Cardiac Function and Indexing Concepts

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Questions and Answers

How is cardiac index calculated?

Cardiac output multiplied by body surface area

Cardiac output divided by body surface area (correct)

Cardiac output divided by blood volume

Cardiac output divided by body weight

What does the term 'indexed measurements' refer to?

Measurements that vary based on patient size (correct)

Measurements adjusted for age and gender

Measurements solely based on weight

Measurements standardized across all patients

Which statement best illustrates the concept of 'normal' in measurements?

Normal measurements are static and do not consider individual variability.

All patients should have the same measurements regardless of size.

Every patient must have the same cardiac output.

Normal measurements can differ based on body composition. (correct)

Why is cardiac output alone insufficient to assess heart function?

Cardiac output does not account for patient size. Signup and view all the answers

Which example best emphasizes the relativity of normal measurements?

A sumo wrestler's cardiac index compared to an average adult's. Signup and view all the answers

What is the definition of stroke volume?

The volume of blood ejected with each heartbeat Signup and view all the answers

During moderate to high heart rates, which factor limits stroke volume?

Insufficient filling time for the heart Signup and view all the answers

What is the average stroke volume for a person at rest?

70 - 100 mL Signup and view all the answers

How is stroke volume calculated?

EDV - ESV Signup and view all the answers

Which factor is unlikely to contribute to higher stroke volume?

Increased heart rate Signup and view all the answers

Katy has a higher stroke volume than Jessica primarily because:

Katy exercises regularly while Jessica does not Signup and view all the answers

What is the significance of EDV and ESV in relation to stroke volume?

EDV is the volume before contraction, while ESV is after, affecting stroke volume Signup and view all the answers

An elite athlete's stroke volume during cardio training can reach approximately:

150 - 220 mL Signup and view all the answers

What is considered a normal range for cardiac output (CO)?

4-8 l/min Signup and view all the answers

Which formula correctly represents the calculation for cardiac output?

CO = HR x SV Signup and view all the answers

When attempting to increase cardiac output during physical activity, which of the following actions may NOT contribute?

Decreasing heart rate Signup and view all the answers

What does the Mosteller formula calculate?

Body surface area Signup and view all the answers

What is the average body surface area (BSA) for an adult?

1.73 m² Signup and view all the answers

Which factors primarily influence an individual's body surface area (BSA)?

Height, weight, gender, and age Signup and view all the answers

In the equation CO = HR x (EDV - ESV), what do EDV and ESV stand for?

End-Diastolic Volume and End-Systolic Volume Signup and view all the answers

Which of the following actions would primarily increase stroke volume (SV)?

Increasing myocardial contractility Signup and view all the answers

What is the effect of the strain phase of the Valsalva Maneuver on cardiac output?

Decreases cardiac output Signup and view all the answers

What occurs during an inhalation of Amyl Nitrate?

Increased stroke volume Signup and view all the answers

Which maneuver is associated with a decrease in venous return?

Standing Signup and view all the answers

In which area of the heart are apical wall segments located?

At the tip of the ventricles Signup and view all the answers

What impact does inspiration have on cardiac parameters?

Increases venous return and cardiac output Signup and view all the answers

During the release phase of the Valsalva Maneuver, which of the following is true?

Cardiac output increases Signup and view all the answers

What is the correct relationship between the heart's walls and their respective segments?

Basal wall segments are closest to the atria Signup and view all the answers

Which of the following results from the inhalation of Amyl Nitrate?

Increased heart rate and decreased systemic resistance Signup and view all the answers

What is the primary function of the Autonomic Nervous System?

To respond to the metabolic needs of the body Signup and view all the answers

What is an example of a tissue controlled by the Autonomic Nervous System?

Heart Signup and view all the answers

Which description is associated with the Sympathetic Nervous System?

Increases heart rate during 'fight or flight' Signup and view all the answers

Which of the following best describes the Parasympathetic Nervous System?

Facilitates digestion and relaxation Signup and view all the answers

What is the main purpose of the Valsalva Maneuver?

To alter cardiac physiology Signup and view all the answers

During which phase of the Valsalva Maneuver does one bear down and hold their breath?

Strain Phase Signup and view all the answers

Which physiological response is most closely associated with a decreased heart rate?

Parasympathetic Nervous System activation Signup and view all the answers

What action should be taken during the Release Phase of the Valsalva Maneuver?

Breathe out normally Signup and view all the answers

What is the normal range for Cardiac Index (CI)?

3-4 l/min/m² Signup and view all the answers

Which formula correctly relates Cardiac Output (CO) to Stroke Volume (SV) and Heart Rate (HR)?

CO = SV x HR Signup and view all the answers

How is Stroke Volume (SV) determined based on the provided information?

SV = EDV - ESV Signup and view all the answers

What value did the calculation yield for the Cardiac Index (CI) in the example provided?

3.18 l/min/m² Signup and view all the answers

Which of the following factors does NOT influence Cardiac Output?

Respiratory Rate Signup and view all the answers

What is meant by the term 'Preload' in relation to Cardiac Output?

The amount of blood that stretches the ventricle during diastole Signup and view all the answers

If a patient has an End-Diastolic Volume (EDV) of 150 ml and an End-Systolic Volume (ESV) of 50 ml, what is the Stroke Volume (SV)?

100 ml Signup and view all the answers

What is the expected normal range for Cardiac Output (CO) in liters per minute?

4-8 l/min Signup and view all the answers

Study Notes

Cardiac Function Review

The heart's job is to pump enough oxygenated blood to the whole body. Supply and demand must be equal.
The heart's ability to achieve this depends on cardiac function, involving both systolic and diastolic components.
A normal heart should:
- thicken its walls concentrically during systole and thin/relax during diastole
- decrease in chamber size during systole and increase during diastole

Cardiac Output

Cardiac output is the volume of blood the heart pumps per minute.
It depends on heart rate (HR) and stroke volume (SV).
Cardiac output (CO) is calculated as CO = HR x SV.

Heart Rate (HR)

Heart rate is the number of heart beats per minute.
Normal range is 60-100 bpm.

Stroke Volume (SV)

Stroke volume (SV) is the amount of blood ejected from the ventricles with each heartbeat.
Normal range is 70-100 ml.
SV is calculated as SV= EDV-ESV
- EDV = end diastolic volume (largest volume of blood in the heart when diastole is finished)
- ESV = end systolic volume (smallest volume of blood in the heart when systole is finished)

Cardiac Output Equation

Cardiac output (CO) = heart rate (HR) x stroke volume (SV)

What does this all mean?

The body can increase cardiac output by increasing its heart rate and/or stroke volume.

Body Surface Area (BSA)

Body surface area (BSA) is a total surface area of the body, dependent on height, weight, gender, and age.
It's a more accurate indicator of body mass compared to body weight alone.
Average BSA is 1.73 m².
Mosteller formula is most common to calculate BSA.

Why is Body Surface Area relevant?

BSA is relevant for calculating indexed measurements, as "normal" is relative to patient size.

Cardiac Index (CI)

Cardiac index (CI) = Cardiac output (CO) / Body surface area (BSA)
It corrects CO for BSA, providing a more accurate measure for different patient sizes, normal range is 3-4 l/min/m².

Equations Recap

SV(ml) = EDV(ml)- ESV(ml)
CO(l/min) = SV(ml) x HR(bpm)
CI (l/min/m²) = CO (l/min) / BSA (m²)

Preload

Preload is the degree of ventricular muscle cell stretch at the end of diastole.
It depends on the end-diastolic volume (EDV).
Increased preload is due to higher end-diastolic volume and increased fluid overload. Examples include regurgitation and shunts.

Afterload

Afterload is the resistance the left ventricle must overcome to circulate blood.
Increased afterload can be due to hypertension and certain conditions affecting valve stenosis.

Inotropic and Chronotropic Force

Inotropic force is the strength of heart muscle contraction.
Chronotropic force is the rate of heart contraction.
- The autonomic nervous system (involuntary) influences both forces.

Autonomic Nervous System

The autonomic nervous system controls involuntary actions, like heart rate and glandular secretion.
It is divided into sympathetic and parasympathetic systems.

Sympathetic Nervous System

The sympathetic nervous system increases heart rate.
It's associated with the "fight-or-flight" response, increasing alertness in stressful situations.

Parasympathetic Nervous System

The parasympathetic nervous system decreases heart rate.
It's associated with the "rest-and-digest" response, allowing the body to relax and recover.

Maneuvers that alter Cardiac Physiology

Valsalva maneuver, Amyl Nitrate inhalation, and other methods can increase or decrease venous return, stroke volume, cardiac output, and heart rate.

Apical Wall Segments

Heart anatomy, especially the relative positions of segments.

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Description

This quiz explores key concepts related to cardiac index and output, emphasizing the significance of indexed measurements in heart function evaluation. It also addresses the relativity of 'normal' measurements in the context of cardiac health, enhancing your understanding of cardiovascular metrics.