Lecture 13 Cardiac Failure, Heart Sounds, and Circulatory Shock Flashcards Preview

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Flashcards in Lecture 13 Cardiac Failure, Heart Sounds, and Circulatory Shock Deck (39)
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Define Cardiac Failure

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


Compensation for acute cardiac failure, effects of sympathetic innervation:

Strengthens muscle contraction (both undamaged and damaged)
Increases tone of most vessels, especially veins--> increases mean systemic filling pressure


Compensatory mechanisms by ANS for acute cardiac failure:

Baroreceptor reflex
Chemoreceptor reflex
CNS ischemic response


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

Sympathetic system strengthens this damaged musculature


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

The normal muscle is strongly stimulated


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

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


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

Reduced cardiac output
Damming of blood in the veins --> increased venous pressure


Pulmonary Edema and Left Heart Failure (wordy)

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.


Two major problems of left heart failure:

Pulmonary vascular congestion
Pulmonary edema


Conditions that result in High Output Cardiac Failure

Arteriovenous Fistula


Arteriovenous Fistula

Overloads heart because of excessive venous return
Venous return curve rotates upward (Fig. 22-8)



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)


First Heart Sound

AV valves close at the onset of ventricular systole


Second Heart Sound

Semilunar valves close at the end of systole


Valvular Defects

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


Describe Left-to-right shunt and give example

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


Describe Right-to-left shunt and give example

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


Define Circulatory Shock

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


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

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


Factors reducing cardiac output

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


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

Cardiogenic shock


Factors that decrease venous return:

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


Powerful sympathetic reflexes are initiated mainly by:

Arterial baroreceptors and other vascular stretch receptors


Powerful sympathetic reflexes result from:

Decrease in arterial pressure after hemorrhage
Decreases in pressures in the pulmonary arteries and veins in the thorax


Negative feedback mechanism reflexes result in three important effects:

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


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

Cerebral and cardiac vessels
70 mm Hg


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

See slides 61 and 62


Compensatory mechanisms that return blood volume back to normal:

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


Non-progressive Shock

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


Progressive shock

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