CLASS 24 - HEART DISEASE Flashcards
What is the equation for cardiac output?
HR x SV
What is the purpose of cardiac compensation?
To increase cardiac output.
What are the 4 mechanisms of cardiac compensation? Which system controls each mechanism?
1) go faster (SNS, increased HR)
2) squeeze harder (SNS, increased contractility)
3) fill up more (RAAS, increased preload)
4) carry more stuff (EPO, increased hb, rr, oxygen)
what are the negative effects on the heart due to cardiac compensation mechanisms
1) go faster
2) squeeze harder
3) fill up more
4) carry more stuff
1) go faster - increased workload
2) squeeze harder - hypertrophy
3) fill up more - dilation + stretch
4) carry more stuff - polycythemia
what is cor pulmonale?
hypertrophy of the RV as a result of disease of the lungs or pulmonary blood vessels.
What are the 4 types of cardiac remodelling?
dilation
hypertrophy
cardiomegaly
cardiomyopathy
what are the negative effects of dilation on the heart?
elongated cells w baggy walls
decreased starling response
larger size of heart w slightly thicker walls.
what is hypertrophy?
overgrowth, thick cells, thick walls, smaller cavity
what is cardiomegaly?
a big heart.
what is cardiomyopathy?
disease of all heart muscle (global)
what is cardiac de-compensation?
what does it result in?
heart “failure”
- myocyte loss therefore heart is stiff + weak
- hgher heart tissue oxygen demand in thick + elongated myocytes
- inefficient pumping due to decreased CO
- prone to arrythmias
what causes cardiac hypertrophy? what are the 2 loads that cause cardiac hypertrophy?
increased workload on the heart .
pressure overload + volume overload
what is physiological cardiac hypertrophy?
what is pathological hypertrophy?
when the heart hypertrophies in response to a physiological stimulus such as aerobic exercise or strength training.
when the heart hypertrophies in reponse to a disease process.
what are the effects of pressure overload on the heart? what are some examples of pressure overload?
thicker ventricle wall, reduced chamber volume
examples: hypertension, aortic stenosis, strength training.
what are the effects of volume overload on the heart? what are some exampes of volume overload?
enlarged chamber size, small increase in wall thickness
ex - aortic regurgitation, aerobic training
identify the 9 acute stressors on the heart that immediately result in a decreased CO.
1) Arrythmias
2) Chemotherapy
3) Pregnancy
4) Pulmonary Embolism
5) Ruptured Papillary Muscle
6) Thyrotoxicosis
7) Hypertension Crisis
8) Myocarditis
9) MI
What are the 7 stressors on the heart that lead to the slow developent of long-term heart failure?
1) Ischemic Heart Disease
2) Hypertension
3) DM
4) Pulmonary Disease
5) Valvular Disease; endocarditis
6) Anemia
7) Cardiomyopathy
What is systolic dysfunction?
Heart fails to generate enough force to adequately pump blood, resulting in decreased contractility and SV.
What is diastolic dysfunction?
Reduced ability of ventricles to fill. Can occur due to failure of the myocardium to relax, or due to increased stiffness of the ventricle.
Why do systolic and diastolic dysfunction often occur together?
Which is responsible for the “forward” manifestations of HF? “Backward” manifestations?
bc if the heart can’t fill properly, it also cannot pump adequate blood. A heart that doesn’t pump blood adequately becomes overfilled.
systolic: forward
diastolic: backward
What is the formula for ejection fraction (EF)?
EF = SV / EDV
What are the main tools used to measure EF?
ECHO
MRI
Angiogram
What is the EF used for?
Used to grade function of the ventricles.
What do the following EFs indicate?
- 60% or higher
- 40-59%
- 20-39%
- less than 20%
- 60% or higher: NORMAL
- 40-59%: MILD dysfunction
- 20-39%: MODERATE dysfunction
- less than 20%: SEVERE dysfunction
What is HFrEF?
Heart Failure w Reduced Ejection Fraction
Describe HFrEF in terms of systolic function, EF, and its effects on the heart.
- reduced systolic function
- EF lower than 50%
- unable to overcome SVR
- loss of muscle cells
- decreased contractility
- structural changes
- high afterload
What is HFpEF?
Heart Failure with Preserved Ejection Fraction.
Describe HFpEF.
HF symptoms with EF greater than 50%
component of diastolic HF
“stiff” ventricle, shifts pressure-volume curve
diminished relaxation in early diastole, diminished compliance (stretch) in late diastole
impaired filling during diastole
- high filling pressures
- venous engorgement (transmits backward)
limits CO
decreased activity tolerance