L16: Cardiac Failure, Heart Sounds & Circulatory Shock Flashcards
define cardiac failure
failure of heart to pump enough blood to satisfy needs of the body
compensation for acute cardiac failure
–sympathetic stimulation
strengthen contraction
increases tone of vessels = increased mean systemic filling pressure
normal CO and right atrial pressure
Co = 5 L/min rap = 0 mmhg
right atrial pressure _____ when the heart experiences damage.
increases
due to retention of fluids - edema
ANS mechanisms for acute cardiac failure
baroreceptor, chemoreceptor reflexes and CNS ischemic response
during heart failure: blood continues to be pumped _____ the lungs, but it is not …. ?
into
not adequately pumped out of lungs = pulmonary edema
2 major problems of left heart failure
- pulmonary vascular congestion
2. pulmonary edema
in _________ , pulmonary _____ can occur so rapidly that it can cause death by suffocation in 20-30 minutes.
severe acute left heart failure
pulmonary edema
after moderately severe heart attack: CO and RAP #’s
CO = 2 L/min (5) RAP = 5 mmhg (0)
30 seconds after a moderately severe MI
CO = 4 RAP = 5
after sympathetic activation response
one week after a moderately severe MI
CO = 5 RAP = 6
represents a return to normal but have a damaged heart that the sympathetic system is keeping going
graphical analysis of decompensated heart disease
progressive shift of venous return curve to right due to continued fluid retention
CO tries to increase to normal but fails and drops back below 1 L/min
RAP is increasing the entire time
digitalis function
works on a chronically failing heart
- -by increasing conc. of Ca ions in muscle fibers
- -thus increasing strength of contraction
arteriovenous fistula
- high CO failure
- overloads heart because of excessive venous return
- venous return curve, rotates upward
Beriberi
- high CO failure
- thiamin deficiency
- decreased blood flow to kidneys causing fluid retention
- thus increases mean filling pressure
- venous return curve shifts to right
AV fistula results in a major _____ in ______ .
decrease
peripheral vascular resistance
beriberi results in a _______ of the heart due to ______ . Which leads to ______ blood flow to kidneys and _______ of fluid.
weakening
lack of thiamine
decreased
retention
first heart sound
- AV valve close at onset of ventricular systole
mitral/tricuspid valves
second heart sound
- semilunar valves close at the end of systole
list some valvular defects
- valvular lesions
- rheumatic valvular lesions
- heart murmurs
- aortic stenosis
- mitral regurgitation
- mitral stenosis
left to right congenital defects
–blood flows backward and fails to flow thru systemic circulation
right to left congenital defects
- -blood flows from right to left side of heart
- -bypassing lungs
ductus arteriosus
- -a connection between pulmonary art. and underside of aorta
- -necessary for fetus but bad after birth but takes a few days to shut down
–should just be a fibrous connection in adults
patent ductus arteriosus
- -ductus arteriosus never broke down
- -can be surgically tied off
- -unfixed it allows some deoxygenated blood to enter aorta and into systemic circulation
tetralogy of fallot
- -mostly due to failure of ventricles to fully separate
- -patent ductus arteriosus
- -aorta shifted to be in between ventricles and not over left
tetralogy refers to four defects occurring at once
3 listed above
define circulatory shock
generalized inadequate blood flow thru the body
to the extent that the body tissues are damaged
especially due to too little O2, nutrients delivered to cells
list some cardiac abnormalities that decrease ability of heart to pump blood
- MI
- toxic state
- heart valve dysfunction
- arrhythmias
- circulatory shock
cardiogenic shock
circulatory shock due to diminished cardiac pumping ability
list some factors that decrease venous return
- diminished blood vol.
- decreased vascular tone
- obstruction of blood flow
what initiates powerful sympathetic reflexes
- arterial baroreceptors/ stretch receptors
- –decrease in arterial pressure after hemorrhage
- –decreases in pressures in pulmonary arteries and veins in thorax
3 important effects of sympathetic reflexes
- arterioles constrict in most of systemic circulation
- veins and venous reservoirs constrict
- HR greatly increases
factors that cause a person to recover from moderate degrees of shock
- baroreceptor reflexes
- CNS ischemic response
- reverse stress-relaxation of circulatory sys.
- increased secretion of renin by kidneys
- increased secretion by post. pituitary gland of vasopressin
- increased secretion by adrenal medulla of epine.
CNS ischemic response
creates more powerful sympathetic stim. thru out body
not activated until arterial pressure is below 50
reverse stress-relaxation of circulatory system
causes BVs to contract around diminished blood vol. so that blood vol. that is available fills circulatory sys.
vasopressin
ADH
recovery from shock by GI
absorption of large volumes of fluid
recovery from shock by capillaries
blood capillaries absorb fluids from intercell space
recovery from shock by kidneys
conserve water and salt
brain increases thirst and appetite for salt
non-progressive shock
sympathetic reflexes and other factors compensate enough to prevent further deterioration of circulation
negative feedback
progressive shock
- -positive feedback
- -arterial press. falls low enough that coronary blood flow decreases below required amount
- –heart weakens and decreased CO
one of the important features of progressive shock is ?
whether or not it is from hemorrhage
neurogenic shock definition
shock occur w/o loss of blood volume
neurogenic shock mechanism
vascular capacity increases so much that normal blood amount is not capable of filling circulatory sys.
neurogenic shock causes
- sudden loss of vasomotor tone = massive dilation of veins
- deep general anesthesia
- spinal anesthesia
- brain damage
deep general anesthesia
depresses vasomotor center enough to cause vasomotor paralysis
spinal anesthesia
blocks sympathetic nervous outflow
brain damage
causes vasomotor paralysis
