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Questions and Answers
What phase occurs when the ventricle applies pressure to pump blood?
What phase occurs when the ventricle applies pressure to pump blood?
What contributes to 80% of ventricular filling at rest?
What contributes to 80% of ventricular filling at rest?
What is the accurate marker for aortic valve closure?
What is the accurate marker for aortic valve closure?
What is primarily responsible for the secondary wave observed after the aortic valve closes?
What is primarily responsible for the secondary wave observed after the aortic valve closes?
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Which sound is associated with the closure of the atrioventricular valves?
Which sound is associated with the closure of the atrioventricular valves?
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What occurs during rapid filling of the ventricles?
What occurs during rapid filling of the ventricles?
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What is indicated by the presence of an S3 sound in adults?
What is indicated by the presence of an S3 sound in adults?
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What phenomenon is linked to decreased passive filling at higher heart rates?
What phenomenon is linked to decreased passive filling at higher heart rates?
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What factor primarily determines the delivery of oxygen and nutrients to tissues?
What factor primarily determines the delivery of oxygen and nutrients to tissues?
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During which phase does the ventricle not change its volume despite contracting?
During which phase does the ventricle not change its volume despite contracting?
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What is the approximate pulmonary artery pressure mentioned?
What is the approximate pulmonary artery pressure mentioned?
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What happens to the pressure in the ventricle as it begins to fill from point A to point B?
What happens to the pressure in the ventricle as it begins to fill from point A to point B?
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What is the term used for the phase when the ventricle relaxes but does not fill?
What is the term used for the phase when the ventricle relaxes but does not fill?
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Which of the following accurately describes end diastolic volume (EDV)?
Which of the following accurately describes end diastolic volume (EDV)?
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Which parameter is NOT directly measured within the ventricular pressure-volume loop?
Which parameter is NOT directly measured within the ventricular pressure-volume loop?
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What formula represents stroke volume (SV)?
What formula represents stroke volume (SV)?
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What is the minimum acceptable ejection fraction (EF) value for healthy function?
What is the minimum acceptable ejection fraction (EF) value for healthy function?
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How is ejection fraction typically used in heart failure assessments?
How is ejection fraction typically used in heart failure assessments?
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Which of the following conditions increases afterload?
Which of the following conditions increases afterload?
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Which parameter is not directly related to stroke volume?
Which parameter is not directly related to stroke volume?
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What occurs during the ventricular ejection phase from point C to point D?
What occurs during the ventricular ejection phase from point C to point D?
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How is cardiac output (CO) calculated?
How is cardiac output (CO) calculated?
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Which of the following factors directly affects preload?
Which of the following factors directly affects preload?
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Which statement about afterload is true?
Which statement about afterload is true?
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What does an increase in afterload typically lead to in terms of stroke volume and ejection fraction?
What does an increase in afterload typically lead to in terms of stroke volume and ejection fraction?
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Which factor is directly represented by the purple line in the ventricular pressure-volume loop?
Which factor is directly represented by the purple line in the ventricular pressure-volume loop?
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What is the significance of the area within the pressure-volume loop?
What is the significance of the area within the pressure-volume loop?
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How does increasing afterload affect myocardial oxygen demand compared to increasing inotropy?
How does increasing afterload affect myocardial oxygen demand compared to increasing inotropy?
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What does the term 'preload' specifically refer to in the context of ventricular function?
What does the term 'preload' specifically refer to in the context of ventricular function?
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Which variable is NOT a determinant of stroke volume in the pressure-volume loop analysis?
Which variable is NOT a determinant of stroke volume in the pressure-volume loop analysis?
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In the end-systolic pressure-volume relationship (ESPVR), what does a steeper line indicate?
In the end-systolic pressure-volume relationship (ESPVR), what does a steeper line indicate?
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What is primarily indicated by the myocardial oxygen demand during heart workload conditions?
What is primarily indicated by the myocardial oxygen demand during heart workload conditions?
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How does an increase in the radius of a ventricle affect wall tension?
How does an increase in the radius of a ventricle affect wall tension?
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What is the impact of increased wall thickness on wall tension?
What is the impact of increased wall thickness on wall tension?
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What effect does increased preload have on stroke volume?
What effect does increased preload have on stroke volume?
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What happens to ejection fraction as inotropy decreases?
What happens to ejection fraction as inotropy decreases?
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Which of the following best describes the relationship between increased afterload and stroke volume?
Which of the following best describes the relationship between increased afterload and stroke volume?
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What occurs during increased venous return in terms of preload and stroke volume?
What occurs during increased venous return in terms of preload and stroke volume?
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In the context of heart mechanics, how does an increased inotropy affect preload?
In the context of heart mechanics, how does an increased inotropy affect preload?
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Study Notes
Cardiac Cycle
-
Systole is the contraction phase of the heart:
- The heart chamber applies pressure to eject blood
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Diastole is the relaxation phase of the heart:
- The heart chamber does not apply pressure and fills with blood
Ventricular Pressure and Volume Curves
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Wiggers Diagram:
- Shows how ventricle can't eject blood into the arteries until ventricular pressure exceeds arterial pressure
- Shows ventricle can't accept blood from the atria unless ventricular pressure is lower than atrial pressure
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Valves:
- Ensure unidirectional blood flow despite significant pressure changes
Rapid vs Slow Ventricular Filling
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Rapid Ventricular Filling:
- Due to ventricle expansion and pressure drop
- Also known as passive filling, responsible for 80% of ventricular filling at rest
- Reduced at higher heart rates
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Slow Ventricular Filling:
- Occurs during atrial contraction, contributing to the final "bump" in volume
Aortic Pressure Curve
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Aortic Pressure:
- Oscillates between systolic and diastolic pressures
- Stays relatively high after aortic valve closure
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Dicrotic Notch:
- Division between the primary and secondary aortic pressure waves
- Most accurate marker of aortic valve closure
- Secondary wave likely due to aortic elastic recoil
Heart Sounds
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S1:
- Atrioventricular valve closure
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S2:
- Semilunar valve closure
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S3:
- Often found in healthy young adults and children
- New S3 in adults is usually pathological, indicating myocardial ischemia
- Blood enters a non-compliant ventricle during rapid filling
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S4:
- Typically pathologic
- Indicates ventricle straining as atria contract and force blood into a non-compliant ventricle
Right Side Heart
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Wiggers Diagrams:
- Right side of the heart shares similar principles but with lower pressures
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Pulmonary Artery Pressure:
- Roughly 25/7 mm Hg
-
Atrial Pressure:
- Slightly lower in the right atrium compared to the left atrium
Normal Cardiac Pressures
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Ventricular Pressures:
- Higher values represent peak pressures during ejection
- Lower values represent end-diastolic pressures
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Atrial Pressures:
- Represent values at the end of ventricular filling, just as atrial contraction is ending
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Arterial Pressures:
- Systolic/diastolic pressures
Cardiac Calculations and Parameters
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End Diastolic Volume (EDV):
- Volume in the ventricle at the end of diastole (around 120 mL)
-
End Systolic Volume (ESV):
- Volume in the ventricle at the end of systole (around 50 mL)
-
Stroke Volume (SV):
- Volume ejected with each heartbeat (SV = EDV - ESV) (around 70 mL)
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Cardiac Output (CO):
- Volume ejected per minute (CO = SV x HR)
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Ejection Fraction (EF):
- Proportion of EDV ejected per beat (EF = SV/EDV), should be at least 50%
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Preload:
- Volume in the ventricle before contraction (EDV)
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Contractility (Inotropy):
- Intrinsic ability of the cardiomyocyte to contract, dependent on calcium handling
-
Afterload:
- Pressure the heart must overcome to eject blood, increased by conditions like aortic stenosis or hypertension.
Pressure-Volume Loop of the Ventricle
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Useful for Measuring:
- Total cardiac workload
- Contractility
- Heart compliance
- Hemodynamic parameters (EDV, ESV, SV)
-
Curve Interpretation:
- A - Start of ventricular filling
- B - End of passive filling
- C - Isovolumic contraction
- D - Ejection phase
- A - Isovolumic relaxation
Pressure-Volume Loop Factors
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Slope of the Isometric Contraction Line:
- Represents contractility
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Distance between lines AD and CB:
- Represents stroke volume
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Point B:
- Represents preload (EDV)
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Tangent Line at Point D:
- Represents ESPVR (end-systolic pressure-volume relationship), indicating inotropy
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Purple Line:
- Represents afterload
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Area Within the Curve:
- Represents cardiac workload
Pressure-Volume Loop Workload
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Excessive Workload:
- Can lead to histological and molecular changes associated with heart failure
Pressure-Volume Loop Modifiers
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Increased Afterload:
- Higher aortic pressures, reduced SV, and ejection fraction, increased myocardial oxygen demand
-
Increased Preload:
- Higher EDV, increased SV
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Increased Contractility:
- Higher contractile force, decreased ESV, increased ejection fraction
Pressure-Volume Loop Interdependence
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Curve A:
- Increased venous return leads to increased preload and SV, with a slight increase in afterload due to increased wall tension
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Curve B:
- Increased afterload decreases SV and increases preload, establishing a new steady state with higher preload and greater afterload
-
Curve C:
- Increased inotropy increases SV and decreases ESV, leading to slightly lower preload
Modifiers of Cardiac Output
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Factors Affecting Cardiac Output:
- Preload
- Contractility
- Afterload
- Heart Rate
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Description
Test your understanding of the cardiac cycle, including the phases of systole and diastole, and the mechanics of ventricular pressure and filling. Explore concepts like the Wiggers Diagram and the functioning of heart valves. This quiz will challenge your knowledge on heart dynamics and blood flow.
