Cardiac Failure Flashcards
What is cardiac failure? How does the ANS compensate for cardiac failure?
Cardiac failure is when the heart loses the ability to pump enough blood to satisfy the needs of the whole body.
Sympathetic Nervous activity is increased and parasympathetic activity is diminished.
-muscle contraction of all damaged and undamaged muscle
Is strengthened
-tone of most vessels, especially veins and blood reservoirs,
Are increased. Which increases mean systemic filling
Pressure (increases the tendency of blood to flow back to the
Heart) and in consequence VR.
ANS:
+ Baroreceptors reflex
+ Chemoreceptors reflex
+ CNS ischemic response
How does the cardiac output curve change after acute myocardial infarction?
The normal cardiac output is 5L/min at about -2 mmHg.
Acute damage/myocardial infarction causes a steeps drop to about 2L/min at a compensated +4 mmHg.
Sympathetic stimulation raises it to about 4.2 L/min at +5 mmHg.
a heart on its way to recovery makes it back to 5L/min at +6 mmHg
> the high RAP is from a retention of fluid
What are the acute effects of a heart attack?
What are the chronic compensations following a heart attack?
Acute effects of heart attack:
-Reduced cardiac output
-damming of blood in the veins -> inc venous
Pressure
SNS compensation
Chronic compensation
+from partial heart recovery and renal retention of fluid
+maximum pumping ability of a partially recovered heart is less
Than 1/2 that of normal.
+any attempt to perform heavy exercise cause an immediate return of the symptoms because the heart cant compensate for the activity.
+increase in RAP can maintain the cardiac output at near normal
How does circulatory pressure change after heart failure?
Pressure in norm: mean aortic: 100, capillary: 17, RAP 0
In cardiac failure half normal: mean aoritc: 70, capillary: 15 and RAP: 6
Cardiac failure with 0 cardiac output: 13 mean aortic pressure, 13 capillary 13, RAP 13. Not enough to pump blood back to the heart but the fall of capillary pressurereduces the chances of peripheral edema.
What are the complications of Left heart failure? And why is peripheral heart failure not developed in left heart failure?
Left heart failure without right heart failure. Blood pumps into the lungs but cant get effectively pumped out of the lungs.
Two major problems of left heart failure:
- Pulmonary vascular congestion
- Pulmonary edema
The large shift of blood from the systemic system to the pulmonary system causes the mean systemic pressure to rise.
The pulmonary capillary pressure increases and if the pressure rises above or almost equal to the Coolidge osmotic pressureof the plasma than fluid filters out of the capillaries nd into the lung interstitial spaces and alveoli.
-> Pulmonary edema: death by suffocation can happen in 20-30 minutes.
The accumulation of blood inthe pulmonary system means there isnt enough blood in the peripherial to led to peripheral edema.
What are the conditions associated with high output cardiac failure?
Ateriovenous fistula
-> heart overloaded because of excessive venous return, VR curve rotates upwards. (Results ina decrease in peripheral vascular resistance)
Beriberi
- > thiamin deficiency
- > weakening of the heart
- > decreased blood flow to kidney->fluid retention
- > increased mean filling pressure
- > VR curve shifted right.
What do the first and second heart sounds refer too?
First sound:
AV valves closing on the onset of ventricular systole
Second sound:
semilunar valves closing at the end of systole
What’s the difference between Left-Right and Right-Left congenital defects?
In Left-to-Right congenital defects blood flows backwards and fails to flow through systemic circulation.
-> Patent Ductus Arteriosis
In Right-to-Left heart failure the blood flows from right to left sides of the heart without going into the lungs.
-> Tetraolgy of Fallot
- in tetraolgy the septum/seperation between the ventricles
Doesn’t fully form and blood that’s supposed to go out the
pulmonary vein to the lungs goes out the aorta instead.
What is “circulatory shock”?
Circulatory shock is a general inadequate blood flow throughout the body, the tissues of the body are damaged because of overall lack of. Oxygen and nutrients delivery to the tissue cells.
Name two factors that severely reduce cardiac output.
What are some examples?
Factors:
- Cardiac abnormalities that decrease the ability of the heart to pump blood
- >Myocardinal infarction
- >Toxic state of the heart
- >severe heart vale dysfunction
- >heart arrhythmia
- >circulatory shock that results from diminished cardiac pumping ability is called cardiac shock. - Factors that decrease Venous Return
- > Diminished blood volume
- > decreased vascular tone (venous reservoirs)
- > obstruction of blood flow.
What negative feedback mechanisms attempt to return cardiac output and arterial pressure back to normal following cardiac shock?
Powerful sympathetic reflexes: by baroreceptors and other vasculalar stretch receptors
As a result of:
-decrease in arterial pressure after hemorrhage
-decrease in pressures in the pulmonary arteries and veins in the thorax
Effects
- arterioles constriction
- vein andvenous reservoirs constrict
- heart rate increase drastically
Cerebral and coronary vesssel remain normal unless pressure drops below 70mmHg
How do ADH, epinephrine and renin aid recovery from shock?
Secretion of renin and creation of angiotensin II causes the constriction of peripheral arteries and also decreased outputs of water and salt by the kidneys.
ADH also constricts arteries and veins, secreted by the posterior pituitary gland, and increases water retention in the kidneys
-AKA vasopressin
Epinephrine and norepinephrine from the adrenal medulla constricts peripheral arteries and veins and increases heart rate.
What are the competent army methods the body undergoes in order to return blood volume back to normal after circulatory shock?
- absorption of lots of fluid from the intestinaltract
- absorption of fluids into blood capillaries from the interstitial spaces
- water and salt retention by the kidneys
- Increase thirst and salt craving
Non-progressive shock vs. progressive shock
Non-progressive shock
- sympathetic reflexes and other factors compensate enough to prevent further deterioration of the circulation
- all these factors are negative eedback mechs that try to return cardiac output and arterial pressure back to normal
Progressive shock
- positive feedback
- when arterialpressure falls low enough,coronary blood flow decreases below thats required for adequate nutrition of the myocardium. heart muscle weakens and cardiac output deacreases
- depends on if hemorrhage is the cause
Lethal Progression of Shock
Vasomotor failure Blockage of small vessels Increase vascular permeability Release of toxins by necrotic tissue Cardiac depression causes by endotoxin Generalized cellular deterioration
