Cardiac Cycle Flashcards
What are the 5 stages of the cardiac cycle?
1) Phases in pumping action of the heart
2) Opening and closing of valves
3) Changes in aortic, ventricular and atrial pressure, contraction and relaxation of heart muscle
4) Changes in ventricular volume
5) Heart sounds
What occurs in phase one of the cardiac cycle?
Mid to late ventricular diastole, ventricular filling, AV valves open and SL valves shut, finally atrial contraction
What occurs in phase two? (Ventricular systole)
Isovolumetric contraction this is where ventricles contract but pressure isn’t high enough to open the SL valves, therefore ventricular volume remains constant
What happens in phase three? (Ventricular systole)
Ventricular ejection, this is where SL valves open and AV valves shut
What happens in phase 4? (Early ventricular diastole)
Isovolumetric relaxation - ventricles relax, still too much pressure to allow AV valves to open and not enough pressure to maintain SL valves open. Therefore all valves are shut and there is no change in blood volume in ventricles.
In diastole is the aortic valve open or closed?
Closed
In aortic pressure what type of pressure is the minimum?
Diastolic
In aortic pressure what type of pressure is the maximum?
Systolic
What is the dicrotic notch?
Caused by shutting of aortic valve
What is the name of the average aortic pressure occurring in cardiac cycle?
Mean arterial pressure
What is the calculation for pulse pressure?
Systolic pressure - diastolic pressure
What does a high pulse pressure indicate?
Hardening of the arteries (reduced elasticity)
What is the calculation for mean arterial pressure?
Diastolic pressure + (pulse pressure/3)
Why is there not an average between diastolic and systolic pressure?
Aortic pressure closer to minimum (diastolic) for more time than maximum
What is the calculation for stroke volume?
End diastolic volume - end systolic volume
What is ejection fraction?
Ratio of volume ejected in one beat to volume immediately prior to ejection
What is the calculation for ejection fraction?
Stroke volume / end diastolic volume
What is the first sound of the cardiac cycle?
Occurs at the start of systole when AV valves close
What is the second sound of the cardiac cycle?
Start of diastole when semi lunar valves close
What is the cause of heart sounds?
Turbulent rush of blood through valves as they narrow and close
What is coronary artery disease caused by?
Accumulation of atherosclerotic plaque in coronary arteries, which restrict blood flow to the myocardium
What are the three phases of coronary artery disease?
- Endothelial dysfunction, more adhesion molecules, chemokine, tissue factors, less endothelium-dependent vasodilation
- Fatty streaks
more VSMC migration, proliferation, platelet derived mediators - Complicated lesions more macrophages, T-cells, necrotic lipid core, tissue factor, more plaque vulnerability and thrombogenicity
What is the name of the process that detects coronary artery disease?
Angiography
What are the two routine procedures used to treat CAD?
Angioplasty and bypass graft
