heart sound

Answer 13

AV valves close at the onset of ventricular systole

Question 14

What is the second heart sound

Answer 14

Semilunar valves close at the end of systole

Question 15

List 7 valvular heart defects

Answer 15

valvular lesions, rheumatic valvular lesions, heart murmurs, aortic stenosis, aortic regurgitation, Mitral regurgitation, Mitral stenosis

Question 16

In a healthy person the arterial pressure can usually be reduced below about 45 mmHg before cardiac deterioration sets in. However, in a heart that already has a blocked major coronary vessel, deterioration begins when the coronary aterial pressure falls below

Answer 16

80 to 90 mmHg

Question 17

What is a rapid acting diuretic used in patients with flash pulmonary edema

Answer 17

furosemide

Question 18

The maximum percentage that the cardiac ouput can increase above normal is called

Answer 18

cardiac reserve

Question 19

Decompensation of the heart is caused by

Answer 19

the heart never being able to reach the cardiac ouput of 5 L/min, even as venous return increases due to fluid retention.

Question 20

Mitral regurgiation occurs during

Answer 20

systole

Question 21

Aortic regurgitation occurs during

Answer 21

Diastole

Question 22

When is it possible to hear mitral valves stenosis heart sounds

Answer 22

it is extremely quite due to the low pressure in the left atria. Best chance is in the last 2/3 of diastole

Question 23

What is Patent ductus arteriosus

Answer 23

(left-to-right shunt)-

Blood flows from aorta to pulmonary trunk

Question 24

Tetralogy of Fallot

Answer 24

(right-to-left shunt)

Blood flows from right atria to left atria

Question 25

Cardiac abnormalities that decrease the ability of the heart to pump blood

Answer 25

Myocardial infarction
Toxic state of the heart
severe heart valve dysfunction
heart arrhythmias
Circulatory shock that results from diminished cardiac pumping ability is called cardiogenic shock

Question 26

Factors that decrease venous return

Answer 26

diminished blood volume
Decreased vascular tone (especially of venous reservoirs)
Obstruction of blood flow

Question 27

Powerful sympathetic reflexes initiated by arterial baroreceptors and other vascular stretch receptors in attempt to return cardiac output to normal following cardiac shock

Answer 27

Arterioles constrict in most parts of the systemic circulation
The veins and venous reservoirs constrict
Heart activity increases markedly (up to 160-180 bpm)

Question 28

Autoregulation in cerebral and cardiac vessels maintains more-or-less normal pressure as long as the arterial pressue does not fall below

Answer 28

70 mmHg

Question 29

Factors that cause a person to recover from a moderate degree of cardiac shock

Answer 29

• Baroreceptor reflex
• Central nervous system ischemic response (activated at pressures below 50mmHg)
• Reverse stress-relaxation of the circulatory system
• Increased secretion of renin by the kidneys and formation of angiotensin II
• increased secretion by the posterior pituitary gland of vasopressin (ADH)
• Increased secretion by the adrenal medullae of epinephrine and norepinephrine

Question 30

Compensatory mechanisms that return blood volume back to normal

Answer 30

absorption of large quantities of fluid form the intestinal tract
absorption of fluids into the blood capillaries from the interstitial spaces of the body
conservation of water and salt by the kidneys
Increased thirst and increased appetite for salt

Question 31

What is progressive shock

Answer 31

when shock itself causes still more shock
- results from positive feeback
When arterial pressure falls low enough, coronary blood flow decreases below that required for adequate nutrition of the myocardium. This weakens the heart muscle and decreases cardiac output even more
- one of the most important features of progressive shock whether or not it is hemorrhagic in origin

Question 32

What is non-progressive shock

Answer 32

Sympathetic reflexes and other factors compensate enough to prevent further deterioration of the circulation (all of these are negative feedback mechanisms that attempt to return cardiac output and arterial pressure back to normal)

Question 33

Factors in the final lethal progression of shock

Answer 33

Vasomotor failure
blockage of small vessels (sludge blood) 
increased vascular permeability
release of toxins by necrotic tissue
cardiac depression caused by endotoxin
generalized cellular deterioration

Question 34

What is meant by generalized cellular deterioration

Answer 34

Diminished active transport of sodium and potassium though cell membrane
depressed mitochondrial activity
breakdown of lysosomes
depression of cellular metabolism of nutrients

Question 35

What is neurogenic shock

Answer 35

shock may occur without any loss of blood volume
the vascular capacity increases so much that even the normal amount of blood becomes incapable of filling the circulatory system adequately
one of the major causes of the above is sudden loss of vasomotor tone, resulting in massive dilation of the veins

Question 36

What are some causes of neurogenic shock

Answer 36

Deep general anesthesia- depresses vasomotor center enough to cause vasomotor paralysis
Spinal anesthesia- blocks sympathetic nervous outflow
brain damage- causes vasomotor paralysis