Lecture 15: Cardiac Failure, Heart Sounds, and Circulatory Shock Flashcards
What is cardiac failure?
failure of the heart to pump enough blood to satisfy the needs of the body
How does the ANS compensate for acute cardiac failure?
baroreceptor reflex
chemoreceptor reflex
CNS ischemic response
In acute cardiac failure, if all the ventricular musculature is diffusely damaged but still functional, ________ strengthens this damaged musculature
sympathetic strengthens
If part of the musculature is nonfunctional and part is still normal, the normal muscle is ______
strongly stimulated
Strong sympathetic stimulation increases tone of most of the blood vessels in circulation and therefore increase ______
venous return
What are the acute effects of a heart attack?
reduced cardiac output
damming of blood in the veins—increased venous pressure
In an acute heart attack, what does the compensation?
sympathetic nervous system
What are the chronic compensations after an acute heart attack?
- results for partial heart recovery and rental mention of fluid
- max pump ability is depressed to less than one half normal
- any heavy exercise causes immediate return to symptoms of acute failure
- increase in right atrial pressure can maintain cardiac output near normal level
In left heart failure, blood pumps into the lungs but ______
not adequately out of them
If blood cannot be pumped out of the lungs, what happens?
mean pulmonary filing pressure rises because of shift of large volumes of blood from the systemic circulation into the pulmonary circulation
pulmonary capillary pressure increases
What are the two major problems with left heart failure?
pulmonary vascular congestion
pulmonary edema
In severe acute left heart failure, pulmonary edema may happen so rapidly that it can cause death by ______ in _____ minutes
suffocation, 20-30
What does an arteriovenous fistula do?
overloads heart because of excessive venous return
venous return curve rotates upward
What is beriberi?
thymine deficiency that leads to weakening of the heart
decreased blood flow to kidney — fluid retention
increased mean filling pressure
venous curve shifts to right
_______ results in major decrease in peripheral vascular resistance
AV fistula
What is the first heart sound?
AV valves close on at the onset of ventricular systole
What is the second heart sound?
semilunar values close at end of systole
What is a left to right congenital defect?
blood flows backward and fails to flow through systemic circulation
What is right to left congenital defect?
blood flows from right to left side of heart, bypassing lungs
What type of defect is ductus arteriosus?
left to right
What type of defect is tetralogy of fallot?
right to left
What is the definition of circulatory schock?
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
What are some cardiac abnormalities that decrease the ability of the heart to pump blood?
myocardial infarction toxic state of the heart severe valve dysfunction heart arrhythmias circulatory shock
What are factors the decrease venous return?
diminished blood volume
decreased vascular tone
obstruction of blood flow
What are powerful sympathetic reflexes initiated by?
arterial baroreceptors and other vascular stretch receptors
What does powerful sympathetic reflexes result from?
decrease in arterial pressure after hemorrhage
decreases in pressures in the pulmonary arteries and veins in the thorax
What effects result from powerful sympathetic reflexes
arterioles constriction in most parts of the systemic circulation
veins and venous reservoirs constrict
heart activity increases markedly
Compensatory mechanisms that return blood volume back to normal after shock
absorption of large quantities of fluid from intestinal tract
absorption of fluids into blood capillaries from the interstitial spaces of the body
conservation of water and salt by kidneys
increased this and appetite fro salt
What is non progressive shock?
sympathetic reflexes and other factors compensate enough to prevent further deterioration of the circulation
negative feedback mechanisms
What is progressive shock?
positive feedbacks
when arterial pressure falls low enough, coronary blood flow decreases below requirement for nutrition of the myocardium
What is one of the important features of progressive shock?
whether or not it is hemorrhagic in origin
What are the factors in final lethal progression of schock?
vasomotor failure blockage of small vessels increased vascular permeability release of toxins by necrotic tissue cardiac depression caused by endotoxin generalized cellular deterioation
What is neurogenic shock?
shock occurring from any loss of blood volume
What are the causes of neurogenic shock?
deep general anesthesia
spinal anesthesia
brain damage
