17 Questions
What is the correct sequence of events during the cardiac cycle?
Systole, diastole, systole
What is the normal peak pressure in the left ventricle during systole?
120 mm Hg
What is the relationship between S3/S4 heart sounds and heart disease in adults over 40?
S3 and S4 are pathologic and correlate with heart failure and myocardial ischemia
What is the cause of the S3 heart sound?
Abrupt deceleration of inflow across the mitral valve
What is the cause of the S4 heart sound?
Increased left ventricular end diastolic stiffness which decreases compliance
During which phase of the cardiac cycle are the aortic and pulmonic valves closed and the mitral and tricuspid valves open?
Diastole
What is the purpose of atrial contraction during the cardiac cycle?
To increase ventricular filling and stroke volume
What is the significance of the splitting of the second heart sound (S2)?
It indicates a delay in the closure of the pulmonic valve compared to the aortic valve
What is the main difference between the pressures in the right and left sides of the heart?
Right-sided pressures are lower than left-sided pressures
During which phase of the cardiac cycle does atrial contraction occur?
Late ventricular diastole
What is the purpose of the fourth heart sound (S4)?
It indicates the atrial contraction during late diastole
What event produces the second heart sound (S2)?
Closure of the aortic valve
During diastole, what event allows blood to flow from the left atrium to the left ventricle?
Opening of the mitral valve
What is the cause of the third heart sound (S3) in children and young adults?
Rapid deceleration of blood against the ventricular wall
What does the presence of a fourth heart sound (S4) in older adults typically indicate?
A pathologic change in ventricular compliance
During which phase of the cardiac cycle does the mitral valve open?
Diastole
What event immediately precedes the first heart sound (S1) of the next cardiac cycle?
Atrial contraction
Study Notes
Cardiac Cycle
- The heart serves as a pump that generates varying pressures as its chambers contract and relax.
- Systole is the period of ventricular contraction, during which pressure in the left ventricle rises from less than 5 mm Hg to a normal peak of 120 mm Hg.
- Diastole is the period of ventricular relaxation, during which pressure in the left ventricle falls.
Valves and Blood Flow
- The aortic and pulmonic valves are closed, and the mitral and tricuspid valves are open during diastole.
- The aortic valve closes, producing the second heart sound, S2, and another diastole begins.
- The mitral valve opens, allowing blood to flow from the left atrium to the left ventricle, and may be audible as a pathologic opening snap (OS) if valve leaflet motion is restricted.
Heart Sounds
- S1 is the first heart sound, occurring during systole, and is produced by the closure of the mitral and tricuspid valves.
- S2 is the second heart sound, occurring during diastole, and is produced by the closure of the aortic and pulmonic valves.
- S3 is the third heart sound, occurring during early diastole, and is produced by rapid deceleration of the column of blood against the ventricular wall.
- S4 is the fourth heart sound, occurring during late diastole, and is produced by atrial contraction.
Pathologic Changes
- In most adults over 40 years, S3 and S4 are pathologic and are correlated with heart failure and acute myocardial ischemia.
- S3 may indicate a pathologic change in ventricular compliance, and is sometimes termed "an S3 gallop".
- S4 may also indicate a pathologic change in ventricular compliance.
Learn about diastolic heart sounds S3 and S4, their correlation with heart failure and acute myocardial ischemia, and their pathologic significance in adults over the age of 40. Explore the characteristics of S3 and S4, as well as their association with mitral valve deceleration and left ventricular end diastolic stiffness.
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