Cardiac Muscle Dysfunction: Heart Failure Part 1 Flashcards
heart failure
- definition
- cardinal manifestations
- “heart failure” preferred over _____
complex clinical syndrome that results from any structural or functional impairment of ventricular filling or ejection of blood
manifestations
-dyspnea (need to consider DDx)
-fatigue
-fluid retention (variable)
heart failure preferred over “congestive heart failure”
heart failure
-clinical manifestations
marked decrease in exercise tolerance
decline in functional status
decrease in QOL
heart failure facts
- how common
- how much money
- prognosis
how common
-affects 5.7 million Americans
-550,000 new cases are diagnoses annually
how much money
-single most costly CV illness in US
-total treatment costs estimated at $30.7 billion annually
-compared to $132 minnion for lung cancer research (400,000 Americans)
prognosis
-one in 9 deaths list HF as contributing cause
-about 50% those diagnosed with HF die within 5 years
etiologies of HF
intrinsic cardiac disease
myocardial damage (post-MI) or s/p chemotherapy, radiation, drugs
excess work load
other
intrinsic cardiac disease specifics
coronary heart disease (CHD)
cardiomyopathy (CM)
valve disease
what can cause an excess work load on the heart
HTN
aortic stenosis
pulmonary HTN
other etiologies of HF
family history
chronic alcohol abuse
anabolic steroid - long term use
cardiomyopathy
-what happens?
heart muscle loses ability to pump effectively
heart becomes larger as it tries to compensate for its weakened condition
pathophysiology of HF
abnormal stroke volume due to
- impaired contractility
- increased afterload
- impaired ventricular filling
measurements of heart function
ejection fraction (LVEF) -normal 55-75% cardiac output -normal 4-8 L/min LVEDV or LVEDP echocardiogram exercise stress test
preload
- definition
- relation to HF
defines as “tension on muscle fibers at EDV”
can be abnormal in individuals with HF
heart can’t contract fully - get increased volume in ventricles
inotropic drugs
-what do they do
assist heart contractility
what happens to LVEDP and SV with a failing heart?
- add a diuretic
- add a vasodilator
- add a beta-agonist
LVEDP increases, SV decreases
diuretic
-decreases pressure the most, no effect on SV
vasodilator
-decreases pressure moderately, increases SV the most
beta-agonist
-decreases pressure the least, increases SV the most
how do the following affect factors that contribute to BF?
- diuretic
- vasodilator
- beta-agonist
diuretic -reduces preload vasodilator -afterload beta-agonist -increases inotropy
afterload and HF
- what is it
- afterload increases with
resistance encountered by LV when it tries to eject blood (systole)
afterload increased with increase in arterial vasomotor tone
increased afterload causes
increases myocardial oxygen consumption
-pumping against resistance
decreased stroke volume
in normal heart, increased afterload has little effect on SV
in HF< small increases in afterload can have big effects on SV
3 main types of cardiomyopathy
dilated
restrictive
hypertrophic
dilated CM
-what happens
muscle fibers stretch and heart chamber enlarges
-non-optimal length tension relationship
restrictive CM
-what happens
ventricle walls stiffen and lose flexibility
hypertrophic CM
growth and arrangement of muscle fibers are abnormal
heart walls thicken, especially in LV
preload increased
HF -systolic dysfunction
loss of contractility
dilated ventricle
increases LVEDV
leads to decreased EF
HF - diastolic dysfunction
impaired filling due to hypertrophy or decreased filling
results from HTN or aortic stenosis
sign of cardiac dysfunction
decreased ejection fraction
dilated CM effect on
- LVEDP
- force of muscle contraction
- systolic vs. diastolic
increase LVEDP
decrease force of muscle contraction
systolic
