Cardiac Cycle, Cardiac Performance, Preload and Afterload Flashcards
At what point during the cardiac cycle are all four valves shut?
Isovolumic contraction
What is the dichrotic notch?
Point on the graph in which pulmonary and aortic valves close
What causes the dichrotic notch?
Decrease in pressure due to blood flowing back onto the aortic valve and into the coronary arteries
What does the dichrotic notch signify in the cardiac cycle?
End of ventricular systole
What are the 6 steps in cardiac cycle?
Diastole Systole Isovolumic contraction Rapid ejection Reduced ejection Isovolumic relaxation
What is the major difference between the right and left cardiac cycles?
Left has higher peak pressure generated
What is preload?
Filling pressure at the end of diastole; loading of ventricle
What is afterload?
Pressure in the wall of the ventricle during ejection; pressure the ventricles must push against
What determines preload?
Atrial pressure at the end of diastole
What is a healthy ejection fraction?
Greater than 55%
What is the formula for ejection fraction?
Stoke volume/LV end diastolic volume
What does the Fick equation determine?
Organ use of oxygen (arterial conc,-venous conc.)
