10 Questions
Which of the following is NOT a determinant of ventricular function?
Blood pressure
What is the primary function of the cardiovascular system?
Supply of oxygen and metabolic substrates
What is the formula for cardiac output (CO)?
CO = HR x SV
What happens to stroke volume (SV) as end-diastolic volume (EDV) increases, according to Starling's Law?
SV increases
What is the term for the period of rapid ventricular filling during diastole?
Rapid filling phase
What is the consequence of decreased ejection fraction (EF) in systolic dysfunction?
Increased left ventricular end-diastolic volume (LVEDV)
What is the primary difference between systolic dysfunction and diastolic dysfunction?
LV contraction is affected in systolic dysfunction, while LV relaxation is affected in diastolic dysfunction
What is the term for the maximum amount of blood ejected by the left ventricle during systole?
Stroke volume (SV)
What is the consequence of increased sympathetic stimulation on the Frank-Starling curve?
Shift to the left
What is the primary purpose of evaluating cardiac function?
To evaluate ventricular function
Study Notes
Cardiac Output and Function
- The cardiovascular system supplies oxygen and metabolic substrates to tissues and removes waste products, requiring integration of all its components.
- Most circulatory dysfunction in adults is due to abnormalities of the left ventricle (LV), making clinical evaluation of cardiac function focus on the LV's performance.
Determinants of Ventricular Function
- Stroke Volume (SV) is determined by preload, contractility, and afterload.
- Cardiac Output (CO) is determined by SV, Heart Rate (HR), synergistic LV contraction, LV wall integrity, and valvular competence.
- CO is calculated by multiplying SV and HR.
Cardiac Function Evaluation
- Myocardial function can be evaluated by preload, afterload, myocardial contractile state, HR, and cardiac rhythm.
- Chamber (LV) pump performance can be evaluated.
- Integrated cardiac function can be evaluated.
Starling's Law
- The law states that the force of contraction of the heart muscle depends on initial muscle fiber length.
- The greater the initial LV volume, the harder and faster the LV contracts and relaxes.
- As End-Diastolic Volume (EDV) increases, SV also increases.
Frank-Starling Curve
- The curve shows the relationship between EDV and SV.
- With sympathetic stimulation, there is a greater SV for the same EDV due to increased contractility.
Stages of Systole and Diastole
- LV Contraction (Systole) consists of isovolumic contraction, maximal ejection, and start of relaxation and reduced ejection.
- LV Relaxation (Diastole) consists of isovolumic relaxation, rapid LV filling, slow LV filling, and atrial systole.
Abnormal Cardiac Function
- Systolic Dysfunction: decreased Ejection Fraction (EF), increased LVEDV, and reduced SV due to problems with contraction.
- Diastolic Dysfunction: normal EF, increased LVEDV, and reduced SV due to problems with relaxation.
Cardiac Output
- Defined as the volume of blood pumped by each ventricle per minute.
- CO is calculated by multiplying HR and SV.
- Determinants of CO include HR, SV, and other factors affecting the heart's pumping ability.
- CO is a measure of the heart's effectiveness as a pump and indicative of total blood flow through the body.
This quiz covers the basics of cardiac output, ventricular function, and its determinants. Learn how the cardiovascular system works and how to evaluate cardiac function, focusing on the left ventricle's performance.
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