Exam #2: Cardiac Cycle Flashcards
During ventricular diastole, what is the state of the AV and SL valves?
AV valves are open and SL valves are closed
During ventricular systole, what is the state of the AV and SL valves?
AV valves are closed and SL valves are open
During ventricular diastole, within what part of the heart is pressure greatest and what does this mean for the state of the AV valves?
Atrial pressure is greater than ventricular pressure
- AV valves are open
- Blood is flowing from atria to ventricles
During ventricular systole, within what part of the heart is pressure greatest and what does this mean for the state of the AV valves?
Ventricular pressure is greater than atrial pressure
- AV valves are closed
During ventricular diastole, within what part of the heart is pressure greatest and what does this mean for the state of the SL valves?
Vessel pressure is greater than ventricular pressure
- SL valves are closed
During ventricular systole, within what part of the heart is pressure greatest and what does this mean for the state of the SL valves?
Ventricular pressure is greater than vessel pressure
- SL valves are open
- Blood flows from ventricles to rest of body
What are the seven phases of the cardiac cycle?
A. Atrial systole B. Isovolumic ventricular contraction C. Rapid ventricular ejection D. Reduced ventricular ejection E. Isovolumic ventricular relaxation F. Rapid ventricular filling G. Reduced ventricular filling
With atrial systole (phase A), which valves are open or closed?
- AV valves open
- SL valves closed
What EKG wave, heart sound and jugular pulse wave are seen during atrial systole (phase A)?
- P wave on EKG
- S4 heart sound
- A-wave of jugular pulse
How and when does MOST of the ventricular filling occur? What percentage of filling does atrial contraction account for?
MOST of ventricular filling occurs passively before atrial contraction
- Only 25% of atrial contraction accounts for ventricular filling at rest (40% during exercise)
When are ventricular blood volumes maximal during the cardiac cycle? What is this called?
Atrial systole (phase A) - End-Diastolic Volume (EDV)
With isovolumic ventricular contraction (phase B), which valves are open or closed?
ALL valves closed
What heart sound and jugular pulse wave are seen during isovolumic ventricular contraction (phase B)?
- S1 heart sound (LUB)
- C-wave of jugular pulse
What heart sound is the “lub”, and with which phase does it occur? What creates the sound (think valves)?
S1 heart sound during isovolumic ventricular contraction (phase B)
- Due to closing of AV valves
With rapid ventricular ejection (phase C), which valves are open or closed?
- SL valves open
- AV valves closed
During which phase is during maximal outflow velocity reached?
Rapid ventricular ejection (phase C)
When do the atria begin to refill with deoxygenated blood from the body via the vena cava?
Rapid ventricular ejection (phase C)
With reduced ventricular ejection (phase D), which valves are open or closed?
- SL valves still open
- AV valves remain closed
What EKG wave is seen during reduced ventricular ejection (phase D)?
T wave
During which two phases is there essentially a “delay” of activity within the ventricles? Describe this delay in each.
- Reduced ventricular ejection (phase D): delayed ventricular pressure decreasing - ventricular pressure decreases BUT SL valves are still open as blood is ejected to body due to inertial energy
- Reduced ventricular filling (phase G): delayed ventricular pressure increasing - as ventricles continue to passively fill with blood from atria, they become less compliant and ventricular pressure increases BUT AV valve is still open to allow continued filling
With isovolumic ventricular relaxation (phase E), which valves are open or closed?
ALL valves closed
What heart sound is heard during isovolumic ventricular relaxation (phase E)?
S2 heart sound (DUB)
What is the blood volume during isovolumic ventricular relaxation (phase E)? What is this called?
ESV = ~50 mL (blood volume is at its lowest)
What heart sound is the “dub”, and with which phase does it occur? What creates the sound (think valves)?
S2 heart sound during isovolumic ventricular relaxation (phase E)
- Due to closing of SL valves
With rapid ventricular filling (phase F), which valves are open or closed?
- AV valves open
- SL valves closed
What heart sound and jugular pulse wave are seen during rapid ventricular filling (phase F)?
- S3 heart sound
- V-wave of jugular pulse
With reduced ventricular filling (phase G), which valves are open or closed?
- AV valves still open
- SL valves remain closed
What is the longest phase of the cardiac cycle?
Reduced ventricular filling (phase G)
How does an increase in HR affect reduced ventricular filling (phase G)?
Increase in HR, decreases time available for this phase (Phase G)
- This in turn reduces/eliminates ventricular filling = reduced preload and stroke volume
What is stroke volume?
Volume of blood ejected with one ventricular contraction
How do you calculate stroke volume (SV)?
SV = EDV - ESV
What is ejection fraction?
Effectiveness of ventricles in ejecting blood
What does ejection fraction indicate?
Contractility
How do you calculate ejection fraction (EF)?
EF = SV/EDV x 100%
What is cardiac output?
Total volume of blood ejected per unit time
How do you calculate cardiac output (CO)?
CO = HR x SV
What is cardiac index?
CO normalized for body surface area
How do you calculate cardiac index (CI)?
CI = CO/SA
What does an S3 heart sound indicate?
Rapid ventricular filling
What is the S2 “physiological Split”?
A2 (aortic valve closing) then S2 (pulmonary valve closing)
How does inspiration affect the S2 split?
Inspiration increases A2-P2 split (makes it wider)
How does expiration affect the S2 split?
Expiration decreases A2-P2 split (makes it narrower)
What does a widened S2 split indicate in terms of ventricular function?
Delayed right ventricular emptying
What are three examples of potential causes for a widened S2 split?
- Pulmonic stenosis
- RV failure
- RBBB
What are two examples of potential causes for a narrowed S2 split?
- Aortic stenosis
- LBBB
What is a paradoxical S2 split?
S2 then A2
- Ex. Severe aortic stenosis
What is a systolic murmur associated with? When does a systolic murmur occur?
Systolic murmur: associated with ejection of blood through damaged valves during ventricular systole (contraction)
- Occurs after S1
What is a Mid-Systolic murmur due to?
SL valve stenosis
What is a Holosystolic murmur due to?
AV valve regurgitation
What is a diastolic murmur associated with? When does a diastolic murmur occur?
Diastolic murmur: associated with valvular issues during ventricular diastole (relaxation/filling)
- Occurs after S2
What is a Diastolic murmur due to?
AV valve stenosis
What is a Delayed Diastolic murmur due to?
SL valve regurgitation