cardiovascular physiology Flashcards
cardiac output equation
cardiac output = stroke volume x heart rate volume/min = (volume/beat) x (beats/min)
how does positive chronotropic stimulus affect cardiac output
increase heart rate (sympathetic) which increases cardiac output
how does postive inotropic stimulus affect cardiac output
increases stroke volume/contractility (sympathetic) which increases cardiac output
how does arterial pressure affect cardiac output
when arterial pressure is high it increases the afterload which decreases the stroke volume thus decreasing cardiac output
how does filling pressure affect cardiac output
when filling pressure is high (high preload) stroke volume increases (according to starlings law) and therefore cardiac output increases
chronological list events contractions and valve events
atrial contraction –> mitral close –> tricuspid close –> ventricle contraction begins–> pulmonic valve open –> aortic valve open –> aortic valve close –> pulmonic valve close –> tricuspid open –> mitral valve open
S1
atrioventricular valves closing “lub” sound immediately after QRS louder when: short PR, mild MVS, tachy softer when: AV block, mitral regurge, stiff LV
S2
semilunar valves closing “dub” sound after T wave, start of relaxation intesity varies based on: pressure gradient, muscle stiffness, valve radius, and blood viscosity
S3
result of ventricular overfilling: ventricular dilation and CHF SLOSH-ing-in (S1, S2, S3)
S4
result of low compliance of ventricle: hypertension, ischemia, outlet obstruction a-STIFF-wall (S4, S1, S2)
In a pressure volume loop like the one shown what does point 3 respresent
end diastolic pressure-volume relationship: indicates compliance
on a pressure-volume loop like the one pictured what does number 7 represent
end systolic pressure-volume relationship: indicated contractility
which number indicates the stroke volume
9 = stroke volume
what is occuring during 8 on the pressure-volume loop
isovolumetric relaxation
valves closed
what is happening during 4 on the loop
isovolumetric contraction
valves closed
what numbers represent the aortic valve opening and closing
5: AV valve opens
7: AV valve closes
what numbers on the loop indicate the mitral valve opening and closing
open: 1
close: 3
what occurs during 2 on the loop
ventricular filling, diastole
what occurs during 6 on the loop
ventricular emptying, systole
What do numbers 1-4 represent on the cardiac cycle graph
1: stroke volume
2: systolic pressure
3: diastolic pressure
4: aortic pressure
Status of the valves at each number 1-4
1: mitral valve close
2: Aortic valve opens
3. Aortic valve closes
4. Mitral valve opens
Label each of the heart sounds and describe the sounds
1: S4: caused by stiffening ventricle, decreased compliance
Atrial septal defect
symtpoms, physical exam findings, xray findings, echo findings
symptoms: slight murur, dyspnea on exertion, fatigue, frequent respiratory tract infections, tachycardia
physical exam findings: prominent systolic impulse palpatation, S2 widened with fixed split, systolic murmur upper-left sternal border: pulmonary valve, mid systolic murmur lower-left sternal border: tricuspid valve
xray: pruning of pulmonary vessels
echo: hypertrophy (the right ventricle chamber will be similar in size to left ventricle when it should be sibstantially larger)due to pulmonary hypertension
list pressures within each chamber of the heart
right atria: 2-8
right ventricle: 15-30/2-8
pulmonary artery: 15-30/4-12
left atria and pulmonary capilary wedge: 2-10
left ventricle: 100-140/3-12
aorta: 100-140/60-90
Frank-Starling law of the Heart
increases in fiber length will increase force of contraction/cardiac output
as endiastolic fiber length, volume, and pressure increase so do cardiac output, stroke volume, and stroke work due to optimal sarcomere overlap and increased calcium sensitivity
what is the red portion of the loop indicative of, explain changes in stroke volume and end diastolic pressure
decreased compliance (ventricular hypertrophy)
stroke volume decreases
end diastolic pressure increases
what condition could the red pressure volume loop indicate
how are stroke volume, end systolic volume, and end diastolic volume effected
mitral stenosis
decreased stroke volume
decreased end systolic volume (low afterload)
decreased end diastolic volume (decresed LV filling)
what does the shaded loop indicated
how are stroke volume, end systolic volume, end diastolic volume effected
mitral
stroke volume increased (increased compliance) *however, ejection into the aorta is actually decreased, the ventricular stroke volume is including the blood exiting the ventricle to both the aorta and atria
end systolic volume: decreases because takes both the blood entering the aorta and the atria into account
end diastolic volume: increases because the increased volume in the atria due to regurge is then sent into the ventricles
what could this pressure volume curve indicate
explain changes in stroke volume
end systolic volume and end diastolic volume and ventricular peak pressure
aortic regurgitation
stroke volume increases
end diastolic volume increases since blood backflows into ventricle
end systolic volume increases since not all blood is able to escape the ventricle
ventricular peak pressure increases because frank starling law, increased volume and stretching causes stronger contraction
Explain what could cause this tall T wave
in mitral regurgitation, backflow into the atria occurs during ventricular contraction causing an increase in pressure
what does PR interval indicate
time for action potential to conduct through AV node
what does P wave indicate
duration of atrial depolarization
what does the T wave indicate
ventricular depolarization
what does QT interval indicate
how long ventricles remain depolarized
what does QRS indicate
time for ventricular depolarization
TP interval
heart at rest and ventricles are filling
