Lecture 13 Cardiac Failure, Heart Sounds, and Circulatory Shock

Question 1

Define Cardiac Failure

Answer 1

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

Question 2

Compensation for acute cardiac failure, effects of sympathetic innervation:

Answer 2

Strengthens muscle contraction (both undamaged and damaged)

Increases tone of most vessels, especially veins–> increases mean systemic filling pressure

Question 3

Compensatory mechanisms by ANS for acute cardiac failure:

Answer 3

Baroreceptor reflex
Chemoreceptor reflex
CNS ischemic response

Question 4

Strong Sympathetic Stimulation - If all the ventricular musculature is diffusely damaged but is still functional then:

Answer 4

Sympathetic system strengthens this damaged musculature

Question 5

Strong Sympathetic Stimulation - If part of the musculature is nonfunctional and part is still normal then:

Answer 5

The normal muscle is strongly stimulated

Question 6

Strong Sympathetic Stimulation - Increases tone of most of the blood vessels of the circulation and, therefore, increases venous return:

Answer 6

Raises mean systemic filling pressure to 12 to 14 mm Hg, increasing the tendency for blood to flow from the veins back into the heart

Question 7

Circulatory Change Dynamics (Following Acute Heart Attach) - Acute effects:

Answer 7

Reduced cardiac output

Damming of blood in the veins –> increased venous pressure

Question 8

Pulmonary Edema and Left Heart Failure (wordy)

Answer 8

Left side of heart fails w/o failure of right side
Blood continues to be pumped into lungs, bt it is not pumped adequately out of lungs.
Mean pulmonary filing pressure rises b/c of the shift of large vol. of blood from systemic circ. into the pulmonary circ.
Pulm. capillary pressure increases
If rises above value approx. equal to the colloid osmotic press. of the plasma, fluid begins to filter out of the caps. into the lung interstitial spaces & alveoli, = pulmonary edema.

Question 9

Two major problems of left heart failure:

Answer 9

Pulmonary vascular congestion

Pulmonary edema

Question 10

Conditions that result in High Output Cardiac Failure

Answer 10

Arteriovenous Fistula

Beriberi

Question 11

Arteriovenous Fistula

Answer 11

Overloads heart because of excessive venous return

Venous return curve rotates upward (Fig. 22-8)

Question 12

Beriberi

Answer 12

Thiamin deficiency
Weakening of heart
Decreased blood flow to kidney –> fluid retention
Increased mean filling pressure
Shift of venous return curve to right (Fig. 22-8)

Question 13

First Heart Sound

Answer 13

AV valves close at the onset of ventricular systole

Question 14

Second Heart Sound

Answer 14

Semilunar valves close at the end of systole

Question 15

Valvular Defects

Answer 15

Valvular lesions
Rheumatic valvular lesions
Heart murmurs
Aortic stenosis
Aortic regurgitation
Mitral regurgitation
Mitral stenosis

Question 16

Describe Left-to-right shunt and give example

Answer 16

Blood flows backward and fails to flow through systemic circulation
Ex. Paten ductus arteriosus

Question 17

Describe Right-to-left shunt and give example

Answer 17

Blood flows from right to left side of heart, bypassing lungs
Ex. Tetralogy of Fallot

Question 18

Define Circulatory Shock

Answer 18

Generalized inadequate blood flow through the body, to the extent that the body tissues are damaged, especially because of too little oxygen and other nutrients delivered to the tissue cells

Question 19

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

Answer 19

Myocardial infarction
Toxic state of the heart
Severe heart valve dysfunction
Heart arrhythmias

Question 20

Factors reducing cardiac output

Answer 20

Cardiac abnormalities that decrease the ability of the heart to pump blood.
Factors that decrease venous return.

Question 21

Circulatory shock that results from diminished cardiac pumping ability is called _______ ____.

Answer 21

Cardiogenic shock

Question 22

Factors that decrease venous return:

Answer 22

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

Question 23

Powerful sympathetic reflexes are initiated mainly by:

Answer 23

Arterial baroreceptors and other vascular stretch receptors

Question 24

Powerful sympathetic reflexes result from:

Answer 24

Decrease in arterial pressure after hemorrhage

Decreases in pressures in the pulmonary arteries and veins in the thorax

Question 25

Negative feedback mechanism reflexes result in three important effects:

Answer 25

Arterioles constrict in most parts of the systemic circulation The veins and venous reservoirs constrict Heart activity increases markedly

Question 26

Autoregulation in _____ and _____ vessels maintain more-or-less normal pressure as long as the arterial pressure does not fall below ____ mm Hg.

Answer 26

Cerebral and cardiac vessels | 70 mm Hg

Question 27

Factors that cause a person to recover from moderate degrees of shock:

Answer 27

See slides 61 and 62

Question 28

Compensatory mechanisms that return blood volume back to normal:

Answer 28

Absorption of large quantities of fluid from the intestinal tract Absorption of fluid into blood capillaries from the interstitial spaces of the body Conservation of water and salt by the kidneys Increased thirst and increases appetite for salt

Question 29

Non-progressive Shock

Answer 29

Sympathetic reflexes & other factors compensate enough to prevent further deterioration of the circulation. All these factors are neg. feedback mechanisms that attempt to return cardiac output & arterial pressure back to normal

Question 30

Progressive shock

Answer 30

Positive feedbacks When arterial pressure falls low enough, coronary blood flow decreases below that required for adequate nutrition of the myocardium. This weakens the heart muscle & decreases cardiac output even more

Question 31

What is one of the most important features of progressive shock?

Answer 31

Whether or not it is hemorrhagic in origin

Question 32

Factors in the Final Lethal Progression of Shock:

Answer 32

``` Vasomotor failure Blockage of small vessels (sludged blood) Increased vascular permeability Release of toxins by necrotic tissue Cardiac depression caused by endotoxin Generalized cellular deterioration ```

Question 33

Generalized Cellular deterioration:

Answer 33

Diminished active transport of sodium and potassium through cell membrane Depressed mitochondrial activity Breakdown of lysosomes Depression of cellular metabolism of nutrients

Question 34

True or False: | Neurogenic shock may occur without any loss of blood volume

Answer 34

True

Question 35

Neurogenic shock

Answer 35

The vascular capacity increases so much that even the normal amount of blood becomes incapable of filling the circulatory system adequately --> major cause is sudden loss of vasomotor tone, resulting in massive dilation of the veins

Question 36

Causes of neurogenic shock

Answer 36

Deep general anesthesia Spinal anesthesia Brain damage

Question 37

Describe how deep general anesthesia causes neurogenic shock

Answer 37

Depresses vasomotor center enough to cause vasomotor paralysis

Question 38

Describe how spinal anesthesia causes neurogenic shock

Answer 38

Blocks sympathetic nervous outflow

Question 39

Describe how brain damage causes neurogenic shock

Answer 39

Causes vasomotor paralysis