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30 Cards in this Set
- Front
- Back
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Blood flow through heart beginning with VC.
Compare pressures on each side of heart. |
VC==>RA-->RV-->PA-->PV-->LA--LV
P in R side of heart is low (2 mmHg) P in L side of heart is highest in LV (LA is pretty low) LV: 120/5 Ao: 120/80 |
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What is the primary pumping chamber of the heart?
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LV
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Cardiac Output = ?
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Cardiac Output = Stroke Volume (cc's per beat out of ventricle) x Heart Rate
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Blood Pressure = ?
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Cardiac Output x Systemic Vascular Resistance (presented by aa of body)
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If runner has increased blood flow during exercise, what is the effect on blood pressure?
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Although BP = Q x systemic vasc resist, BP stays the same, but systemic vascular resistance decreases--runners need to cool down so BP doesn't drop?
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What are the components of diastole?
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Isovolumic relaxation
Rapid Ventricular Filling (increase in volume) Atrial Contraction (kick) |
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Describe volumic changes during LV filling during the cardiac cycle.
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Systole: volume drops and stops
Diastole: rapid filling, nothing happens, and then more filling (atrial kick) |
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Systole begins with closure of the ___________
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mitral valve
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Diastole begins with closure of the ____________
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aortic valve
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What are the stages of systole?
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Isovolumic contraction (mitral and aortic valves closed), when LV Pressure exceeds aortic Pressure, aortic valve opens
[S1: closure of mitral and aortic valves] |
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S1 vs S2 events
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S1: mitral and tricupsid closure
S2: aortic and pulmonic closure |
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How does splitting of the second heart sound occur?
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Aortic valve closes before pulmonic closure and these events differ even more in time upon inhalation
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Events of systole vs events of diastole
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Systole:
Systole begins when mitral valve closes (triscupid valve closes too) Pressure builds with ISOVOLUMIC CONTRACTION Pressure opens pulmonic and aortic valves Ejection Diastole: Begins when aortic and pulmonic valves close As ventricles relax, pressure falls via ISOVOLUMIC RELAXATION When pressure low enough, mitral and tricuspid valves open Results in PASSIVE VENTRICULAR FILLING Followed by ATRIAL KICK |
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Compliance vs Stiffness
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Compliance: proportional to deltaV/deltaP (more compliant less of a change in P with a change in V; a good thing)
Stiffness: deltaP/deltaV |
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In a filling curve (P vs V), how would you identify a non-compliant LV?
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Higher change in Pressure for any given Volume (up and to the left)
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What are causes of diastolic dysfunction (stiffness)?
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LV Hypertrophy (chronic HTN, valvular heart dz, cardiomyopathy)
(anything causing LV to stretch or thicken) Myocardial ischemia or infarction |
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Preload vs Afterload
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Preload = Wall tension during diastole (ventricular filling)
Afterload = Wall tension during systole (ventricular ejection; EMPTYING) Where wall tension = P x radius (of sphere)/2h h=wall thickness |
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What is the most important determining factor of preload? Why?
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Pressure change during diastole is low, but volume change is huge so radius increases!
Wall tension = P x r/2h |
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What is the most important determining factor of afterload? Why?
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Systolic Pressure (BP)
As soon as mitral valve closes, pressure increases a lot |
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How can you increase preload? Decrease?
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Inc: Give fluid
Dec: Diuretic |
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How is afterload increased?
Decreased |
Any drug that increases, lowers BP
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Frank-Starling curves demonstrate what relationship?
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Preload on x-axis (LV End-Diastolic Pressure)
Cardiac output on y-axis As increase preload, cardiac output increases, but eventually levels off |
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As you increase LVDP, you increase ________.
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Stroke volume (cardiac output)
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How would a heart failure Frank-Starling curve appear?
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Would have decreased stroke volume (cardiac output) for a given LV EDP, so upon administration of fluid (to inc volume and then radius) wouldn't get as much of an inc'd output
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How is LA pressure measured?
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Catheterize pulmonary arteriole (Right side of heart) bc will measure Pressure of Pulmonary Vein which = LA pressure
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What does the Fick Method measure?
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Measures cardiac output
Done with Waters Hood |
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What is the Fick Principle?
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Higher cardiac output will result in higher venous oxygen saturation (less deoxygenated blood on return of RBCs to lungs)
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How is oxygen saturation of the pulmonary vein measured?
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Measure from any artery (only difference is oxygen taken by heart which is minimal)
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If the cardiac output is low, the mixed venous O2 content is __________ than normal.
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Lower than normal
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What happens to the Frank-Starling curve with a surge of epinephrine?
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Higher cardiac output, shift curve up and to left
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