VALVULAR DYSFUNCTION
MITRAL INSUFFICIENCY: Insufficiency
means the valve can't stay completely closed, so it is leaky. Mitral
Insufficiency causes fluid to reflux into the Left Atrium with each systole,
leading to a chronically high end-diastolic volume ------>
left-ventricular hypertrophy.
- Holosystolic Murmur can be heard
throughout systole, as turbulent blood flows through mitral valve.
- Third Heart Sound can be heard
during diastole, as there is a large excess of atrial blood ------>
turbulent flow during ventricular filling.
- Large V-Wave is seen: Higher
atrial pressure produced during diastole, because there is higher atrial
volume.
MITRAL STENOSIS: Leads to lower filling
of the left atrium, as the system backs up. This leads to overload of blood in
the pulmonary system.
- High Pulmonary Arterial Pressure
from backup of blood.
- Pulmonary Edema is a likely
complication that can result from the pulmonary hypertension.
- Right Ventricular Hypertrophy
also commonly comes from high Pulmonary hypertension.
- Heart Sounds:
- Pre-Systolic Crescendo Murmur
is diagnostic of mitral stenosis. The murmur results from large
increases of pressure during atrial systole, because of the
mitral stenosis.
- Diastolic (S3)
Decrescendo Murmur is also heard, as there is a large pressure
difference between atrium and ventricle during diastole. That pressure
difference then becomes smaller (i.e. quieter) as the ventricle fills
and the atrium empties.
AORTIC INSUFFICIENCY: Regurgitation
back into left-ventricle, on each systole, leads to severe left-ventricular
hypertrophy (when the insufficiency is severe).
- Dangerously Large Pulse Pressure
results from high systolic pressure (due to compensatory mechanism /
inotropic state), and markedly decreased diastolic pressure (due to low
stroke volume).
- High LVEDV ------> Left-Ventricular Hypertrophy
which can be severe.
- Heart Sounds:
- Loud Holo-Diastolic Decrescendo Murmur.
AORTIC STENOSIS: Very common in old
people.
- Severe Left Ventricular Hypertrophy.
The stenosis results in left ventricular pressure being a lot higher then
aortic pressure.
- HEART SOUND: Diamond-Shaped Pansystolic
Murmur -- i.e. diamond-shape = crescendo then decrescendo.
THE RIGHT HEART: Tricuspid and Pulmonic Valve problems
are similar to those found in the left heart.
MEASUREMENT OF CARDIAC OUTPUT (Last few pages of
handout):
- Direct Fick Method: You calculate
blood flow through the lungs (rate of O2 uptake) to determine the
pulmonary flow. Then you assume that pulmonary blood flow is equal to
systemic blood flow (i.e. CO).
- This assumption is true as long as there
are no intracardiac shunts.
- Indirect Fick (Thermal Dilution) Method:
Calculation blood flow essentially by measuring the time that it takes for
the flow of blood to neutralize a temperature difference between injected
saline and body temp.
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