cardiac cycle Flashcards
what does the cardiac cycle show? (3)
the events that occur as the heart contracts and relaxes; the relationship between electrical activity and heart contraction; changes in blood volume related to pressure in the cardiac chamber
draw the cardiac cycle graph
check one note
what are the 7 stages in the cardiac cycle
systole - atrial systole; isovolumetric contraction; rapid ejection; reduced ejection
diastole - isovolumetric relaxation; rapid ventricular filling; diastasis
what occurs in atrial systole (LV pressure, heart sounds, ventricular volume, RA pressure, ECG)
LV pressure - increasing pressure as ventricular volume is increasing;
heart sounds - s4 (only herd if ventricle is hypertrophic and stiff)
ventricular volume - increases slightly
RA pressure - increases
ECG - P wave seen due to SAN depolarising, Q wave beginning
what occurs in isovolumetric (LV pressure, heart sounds, ventricular volume, RA pressure, ECG)
LV pressure - rises rapidly, but still not > aortic pressure and so aortic valve remains closed
heart sounds - S1 (mitral valve closing)
ventricular volume - no change
RA pressure - rises (c) bc contraction causes the atria to also bulge
ECG - QRS complex
what occurs in rapid ejection (aortic pressure, LV pressure, heart sounds, ventricular volume, RA pressure, ECG)
aortic pressure - increases to pmax
LV pressure - increases, surpassing aortic pressure and causing the aortic valve to open
heart sounds - end of S1
ventricular volume - decreases rapidly, rate slows (at n^-x) as blood leaves slower
RA pressure - decreases back to neutral at first but then begins to rise as blood from the veins accumulates
ECG - ST segment, baseline, no electrical activity
what occurs in isovolumetric relaxation (aortic pressure, LV pressure, heart sounds, ventricular volume, RA pressure, ECG)
aortic pressure - increases after the dicrotic notch due to backflow of blood as aortia > ventrical pressure (so blood pulled to lower pressure)
LV pressure - decreases rapidly as inertial energy drives blood flow out, aortic valve closes
heart sounds - S2, aortic valve closes (this occurs before pulmonic)
ventricular volume - decreasing more slowly
RA pressure - increases as blood is accumulating from veins
ECG - baseline
what occurs in reduced ejection (aortic pressure, LV pressure, heart sounds, ventricular volume, RA pressure, ECG)
aortic pressure - decreases from p max
LV pressure - decreases, reaching a pressure below that of the aorta causing the aortic valve to close (at end)
heart sounds - n/a
RA pressure - increases as blood accumulates from veins
ECG - T wave seen as depolarisation occurs
what occurs in rapid ventricular filling (aortic pressure, LV pressure, heart sounds, ventricular volume, RA pressure, ECG)
aortic pressure - decreases
LV pressure - still decreasing but far more slowly, mitral valves open
heart sounds - S3 heard in children
ventricular volume - increases rapidly as mitral valves are open which allows blood to flow into the ventricles
RA pressure - decreases as blood is flowing to ventricles
ECG - baseline
what stage does most of ventricular filling occur
rapid ventricular filling (diastole)
what occurs in reduced ventricular filling (LV pressure, heart sounds, ventricular volume, RA pressure, ECG)
LV pressure - minimally increasing
Heart sounds - n/a
ventricular volume - increases
RA pressure - plateau
ECG - baseline
what sounds are the “gallop heart” sounds
S3 (rapid ventricular filling, in children or heart failure) or S4 (atrial systole, if ventricle is stiff)
what is S1
the closing of the mitral and tricuspid valves (mitral first, usually hard to distinguissh the two)
what is S2 and when does splitting occur
the closing of the aortic and pulmonary valves -semi lunar valves (aortic first); splitting of the sound may be heard on inspiration as this increase blood flow to the right side and thus the RA takes longer to pump out the increases volume, as fixes splitting may be heard if there is an atrial septal defect
when is an ejection systolic murmur heard
between S1 and S2
