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What is the first heart sound from
Closing of the the mitril and tricuspid valves
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The second heart sound is made by
The closure of the Pulmonary and Aortic valves
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If there is a split of the S1 sound what could be the result
A conduction problem in the right bundle causing the left ventricle to fire first
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Physiologically which valve closes first
The aortic, only by a fraction of a second, not usually audibly distinguishable
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If there is a split in the S2 what is most likley happening
The Aortic valve is closing first (a deep breath can cause this)
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Where is the S2 heard best
At the base of the heart
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How does inspiration affect the heart sounds
Increased venous return to the right ventricle, it takes longer to empty, leading to an additional delay in closure of the pulmonic valve. (S2 sound)
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Pathological splitting of S2 may occur due to
Conduction anomalies, such as right bundle branch block or congenital defects such as atrial septal defect
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Where does an S3 sound come from on the cardiac cycle
It is at the beginning of the diastolic phase, or filling phase
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An S3 sound happens when a ventricle is
Overfilled
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What can cause an S3 sound
Over filling of the heart, or a leaky aortic or mitral valve
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What can cause an S4 sound
Reduced compliance of the heart
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When does an S4 sound occur in the cardiac cycle
Just prior to the systolic phase
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In what cases can an S3 sound occur in a healthy individual
Thin adults and children
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There is no physiological reason for what heart sound
S4
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S4 sounds are a result of what valve contraction
Atrial
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Chronic hypertension can cause what heart sound
S4
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What do you use to make sure the sound you are hearing is the systolic sound
Feel the patients pulse at the same time, the pulse coincides with the systolic, or first heart sound
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What is the difference between a murmur and a heart sound
A murmur is due to a leaky valve, heart sounds are from valves closing at abnormal times
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What is happening in the heart to cause an S4
The heart is unable to stretch further when the atrial contraction tries to put the last 10 ml's of blood in
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What causes an Aortic murmur
- Aortic stenosis produces a systolic murmur because there is a larger than normal pressure difference between the ventricle and aorta during systole, which forces blood through the
- narrowed aortic valve.
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Mitral regurgitation produces a systolic murmur due to
An leaky mitral valve allowing blood to regurgitate during systole from the high pressure ventricle through a narrow opening into the low pressure atrium.
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Mitral stenosis produces a diastolic murmur because
There is a larger than normal pressure difference between the atrium and ventricle during diastole, which forces blood through the narrowed mitral valve.
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Aortic regurgitation produces a diastolic murmur due to
Leaky aortic valve allowing blood to regurgitate (flow backwards) during diastole from the high pressure aorta through a narrow opening into the low pressure ventricle
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Concentric hypertrophy
Thickened ventricular wall with either an unchanged or reduced chamber diameter causing an S4 sound due to decreases compliance
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What can cause concentric hypertrophy
An increased afterload (pressure overload) for an extended period of time like chronic hypertension or aortic stenosis
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Eccentric hypertrophy
Thickening of the ventricular wall and increased ventricular chamber diameter causing an S3 sound
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What can cause eccentric hypertrophy
Volume overload (preload) for an extended period of time such as mitral valve regurgitaion or aortic valve regurgitation
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If there is no overfilling or change in the ventricular compliance, then there will be no
Heart sounds
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The SA node has how many beats a minute
60-100
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The AV node has how many beats a minute
40-60
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The bundle of His branch has now many beats per minute
20-40
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What is a P wave showing on an ECG
A wave of depolarization moving through the atria
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What is happening in the PR segment
A wave of depolarization moving through the AV, node, bundke of HIS, and purkinje system
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What is happening in the QRS section of an ECG
Ventricular depolarization
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What is going on in the T phase of an ECG
Ventricular repolarization
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What is the ST phase in an ECG
The ventricles are completely depolarized
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In an ECG what is the difference between a segment and an interval
A segment has no wave, an interval has to have a wave
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What is another name for the PR wave in an ECG
Atrioventricular conduction time
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What is the normal PR interval time
.12-.20 seconds
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If a PR interval time is above 20 seconds what is normally the cause
An AV conduction block
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What is the normal QRS time
Less then .10 seconds
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When heart cells are at rest, what charge is the membrane
The outside is positive relative to the inside
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The QT interval is less then
Half of one full interval
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What are the heart rates from the first cross section on
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