7 Phases Of Cardiac Cycle Flashcards
Preceded by QRS complex in the ECG
c wave of atrial pressure is seen
Ventricular pressure > Atrial pressure (AV valves will close [1st heart sound (S1) is heard]
Ventricular pressure
ISOVOLUMIC CONTRACTION
Atrial filling begins
Ventricular pressure > Aortic pressure (semilunar valves open, blood wil flow from Lav to aorta)
Key findings: Ventricular pressure (rapidly increase), Ventricular volume (decreases)
RAPID VENTRICULAR EJECTION
T wave occurs in the ECG
Aortic pressure also decreases because of runoff of blood from large arteries to smaller arteries
Key findings: Ventricular Pressure (decreases), Ventricular Volume (decreases)
REDUCED VENTRICULAR EJECTION
Incisura of aortic pressure is seen
v wave of atrial pressure seen
Ventricular Pressure Atrial Pressure (AV valves are still closed, no blood flow from atria to ventricles)
Key findings: Ventricular Pressure (decreases), Ventricular Volume (remains the same)
ISOVOLUMIC RELAXATION
Ventricular
RAPID VENTRICULAR FILLING
Longest phase of the cardiac cycle (dependent on heart rate)
Reduced increase in ventricular volume
Occurs during the middle 1/3 of diastole
REDUCED VENTRICULAR FILLING (DIASTASIS)
Occurs during the distal thrid of diastole
Peeceded by P wave in the ECG
NOT essential for ventricular filling
A wave of atrial pressure is seen
4th heart sound may be heard due to atria contracting against stiff ventricles (in LV hypertrohy)
Key findings: atrial pressure, ventricular pressure, ventricular volume (slightly increase)
ATRIAL CONTRACTION
Phases of Cardiac Cycle
Atrial contraction
ISOVOLUMIC contraction
Rapid ventricular ejection
Slow/reduced ventricular ejection
ISOVOLUMIC relaxation
Rapid ventricular filling
Slow/reduced ventricular filling
Cardiac events that occur in a single heartbeat
Cardiac cycle
