Cardiac Cycle Flashcards
For which side of the heart is a Swan Ganz catheter used?
The right side
Where is a Swan Ganz catheter usually inserted and through which vessel does it enter the heart?
Usually inserted through the jugular vein and goes into the heart from the superior vena cava.
How is the pulmonary wedge pressure obtained and what is it typically used to measure?
Obtained when the Swan Ganz catheter is inserted all the way into the pulmonary circulation until it reaches a small capillary. A balloon is then inflated to block off pressure from the right ventricle so that the catheter tip can measure the pressure in the pulmonary vein - which is a good indicator of left atrial pressure.
For left ventricular catheterization, the catheter is usually inserted into the ______ artery and enters the heart through the _______.
inserted into the femoral artery, goes into the heart through the aorta.
What two pressures are of interest when performing left ventricular catheterization? Why?
Aortic pressure and left ventricular pressure because abnormal differences between the two indicate aortic valve pathology.
What are the seven phases of the cardiac cycle? Which ones correspond to systole and which ones correspond to diastole?
- Atrial systole
- Isovolumetric contraction
- Rapid ejection
- Reduced ejection
- Isovolumetric relaxation
- Rapid ventricular filling
- Reduced ventricular filling
#2 through 4 = systole #5 through 1 = diastole
What do the a, c, and v waves correspond to in an atrial pressure curve?
a wave is generated from atrial contraction.
c wave is due to the mitral valve ballooning back into the atrium during ventricular contraction.
v wave is due to slow atrial filling during systole and the first part of diastole.
What do the heart sounds S1 and S2 correspond to?
S1 corresponds to turbulent flow generated from closing of the mitral valve during ventricular contraction.
S2 corresponds to turbulent flow generated from closing of the aortic/pulmonary semilunar valves during ventricular relaxation.
What happens in between S1 and S2?
Ventricular systole
Why is the first phase of systole “isovolumetric?”
Because both the mitral valve and aortic valves are closed while the ventricles contract initially. Once pressure in the ventricle overcomes aortic pressure, the aortic valve will flip open, marking the beginning of the rapid ejection phase.
Does ventricular pressure rise or drop during rapid ejection?
It rises.
What accounts for “reduced ejection” despite the fact that the ventricles are relaxing?
The kinetic energy of the blood generated during rapid ejection keeps it out-flowing.
What is the dichrotic notch aka incisura?
A notch in the aortic pressure curve corresponding to the closing of the aortic valve. There is a drop in pressure during ventricular relaxation followed by aortic valve closure, followed by a slight increase in aortic pressure due to the abrupt stoppage of back-flowing blood. The low point in the curve is the notch.
What is end-diastolic volume?
Volume in the ventricles at the end of diastole.
What is end-systolic volume?
Volume leftover in the ventricles after systole.
