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41 Cards in this Set

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What is the equation for stroke volume?
Stroke vol = EDV - ESV
where
EDV is end diastolic vol (~120 ml)
ESV is end systolic vol (~50 ml)
What is the equation for ejection fraction?
EF = SV / EDV
where SV is stoke vol

eg EF = 70ml / 120 ml = 58%
What is the equation for cardiac output?
CO = HR * SV (per beat)
eg CO = 72beats/min * 70ml/beat = 5040ml/min = 5L/min
List two ways to increase SV (stoke vol).
1. Decrease the ESV
2. Increase EDV
How can you decrease ESV?
By increasing the contraction of the ventricles, the ESV is lower (and the SV is higher).
How can you increase the EDV?
By increasing the preload
Whats preload, and how can you increase it?
Preload is the volume of the ventricles at the end of diastole.
Increasing venous return increases the preload.
What normally happens to your ejection fraction if you preload increases?
It tends to stay the same.
eg 70/120 (58%) versus 87/150 (58%)
When do you see a decrease in the ejection fraction when preload increases?
During compensated heart failure.
eg 70/120 (58%) versus 70/150 (46%)
What causes a decrease in SV?
A higher afterload.
What is afterload, and what causes it to increase?
Afterload is the arterial/aortic pressure.
Ventricles must overcome the afterload to eject the blood out.
High blood pressure increases afterload.
How does high blood pressure lead to heart failure (eventually)?
High bp increases afterload so the heart has to work much harder to pump blood out, which cause hypertrophy and extra stress, both of which lead to failure.
List things that change the ESV.
1. Increased afterload increases ESV
2. Increased contractility decreases ESV
3. Increased preload increases ESV (eg 120-70 vs 150-87)
What things increase, decrease, or do not change the ejection fraction?
increase: inc contractility
decrease: compensated heart failure, inc afterload
remains the same: inc preload
List causes of increased contractility of heart?
1. athletes heart
2. Inc SNS
Why do athletes have lower heartrates?
Because they have higher stroke volume and normal cardiac output, so HR must decrease:
CO = SV * HR
CO tends to always be about 5L/min
List the ways that cardiac output is regulated.
1. Intrinsic regulation
2. SNS regulation
3. PSNS regulation
Describe intrinsic regulation.
Whatever blood is sent to the heart is pumped, according to the Frank Starling mechanism.
SV is proportional to EDV which is proportional to venous return.
What is the positive chronotropic effect?
The increase in heart rate by the SNS via the SA node.
Impulse received by B1 receptors.
What is a negative chronotropic effect?
The decrease in heart rate by the PSNS via SA node.
Impulse is sent via vagus nerve.
Describe physiological hypertrophy.
1. Enlarged heart
2. Seen in athletes
3. Higher contractile force results in higher ejection fraction due to more efficient heart.
Describe pathological hypertrophy.
1. Enlarged heart
2. Lower ejection fraction due to inefficient heart.
3. Causes: hypertension (chronically stresses heart), high afterload (same), poorly functioning valves
Whats another name for a heart attack, and the cause?
-Cardiac arrest.
-The heart has fibrilated (must be defibrilated).
Whats another name for compensated cardiac failure, and the cause?
-Congestive heart failure.
-Weak heart, CO decreases.
List symptoms of compensated cardiac failure.
-Shortness of breath
-Chronic cough (due to fluid in the lungs)
-May not "feel" any symptoms until they do exercise.
-No cardiac reserve.
-Venous return > CO (right atrial pressure exceeds 0mmHg, goes up to 6mmHg)
-Normalized stroke volume
-High end diastolic volume (due to high blood volume and venous return)
-Decreased ejection fraction
-Pathological hypertrophy
List the compensatory steps that occur in compensated heart failure.
When CO↓ (BP↓) :
1. ↑SNS (↑HR, ↑contractility, ↑venous return) (Short term).
2. BP↑ via salt and water retention by kidneys, this ↑blood volume which ↑venous return (Long term).
End result: These all stress the heart leading to pathological hypertrophy.
What is a positive inotropic effect?
The increase in heart contraction by the SNS.
Impulse received by B1 receptors.
Main difference between compensated and decompensated heart failure?
In decomp. the frank starling mechanism has broken down, and the normalized stroke volume cant be maintained, so CO drops and tissues/brain dont receive enough oxygen/nutrients.
List symptoms of decompensated heart failure.
-Low stroke volume
-Kidneys stop working/filtering
-Very high fluid retention
-Very high right atrial pressure
-Very high EDV (up to 300ml)
-Very low ejection fraction
-More pulmonary edema (usually leading to death)
Whats the treatment used for decompensated heart failure?
-Diuretics to reduce excess fluid
-Digitalis to strengthen the heart
List general differences between systolic and diastolic dysfunctions.
Systolic (emptying problem):
-↓EF
-↓CO
Diastolic (filling problem) :
-EF unchanged
-↓EDV and ↓SV
-↓CO
Is decompensated heart failure a diastolic or systolic dysfunction?
Systolic dysfunction, the heart has trouble emptying.
What is cardiac reserve?
The ability to increase your CO, eg during exercise.
List causes of heart valve lesions.
1. Congenital/birth defect
2. Streptococcal infection (eg rheumatic fever)
What is stenosis?
Heart valve doesnt fully open, eg pin hole.
Type of valve disorder with:
-Systolic dysfunction
-Aorta not opening properly
-Too much pressure in ventricle
-Systolic murmer
-Leads to LVH, ↓CO, pulmonary edema
AVS (aortic valve stenosis).
Type of valve disorder with:
-Systolic dysfunction
-Aorta not closing properly
-Too much volume in ventricle
-Diastolic murmer
-Leads to LVH, ↓CO, pulmonary edema
Aortic regurgitation
Type of valve disorder with:
-Systolic dysfunction
-Mitral valve not closing properly
-Too much volume in atrium and ventricle?
-Systolic murmer
-Leads to LVH, ↓CO, pulmonary edema, as well as RVH and atrial hypertrophy
Mitral regurgitation
Type of valve disorder with:
-Diastolic dysfunction
-Mitral valve not opening properly
-Underfilled left ventricle
-Diastolic murmer
-Leads to RVH, ↓CO, pulmonary edema, atrial hypertrophy, BUT NO LVH
Mitral stenosis
LVH, RVH, and atrial hypertrophy can lead to what?
Fibrillation.
Atrial hypertrophy leads to atrial fibrillation, not vent fib.
What is patent ductus arteriosis?
-The duct between the aorta and pulmonary artery never closed.
-Causes decreased CO due to dumpage of blood back in PA
-Murmer heard during systole and first part of diastole.