Cardiac Failure

Question 1

What is cardiac failure?

Answer 1

Cardiac failure: failure of the heart to pump enough blood to satisfy the needs of the body.

Question 2

What are activated during cardiac failure?

Answer 2

Many circulatory reflexes are activated in order to increase activation of sympathetic innervation to the heart and decrease parasympathetic innervation.

Question 3

During cardiac failure, what does the sympathetic nervous system do?

Answer 3

Sympathetic – strengthens muscle contractions (damaged and undamaged) and increases the tone of muscles, especially VEINS.

Question 4

How does mean systemic filling pressure change during cardiac failure?

Answer 4

MEAN SYSTEMIC FILLING PRESSURE is increased.

Question 5

When the heart is damaged, what does it try to increase?

Answer 5

When the heart is damaged, it will increase pressure in order to return to normal cardiac output. If it is too damged, pressure will increase, but the flow will never reach 5 L/min

Question 6

What is acute effect?

Answer 6

Acute effect: reduced cardiac output, damming of blood in veins -> increased venous pressure. The sympathetic nervous system attempts to compensate this pressure.

Question 7

What is chronic compensation?

Answer 7

Chronic compensation: results from partial heart recovery and retained fluid. The maxmum pumping ability is reduced. When a person has compensated heart failure, any attempt to perform exercise causes acute failure because the heart is not able to increase its pumping capacity. Increased right atrial pressure maintains the output.

Question 8

How does pressure change during cardiac failure?

Answer 8

In cardiac failure, mean aortic pressure decreases, and capilary and right atrial pressures increase as they approach zero cardiac output.

Question 9

What happens to pulmonary pressure during cardiac failure?

Answer 9

As the left side of the heart fails, the right side continues to be pumped into the lungs, but not adequately OUT of the lungs. Pressure in the pumonary system increases due to the large volume present. It is equal to the colloid osmotic pressure. Fluid filters out of the capillaries into the lung intersitialspaces and alveoli, resulting in an edema.

Question 10

Left heart failure can cause what two conditions?

Answer 10

Two major problems of left heart failure: pulmonary edema and pulmonary vascular congestion. An edema is fatal after 30 minutes.

Question 11

What is given to patients with cardiac failure in order to increase cardiac output to normal?

Answer 11

Digitalis is given to some patients to help increase the level to 5 L/min or higher.

Question 12

How does an ateriorvenous fistula affect cardiac output?

Answer 12

Arteriovenous fistula: overloads the heart because of excessive venous return.

Question 13

How does beri beri affect the heart?

Answer 13

Beriberi: results in a thiamin deficiency, which weakens the heart. The kidneys try to raise pressure via fluid retention, and the venous curve shifts to the right.

Question 14

What are rheumatic valvular lesions?

Answer 14

Rheumatic valvular lesions: autoimmune disorder in which the valves are destroyed. It is initiated by a streptococcal infection.

Question 15

What are heart murmus?

Answer 15

Heart murmurs: abnormal heart sounds caused by valvular lesions.

Question 16

What is an aortic stenosis?

Answer 16

Aortic stenosis: blood is ejected from the left ventricle through only a small fibrous opening of the aortic valve. Resistance to ejection occurs, BP rises to 300 mm HG. It causes severe turbulence of the blood.

Question 17

What is aortic regurgitation?

Answer 17

Aortic regurgitation: during diasatole, blood flows backward from the high pressure aorta into the left ventricle. IT results from turbulence.

Question 18

What is mitral regurgitation?

Answer 18

Mitral regurgitation: blood flows backward through the mitral valve into the left atrium during SYSTOLE.

Question 19

What is mitral stenosis?

Answer 19

Mitral stenosis: blood passes with difficulty through the stenosed mitral valve from the left atrium into the left ventricle. There is little blood in the left ventricle initially, and when it is partially filled, it creates a low rumbling murmur.

Question 20

what is a left-to-right shunt?

Answer 20

Left-to-right shunt: blood flows backward and fails to flow through systemic circulation.

Question 21

What is a right-to-left shunt?

Answer 21

Right-to-left shunt: blood flows from right to left side of the heart, bypassing the lungs.

Question 22

What kind of shunt is patent ductus arteriosis?

Answer 22

Patent ductus arteriosus is a left to right shunt, and teratology of fallot is a right-to-left shunt.

Question 23

What is circulatory shock?

Answer 23

Circulatory shock is the 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 24

What are some cardiac output abnormalities?

Answer 24

Myocardial infarction, toxicity, valve dysfunction, arrythmias, circulatory shock.

Question 25

What are some venous return abnormalities?

Answer 25

Diminished blood volume, decreased vascular tone of venous reservoirs, obstruction of blood flow.

Question 26

What receptors are used by the circulatory system as a negative feedback mechanism?

Answer 26

SYMPATHETICS: baroreceptors. Once activated, a decrease in arterial pressure after hemorrhage, decreases in pressures of the pulmonary arteries and veins.

Question 27

Negative feedback mechanisms/reflexes function to do what?

Answer 27

The reflexes cause arteriole/vein/venous reservoir constriction and increased heart activity.

Question 28

How does the heart attempt to recover from shock?

Answer 28

Shock recovery: baroreceptor reflex -> sympathetic stimulation -> ischemic response -> higher sympathetic stimulation when BP

Question 29

`What is moderate shock recovery?

Answer 29

Moderate shock recovery: increases secretion of renin and formation of angiotensin -> vessel constriction, increased retention of fluid and salt.

Question 30

What hormone is released during moderate shock recovery?

Answer 30

*increased ADH -> artery/vein restriction -> increased retention of water and salt.

Question 31

What neurotransmitters are released during moderate shock recovery?

Answer 31

*also increased epinephrine & norepinephrine -> constriction of arteries/vessels -> increased heart rate.

Question 32

How is blood volume returned to normal?

Answer 32

Return of blood volume to normal:

• absorption of large quantities of fluid from the intestinal tract.
• absorption of fluid from the interstitial fluid by the capillaries.
• conservation of water and salt from the kidneys.
• increased thirst and increased appetite for salt.

Question 33

What is non-progressive shock?

Answer 33

Non-progressive shock: sympathetic reflexes and other factors compensate enough to prevent further deterioration of the circulation. The factors are negative feedback mechanisms that attempt to bring cardiac output and arterial pressure back to normal.

Question 34

What is progressive shock?

Answer 34

Progressive shock: uses positive feedback mechanisms. When arterial pressure is low, blood flow decreases below that is required to support the tissues of the myocardium. This weakens the heart muscle and decreases cardiac output even more.

*Hemorrhaging affects the outcome.

Question 35

What is lethal progression of shock?

Answer 35

Lethal progression of shock: vasomotor failure, blockage of small vessels, increased vascular permeability, release of toxins, cardiac depression, cellular deterioration.

*As cells deteriorate, Na/K pumps and mitochondrial activity decreases.

Question 36

What is neurogenic shock?

Answer 36

Neurogenic shock: shock that occurs WITHOUT loss of blood volume. Massive dilation of blood vessels occurs, and there is not enough blood to fill them.

Question 37

What is neurogenic shock caused by?

Answer 37

Caused by: general anesthesia, spinal anesthesia (blocks sympathetic outflow), or brain damage (causes vasomotor paralysis).