The cardiac cycle describes each heart beat, incorporating relaxation and contraction. Phase one describes diastole and you can see above that atrial & ventricular pressure are both low but atrial pressure is higher than ventricular pressure - this sets up the through through of blood when the atria end up contracting. You can also see how the ventricular pressure ends up below the atrial pressure after isovolumetric relaxation.The ventricular volume rises slightly during diastole and then to its peak at the end of atrial systole. Aortic pressure is always high but falls during diastole, then peaks during ventricular systole.There is a dicrotic notch after the first fall after peak aortic pressure - this is when the aortic valve closes and a backup of pressure (aorta > LV) leads to a second, smaller peak. During rapid inflow, the ventricular volume, but not pressure increases. #Pathophys #Cardiology #CardiacCycle #Stages #Systole #Diastole #HeardSounds #Pressures #Phonogram #Electrocardiogram #Graphs
