PSL301: Cardio 4 Flashcards
First heart sound
“lub”
Closing of AV valves
Second heart sound
“dup”
Closing of semilunar valves
Ausculation
Listening to heart
What might cause a leaky aortic valve?
Calcification of aortic walls (hardening)
What happens when the valves don’t close properly?
Blood leaks backwards
When the aortic valve doesn’t fully close, what sound is made?
sloshing sound
Aortic regurgitation
Leaking aortic valve (backflow into left ventricle)
Aortic regurgitation seen on PV loop
- Pressure same as normal
- Vol increased
Aortic stenosis
Opening of aortic valve is narrower
Aortic stenosis seen on PV loop
- Volume same as normal
- Pressure increased
2 phases of cardiac cycle
- diastole
2. systole
How does systole pump blood?
Contraction raises pressure
Blood flows down pressure gradient
Events on the right & left side of the heart are the ___, but pressure are lower on the ___
Same
Right
ESV =
end systolic volume
65 mL
EDV =
end diastolic volume
135 mL
How much blood we are moving (CO) depends on…
- HR
- Stroke vol
Formula: SV
SV = EDV - ESV
Usually 70 mL
Inotrope
Agent that alters the force or energy of muscular contractions
How to maximize SV?
Higher EDV
Lower ESV
(this maximizes the difference)
Increase preload causes SV to…
Explain
Go up
Higher EDV
Define: SV
amount of blood pumped by 1 ventricle in 1 contraction
Formula: CO
CO = HR x SV
Define: CO
amount of blood pumped per ventricle per unit time
Unit for CO
L/min
Unit for SV
mL/beat
What is the normal CO?
5L/min
What is normal blood volume?
5L
Cardiac reserve is the difference between ___ and ___ CO
Resting
max
What does Frank-Starling Law of the Heart ask?
What affects stroke volumes?
What affects stroke volume?
- Preload (mostly)
- Afterload
Preload
Pressure at the end of diastole
Afterload
Pressure during ventricular contraction
What increases SV?
Increased EDV Exercise (increase venous return) Slow HR (allow more to fill)
What decreases SV?
Blood loss
Rapid HR (no time to fill)
Decreased EDV
Frank-Starling Law of the Heart states that…
SV increases as EDV increases
EDV is affected directly by…
Venous return
Venous return is directly affected by
- skeletal muscle pump
- Respiratory pump
- SNS
Force of contraction of heart is affected by…
EDV
Contractility / length of muscle fibre
The Starling curve shows..
relationship between stretch (EDV) & force (SV)
Increased stretch = increased pressure
Increased EDV = increased SV
How does increased EDV lead to increased SV?
EDV stretches the sacromere out more
What happens to the Starling curve as intensity of exercise increases?
Becomes higher; bigger slope
Same EDV = higher SV
What happens when EDV is too high?
Sacromeres stretch too much = left ventricle dysfunction
Example of inotrope
NE
How does NE affect contractility of the heart?
Starling curve looks like exercise
Same EDV = higher SV
Increase contractility
are NE and E positive or negative inotropes?
Positive (increase contractility)
Negative inotropes ___ contractility
decrease
Examples of negative inotropes
- B-blocker
- Ca channel blocker
What is the purpose of negative inotropes?
- Decrease risk of second MI
- Hypertension
Contractility is independent of…
- stretch
- EDV
Increase in contractility comes from…
- Sm stimuli
- Hormones
- more Ca++
- Drugs
Define: contractility
increase in contractile strength
SNS ___ venous contraction
increases
How does Sm NT affect contractility?
Bind to B1 G-proteins -> cAMP & PKA
More Ca++ binding to troponin
High blood pressure ___ SV
decreases
Only ___ affect the HR
- SNS
- PNS
