Cardiac Cycle Flashcards
Name the two atrioventricular valves and state which side of the heart they are on and number of cusps.
Tricuspid 3 Right
Mitral 2 Left
List the 7 phases of the cardiac cycle
Atrial Contraction Isovolumetric Contraction Rapid Ejection Reduced Ejection Isovolumteric Relaxation Rapid filling Reduced Filling
In a raised or slowed heart rate what changes time in systole, diastole or both?
Diastole
How much of the cardiac cycle systole?
1/3- 0.35s
Which vessels are resistance vessels?
Arterioles
Are veins resistance or capacitance vessels?
Capacitance
Which operates under higher pressure systemic or pulmonary circulation?
Systemic
What is diastole?
Relaxation and filling time for ventricles
What happens to blood in systole?
Ejected from contracting ventricles
Are cardiac action potentials long or short?
Long - 280ms
What is the outflow valve of the right vertical called?
Pulmonary valve
The aortic valve is the ….. valve of the left ……
outflow
ventricle
What causes the opening and closing of valves?
Differential blood pressure on each side.
Closing prevents back flow
Opening allows through flow.
Paillary muscles in the ventricles are connected to the mitral and tricuspid valves by what structure? Why do we need this structure?
Chordae-tendinae
Prevents inversion of valves in systole.
Where are the pace maker cells in a normal functioning heart?
SAN
What is the delay time of an action potential at the AV node?
120ms
Ventricular depolarisation flows in which direction within the myocardium?
Endocardium to epicardium.
What is the direction of ventricular contraction?
Contract from apex up- squeezing blood through aortic and pulmonary valves.
Which 3 stages of the cardiac cycle are in systole?
Isovolumetric contraction
Rapid ejection
Reduced ejection
Phase 1 of the cardiac cycle is atrial contraction - outline events and Wigger diagram features.
A wave - atrial depolarisation
P wave on ECG
Atria contract and ventricular EDV is reached (atria pump in the last 10%)
What phase of the cardiac cycle is started by S1?
What happens in this phase?
Phase 2: Isovolumetric contraction
S1 is the mitral and tricuspid valves shutting (Ventricular pressure now higher than atria)
QRS- ventricular depolarisation
Rapid rise in pressure but no volume change as aortic valve is shut.
C wave denotes a slight atrial pressure increase as the valve shuts
What is S2?
Closure of the pulmonary and aortic valves in isovolumetric relaxation (phase 5)
What happens in rapid ejection?
Phase 3 of the cardiac cycle is rapid ejection and starts with the aortic valve opening.
X descent on atrial pressure as the ventricluar contraction pulls the atrial base down.
Rapid decrease in volume with a rising pressure in the ventricle.
Aortic pressure increases.
While the ventricles contract what happens in the atria?
Atria fill from venous input
What is the V wave on the atrial pressure line?
In phase 4: reduced ejection atrail pressure gradually rises .
What ECG feature is present in reduced ejection?
T wave - ventricular depolarisation allows the ejection rate to fall.
What phase of the cardiac cycle is end systolic volume reached in?
Phase 5 with the closing of ventricular out flow valves. The volume in the ventricles is normally roughly 50ml. The valves shut because with depolarisation and relaxation ventricular pressure falls to lower than the arteries they have ejected into.
What phase of the cardiac cycle is end systolic volume reached in?
Describe other events in this phase.
Phase 5 with the closing of ventricular out flow valves. The volume in the ventricles is normally roughly 50ml. The valves shut because with depolarisation and relaxation ventricular pressure falls to lower than the arteries they have ejected into. After closure the outlet artery pressure increases slightly (dicrotic knotch), while ventricular pressure rapidly falls.
The mitral valve opens causing a Y descent in the atrial pressure in which cardiac phase?
Phase 6: Rapid filling.
The ventricle pressure is now lower than the aorta so the value opens and the blood fills the ventricles - pressure is stable in the ventricles but volume increases
The mitral valve opens causing a Y descent in the atrial pressure in which cardiac phase?
Phase 6: Rapid filling.
The ventricle pressure is now lower than the aorta so the value opens and the blood fills the ventricles - pressure is stable in the ventricles but volume increases.
Note filling can give an S3 heart sound, but generally silent
Outline events of Phase 7 of the cardiac cycle.
Reduced filling or diastase is when the ventricles get near there inherent relaxed volume and more filling is because of venous pressure.
What is valvular stenosis?
Valve fails to open enough
Is regurgitation a problem when the valve should be open or shut?
The valve fails to shut and so leaks when it should be shut.
What valve problem gives a crescendo-decrescendo murmur between S1 and S2?
Aortic stenosis
List 3 causes of aortic stenosis
Rheumatic fever
Congenital (bicuspid valave)
Degenerative age related fibrosis and calcification
Name 4 side effects of aortic stenosis
Left ventricular hypertrophy
Left sided heart failure - Syncope or Angina
Haemolytic aneamia
What 2 things can cause aortic regurgitation?
What murmur does it give?
Valve damage
Aortic root dilation
Early decrescendo diastolic murmur
List potential side effects of aortic regurgitation.
Increase SV which Increase sys pressure
Decrease dias pressure (blood leaks back)
Bounding pulse with Quinke’s sign and or head bobbing
LVH
Myxomatous degeneration can lead to what murmur?
Holosystolic murmur from mitral regurgitation
Myxomatous degeneration can lead to what murmur?
List other causes
Holosystolic murmur from mitral regurgitation
Heart attack damaged papillary muscle
Left side heart failure -LV stretched and dilated
Rheumatic fever - firbtoic leafelts
What murmur increases pre-load?
Mitral regurgitation- blood leaks back into LA so means more blood enters the ventricle when it contracts. Increased risk of LVH.
What valve defect gibes a snap and a diastolic rumble?
Mitral Stenosis
Outline complications of mitral stenosis
Increased LA pressure.
Blood backs up to lungs so pulmonary hypertension with dyspnea and pulmonary oedema. The RV hypertophies to cope.
LA dilates - AF and thrombi are a risk
The LA can compress the oesophagus and give dysphagia
