7. Heart Failure Flashcards
Chronic heart failure is more prevalent in women. (T/F)
False: men
What disorders cause HF?
- ischemic heart disease
- HTN
- valvular heart disease
- other cardiomyopathies (less freqeunt)
Why does valvular dysfunction cause HF?
leaky valves over stress the heart muscle
What is the diagnostic criteria called for HF?
Framingham criteria
What are the major criteria of the Framingham criteria?
- nocturnal dyspnea
- neck vein distension
- pulmonary edema
- radiographic cardiomegaly
- hepatojugular reflux
What are the minor criteria of the Framingham criteria?
- bilateral ankle edema
- nocturnal cough
- dyspnea on ordinary exertion
- hepatomegaly
- tachycardia
Relaxation of the cardiac muscle cells is a passive process. (T/F)
False: active process
What are the major contractile proteins?
- thin actin
- thick myosin
Ca interacts with ________ to initiate muscle cell contraction.
troponin C
Ca enters cardiac myocyte through __________ channels.
voltage sensitive L-type
The entrance of Ca into cardiac myocyte triggers what?
release of Ca from sarcoplasmic reticulum
What uncovers sites on actin that bind myosin heads?
tropomyosin
What phase of the cardiac cycle occurs when the myosin heads flex?
systole
What happens when Ca is removed from troponin C binding sites?
- ends systole
- begins the diastolic phase of cardiac cycle
What factors strengthen muscle cell contraction?
- Ca concentration
- length of muscle fiber at end of diastole
Describe the pressure difference during systole.
Left ventricular pressure exceeds the atrial pressure
What valve closes during systole?
mitral
During what phase of the cardiac cycle is Ca taken up by the SR?
diastole
What is the preload?
load (blood) present before contraction
What occurs when preload is increased?
- ventricle distends during diastole
- HR ↑ because atrial mechanoreceptors ↑ the rate of SA node discharge
What is afterload?
systolic load on the left ventricle after it has started to contract
Where is afterload produced?
in te artery leaving the ventricle
What is the primary determinate of afterload?
total peripheral resistance
Why is an increased afterload detrimental?
It makes the heart work harder to push the blood out into the body
What is end systolic volume?
Blood volume remaining in the left ventricle at the end of systole
What is end diastolic volume?
volume of blood in the ventricle at the end of diastole
How do you find stroke volume?
EDV – ESV = SV
What is stroke volume?
Volume of blood ejected from the ventricle during systole
What is ejection fraction?
The percentage of ventricular volume expelled during systole
Systolic HF is an impaired _______ state.
inotropic
What characterizes systolic HF?
- inadequate cardiac output
- diminished expulsion of blood
What are the symptoms of systolic HF?
- cardiomegaly
- edema
- jugular venous distention
- left ventricular dilation
What is diastolic heart failure?
the reduced ability of the ventricles to accept blood
What characterizes diastolic HF?
- slowed or incomplete ventricular relaxation
- resting pressure in ventricle is ↑ : LV stiffness keeps the ventricle from filling properly
- SV is ↓ since filling volume is ↓
- ejection fraction may be normal
Left ventricular hypertrophy is greater with ______ HF.
systolic
Why does the heart remodel itself?
LV hypertrophy initially helps to maintain CO
Why is LV hypertrophy detrimental?
eventually the heart cells get so large and swollen that the contractile proteins do not overlap efficiently and over time, loses contractile function
Eventually, an enlarged heart cannot ____ properly and leads to _______ dysfunction.
- fill
- diastolic
What is the ryanodine receptor?
Ca release channel from sarcoplasmic reticulum
How is Ca actively taken up into the sarcoplasmic reticulum?
SERCA: sarcoendoplasmic reticulum Ca ATPase
In HF, Ca uptake by _______ is depressed.
SERCA
Right side HF is more common than left side HF. (T/F)
False: left is more common
What is right side HF?
Right ventricle cannot accept or eject the returning blood volume from the periphery.
What is the result of right side HF?
Blood backs up into the periphery
- capillary pressure in the periphery ↑
- results in loss of fluids to the tissues
In right side HF, edema is in response to stimulation of the _______.
RAAS
What is the primary characteristic of right side HF?
peripheral edema
In left side HF, the right side pumps normally so blood continues to go out to the lungs. (T/F)
True
Left side HF results in ______ blood volume in the lungs.
increased
What is the pulmonary impact of left side HF?
- ↑ pulmonary capillary pressure
- fluid filters out into lung interstitial space
- pulmonary edema (serious enough to cause death)
What are the pulmonary symptoms of left side HF?
- dyspnea
- orthopnea
- cough from pulmonary congestion
What are the 3 methods that the heart may use to adapt to maintain CO?
- Frank-Starling mechanism
- activation of neurohumoral systems
- myocardial remodeling
What is the Frank-Starling method?
an increased preload helps to sustain cardiac performance
What is the activation of neurohumoral systems?
- release of norepinephrine by adrenergic cardiac nerves
- activation of RAAS to maintain arterial pressure and perfusion to vital organs
What is myocardial remodeling?
mass of contractile tissue is increased
Which 2 cardiac adaptations occur rapidly?
- Frank-Starling mechanism
- activation of neurohumoral systems
What is Starling’s Law of the Heart?
Greater the heart is stretched during filling, the greater the force of contraction.
In a non-failing heart, an increased blood volume in, results in a normal volume pumped out. (T/F)
False: increased blood volume in, results in an increased volume pumped out
What is the compensation mechanism that leads to Na/water retention?
- ↓ renal perfusion
- aldosterone release
What is the compensation mechanism that leads to vasoconstriction?
↑ SNS activity
↑ Ang II
↑ vasopressin
What is the compensation mechanism that leads to tachycardia?
- ↑ SNS activity
- baroreceptor response to ↓ BP
What is the compensation mechanism that leads to ventricular hypertrophy?
↑ afterload
↓ CO
↑ preload
What is the compensatory benefit of Na/water retention?
↑ blood volume
↑ venous return, results in FS mech.
What is the compensatory benefit of vasoconstriction?
helps maintain BP when CO is reduced
What is the compensatory benefit of tachycardia?
helps maintain CO
What is the compensatory benefit of ventricular hypertrophy?
- helps maintain CO
- reduced myocardial wall stress
What is the adverse effect of Na/water retention?
pulmonary and systemic edema
What is the adverse effect of vasoconstriction?
↑ afterload
↑ myocardial oxygen demand
What is the adverse effect of tachycardia?
- ↑ myocardial oxygen demand
- arrhythmias
- β1 receptor down regulation
What is the adverse effect of ventricular hypertrophy?
- diastolic dysfunction
- hypertrophied ventricles - valve dysfunction
- arrhythmias
Why is maintaining arterial pressure an effective compensatory mechanism of ↓ CO?
allows limited CO to be most useful for survival
In HF, where does compensatory vasoconstriction mostly occur?
areas not vital for immediate survival
- skin
- skeletal muscle
- gut
- kidney
What vasoconstrictor systems increase in compensatory mechanism?
- SNS
- RAAS
- endothelin
Redistribution of blood maintains delivery of oxygen to what organs?
brain and heart
What is the primary stimulus to hypertrophy?
pressure overload
Increased ventricular wall stress leads to:
- thickening and elongation of individual myocytes
- replication of sarcomeres
- ventricular dilation
With chronic volume overload, ventricle becomes more _______ and causes _____ ______ defects.
- spherical
- mitral valve
A normal heart has a ______ force-frequency relationship.
positive
What is a positive force-frequency relationship?
the force of contraction and rate of tension development rise with ↑ stimulation frequency
cAMP __(↑/↓) activity of the Ca ATPase of the SERCA.
increases ↑
↑ Ca reuptake into the SR accelerates _______ _______.
diastolic relaxation
Heart failure creates a ______ force-frequecy relationship.
negative
In HF, disturbances in Ca concentrations __ (↑/↓) contractile function during myocardial failure.
reduce ↓
The Na/Ca exchanger in the cell membrane _______ Ca from the cytoplasm during diastole.
removes
In what way is the Na/Ca exchanger abnormal in HF?
expression is increased
Expression of the Na/Ca exchanger correlates ______ with the decrease in SERCA.
inversely
Why does Na/Ca exchanger increase as SERCA decreases?
compensatory response to the reduction in Ca reuptake by a decrease in SERCA
What is the benefit of increasing Na/Ca exchanger expression?
facilitates diastolic Ca removal
What is the adverse reaction of increasing Na/Ca exchanger expression?
increased potential for arrhythmias
Why does increasing Na/Ca exchanger expression increase potential for arrhythmias?
Ca efflux is associated with an influx of Na that prolongs depolarization and causes after-depolarization
What is NYHA Class I heart failure?
No limitation: ordinary physical activity does not cause undue fatigue, dyspnea, or palpitation
What is NYHA Class II heart failure?
- Slight limitation of physical activity: ordinary physical activity results in fatigue, palpitation, dyspnea, or angina
- comfortable at rest
What is NYHA Class III heart failure?
- Marked limitation of physical activity: less than ordinary physical activity results in symptoms
- comfortable at rest
What is NYHA Class IV heart failure?
- inability to carry out any physical activity without discomfort
- symptoms present at rest
