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QOD Exam 2 Questions And Correct Answers
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QOD Exam 2 Questions And Correct AnswersHow does hypertension affect afterload?
Afterload: resistance the heart must overcome eject blood from a given chamber.
HTN increases afterload bc the heart must generate more force to overcome the
increase in BP. This creates afterload for LV (systemic HTN) or RV (pulmonary HTN).
In aortic valve stenosis, the heart must generate more pressure to push blood through
the narrowed heart valve.
Why might someone with long-standing hypertension develop heart failure?
If the heart has to continually work against high BP, the heart will hypertrophy
(pathologic) to compensate, just like any other muscle that has to work against
increased resistance. This contributes to ventricular wall stiffness and decreased
chamber size. Both of these factors can contribute to diastolic dysfunction and heart
failure.
A patient has been diagnosed with left sided heart failure and an ejection fraction of
33%. What is the significance of this EF?
Ejection fraction tells us percent of EDV is pumped out of the heart with each beat,
related to cardiac output. A normal EF is somewhere between 55%-70%. A person with
an EF of 33% has systolic dysfunction. Results in a subsequent drop in cardiac output.
A patient has been diagnosed with left sided heart failure and an ejection fraction of
33%. How would this patient's left ventricular end-systolic volume (ESV) compare to
someone with a healthy heart?
ESV would be increased bc more blood would be remaining in the ventricle at the end of
systole. When the heart relaxes during diastole, the heart continues to fill as normal, and
the blood returning during diastole is added to the excess blood already in the ventricle.
, This will lead to increased ventricular pressures, which cause excessive stretch of the
ventricle. The increased stretch of the myocardium will lead the atria and ventricles to
release ANP and BNP respectively, which increase sodium (and therefore water)
excretion in the kidneys.
What is a valve stenosis and valve regurgitation (incompetence)?
Valve stenosis: thickened, stiff, scarred, or malformed valve that does not open fully.
Regurgitation is an "incompetent" valve that does not close fully.
How could valve disorders lead to heart failure?
Both stenosis and regurgitation disrupts unidirectional flow, leading to congestion in the
chambers and structures before the valve.
Aortic stenosis > blood backs up into LV > ventricle dilates and hypertrophies to
compensate, eventually become inadequate (remodeling of heart becomes pathologic)
> blood backs up into LA > blood backs up into lungs (pulmonary edema) and signs of
inadequate organ perfusion (dizziness, possible fainting, chest pain, low urine output,
diminished pulses, etc.)
With mitral stenosis or regurgitation, there is congestion in LA, hypertrophy, and
increased ESV. Why does LV have decreased ESV?
1. With mitral stenosis, less blood makes it into the left ventricle during filling, which
decreases end diastolic volume. If you start with less blood at the beginning of systole,
you will have less at the end of systole as well.
2. Mitral regurgitation reduces LV afterload. How? Because you essentially now have
two "doors" out of which blood can escape during systole (both the aortic valve and the
mitral valve are now allowing blood out during systole). Since blood is escaping out of
both valves, more blood is pumped out during systole, leading to a lower left ventricular
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