Lecture 14: HF, Sounds, Shock

Question 1

Define Cardiac failure

Answer 1

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

Question 2

Compensation for acute HF

Answer 2

Number of circulatory reflexes are activated in order to increase activation of the symapthetic innervation to the heart and decrease parasympathicteic innervation

• strengthens muscle contraction
• increases tone of most vessels, esp. veins- increases Psf

Question 3

3 responses from ANS d/t acute HF :

Answer 3

Baroreceptor reflex

Chemoreceptor reflex

CNS ischemic response

Question 4

Strong sympathietic stimulation d/t all ventricular function diffuesly damages but still functional:

Answer 4

Also if part of musculature is damaged—

Increases tone of most blood vessel of circulation and therefore increases venous return

Raises Psf!!! To 12-14 mm Hg

This increases tendency for flow from the veins back into the heart

Question 5

Acute effects following AMI:

Answer 5

Reduced CO

Damming of blood in the veins- increased venous pressures

Causes compensation by sympathetic NS

Question 6

Chronic compensation for MI- heart failure

Answer 6

Result from partial heart recovery and renal fluid retention.

Max. Pumping ability o the partylt recovered heart is stil depressed to less than 1/2 norm.

Heavy exercise generally causes return of symptoms back to acute HF stage….

Increase in r atrial pressure can maintain the CO at a near norm level despite continues weakness of the heart

Question 7

Pressure changes in HF:

Answer 7

Increase in R atrial pressure

Decrease in mean Aortic pressure

Question 8

Fall in capillary pressure reduces :

Answer 8

Chances of peripheral edema

Question 9

Pulmonary edema and L HF:

Answer 9

L side of heart fails w/o concomitant failure of R side

Blood continues to be pumped to lungs but not adequately out of the lungs

Pulmonary filling pressure rises b/c of shift of large volumes from systemic into pulmonary circulation

Pulmonary capillary pressure increases

If rising to pressure = colloid osmotic pressure of plasma -28mm Hg fluids begins to filter out of capillary into lung lung interstitial spaces and alveoli resulting in pulmonary edema

Question 10

2 major problems w/ L HF:

Answer 10

Pulmonary vasucular congestion

Pulmonary edema

Question 11

Pulmonary edema onset:

Answer 11

Can occur so rapidly that if can cause death by suffocation in 20-30min.

Question 12

What drug may function on a chronically failing heart by increasing the [ca++] in muscle fibers, thereby increasing the strength of contraction

Answer 12

Digitalis

Question 13

What conditions can lead to high output heart failure?

Answer 13

Arteriovenous fistula: overloads heart-excessive venous return. Curve moves upwards.

Beriberi: heart muscle weakens d/t thiamine deficiency. Shift venous curve to the right. Results in decreased blood flow to kidneys.

Question 14

What is first sound of heart?

Answer 14

AV valves closing- onset of ventricular systole

Question 15

What is second sound of heart?

Answer 15

Semilunar valves closing- end of systole.

Question 16

Distinguish btw left to right and right to left congenital defects

Answer 16

L to R: Patent ductus arteriosus- blood flows backwards and fails to flow through systemic circulation.

R to L: Tetralogy of fallot- blood flows from R to L side of heart- bypassing lungs.

Question 17

How is a patent ductus arteriosus L to R:

Answer 17

Blood flows backwards [L to R] from aortic arch to pulmonary arch

[essentially, L ventricle to R]

Question 18

How is tetralogy of FA loot a R to L defect:

Answer 18

W/ a defect in the interventricular wall blood will flow out of the R venticle into the L ventricle

[R to L]

Question 19

Define circulatory shock

Answer 19

Generalized Inadequate blood flow through the body, to the extent that the body tissues are damaged. Especially because of too little O2 and other nutrients delivered to the tissue cells

Question 20

List 2 factors that reduce CO and give ex:

Answer 20

Diminished blood volume~20%.
Decreased vascular tone.
Obstruction of blood flow.

Ex: MI, Heart arrhythmia, toxic heart state, severe heart valve dysfunction, circulatory shock that results from diminished cardiac ability-cardiogenic shock.

Question 21

Negative feedback mechanisms that attempts to return cardiac output and arterial pressure back to normal after cardiac shock?

Answer 21

Sympathetic reflex: initiated by arterial baroreceptors.

autoregulation for art. pressure as long as it doesnt drop elbow 70 mm Hg

Question 22

What results from sympathetic stimulation reflex after arterial baroreceptor has initiated the reflex?

Answer 22

Results in: arterioles and venous constriction and increase in HR up to 180 bpm

Question 23

Factors that cause a person to recover from shock:

Answer 23

• baroreceptor reflexes
• central nervous system ischemic response
• reverse stress-relaxation of the circulatory system
• Renin-angiotensin response

Question 24

What effects does renin cause?

Answer 24

Constricts peripheral arteries and causes DECREASED outputs of water and salt by the kidneys.

Question 25

What effect does ADH have?

Answer 25

Constricts peripheral arteries and veins and greatly increases water retention by the kidneys.

Question 26

What effect does epinephrine have in shock?

Answer 26

Constricts the peripheral arteries and veins and increases HR

Question 27

What are 4 compensatory mechanisms for returning blood volume back to normal?

Answer 27

• Absorption of large quantities of fluid from GI tract
• absorption of fluids into blood capillaries from GI tract
• increased thirst and increased appetite for salt

-conservation of water and salt by the kidneys

Question 28

Progressive vs non-progressive shock

Answer 28

Non-progressive shock : sympathetic relaxes CAN compensate enough for shock. NEGATIVE feedback mechanisms

Progressive shock: POSITIVE feedbacks. Art. Pressure is low enough coronary blood flow is too low-decreasing heart muscle and CO even more. Important feature;hemorrhagic or not

Question 29

Lethal factors in progression of shock

Answer 29

• Vasomotor tone
• blockage of small vessels
• increased vascular permeability
• release of toxins by necrotic tissue.
• cardiac depression d/t endotoxins
• generalized cellular deterioration:decreased active transport, mito. Activity, lysosome breakdown, depression of cellular metabolism.

Question 30

Define neurogenic shock

Answer 30

Shock that occurs w/o blood loss.

Vascular capacity increases so much that even the normal amount of blood becomes incapable of filling the circulatory adequately

Question 31

Causes of neurogenic shock:

Answer 31

Major: loss of vasomotor tone, resulting in massive dilation of veins.

Others: general anesthesia, spinal anesthesia, brain damage

Question 32

Objective 4: Describe progressive changes that occur in cardiac output, Psf, and R atrial pressure after AMI:

Answer 32

Initially CO/ venous return drops d/t AMI. Then, Sympathetic innervation and partial recover will gradually increase CO again. It likely will never be as high as before.

This is with a compensated heart.

Question 33

What happens after AMI for a decompensated heart?

Answer 33

The heart is never able to come all the way back to the level req’d for critical CO level for fluid balance.

After decreasing initially it begins to improve…then it decreases again because it is unable to compensate.