CVPR Week 2: Cardiac Cycle Flashcards
1
Q
Objectives
A
2
Q
The heart functions as?
A
3
Q
Anatomy of heart chambers
A
4
Q
Mitral valve resembles a?
A
Bishops miter
5
Q
Heart valves
4 listed
A
6
Q
Cardiac cycle key points
A
- Electrical events precede mechanical events
- Atria contract prior to ventricles
- Flow moves from high to low pressure (in general)
- All valves are unidirectional
7
Q
Diastolic filling
A
- left atrium across left ventricle across mitral valve
- small pressure gradient drives blood from aorta to ventricle
- ventricle is in a relaxed state
- Tricuspid and mitral valves are open
- Semilunar valves are closed
8
Q
Semilunar valves
A
pulmonary and aortic valves
9
Q
Diastolic filling valve status
A
- Tricuspid and mitral valves are open
- semilunar valves are closed (pulmonary and aortic)
10
Q
Atrial systole
A
- atria are contracting facilitating the ventricle filling
- immediately preceded by the P-wave of the ECG
- increasing pressure gradient in the atria driving to the ventricle
- This contributes to < 20% of total ventricular filling at rest
- Can increase to 40% with heavy exercise
11
Q
P-wave
A
P-wave results from atrial depolarization
12
Q
Ventricular systole
A
- the ventricles contract period of isovolumic contraction (short period of time when the ventricular pressure is still lower than aortic pressure so the aortic valve remains closed
- Mitral valve closes
- Aortic valve closes
- All valves closed
- The Same volume of blood as in the end of atrial systole = end diastolic volume
- corresponds to the QRS complex
13
Q
typical end diastolic volume
A
Textbook ~ 120 mL
14
Q
Isovolumic contraction description
A
- a short period of time when the ventricular pressure is still lower than the aorta
- all valves are closed
- the volume of blood is the same as it was at the very end of diastole (end-diastolic value)
15
Q
Isovolumic contraction occurs when?
A
During ventricular systole
16
Q
Isovolumic contraction AKA
A
Same volume contraction
17
Q
corresponds to the QRS complex
A
immediately precedes Ventricular systole
18
Q
corresponds to the P-wave
A
immediately precedes Atrial systole
19
Q
Ventricular systole - ventricular ejection
A
- As soon as ventricular pressure exceeds aortic pressure the aortic valve opens
- The stroke volume is the volume of blood that is ejected from the ventricle at this time
20
Q
The stroke volume
A
is the volume of blood that is ejected from the ventricle during ventricular ejection
End-diastolic volume (120 mL) - End-systolic volume (40 mL) = stroke volume (80 mL)
Typically 80 mL
21
Q
Ejection fraction
A
Stroke Volume (80 mL) /End Diastolic Volume (120 mL) = Ejection fraction (67%)
typically 67% at rest
- can be up around 90% in elite athletes with heavy exercise
- can be down around 20% with congestive heart failure
22
Q
Isovolumic relaxation
A
- follows the T-wave of ECG (reflects ventricular repolarization)
- no blood flow valves are closed because the left atrium has lower pressure and aortic pressure is higher than that of the left ventricle
- however, during this period, the left atrium is increasing in pressure due to blood returning from the pulmonary veins
23
Q
Diastolic filling resumes
A
as soon as ventricular pressure is less than atrial pressure the mitral valve opens and blood rushes in the ventricle
~ 80% of ventricular filling from this phase
24
Q
Complete cardiac cycle
A
Wigger’s Diagram
- Reduced ventricular filling
- Atrial systole
- ventricular isovolumic contraction
- ventricular ejection
- Isovolumic relaxation
- Diastolic filling resumes
25
Wigger's Diagram: Atrial Systole: Venous pressure waveform
venous pressure waveform: a wave: atrial contraction
the only thing is that the atria do contribute to ventricular filling which is not represented on this diagram
26
Wigger's Diagram: Atrial Systole: Heart sounds
S4: Atrial contraction (not normal, occurs with ventricular hypertrophy)
27
Wigger's Diagram: Isovolumic contraction: venous pressure waveform
c wave: displacement of AV valve during isovolumic contraction of the ventricle
period of constant volume
28
Wigger's Diagram: Isovolumic contraction: Heart sounds
S1: Closure of A-V valves (Lub heart sound)
29
Wigger's Diagram: Ventricular ejection: features
* Aortic valve opens
* broken down into rapid ejection period and reduced ejection period
* big fall in ventricular volume
* In the reduced ejection period, the ventricles are beginning to relax
* associated with T-Wave of ECG
30
As soon as ventricular pressure exceeds atrial pressure
the mitral valve closes
31
When atrial pressure is greater than ventricular pressure
the mitral valve opens
32
Wigger's Diagram: Isovolumic contraction: diagram features
* ventricular volume remains constant
* ventricular pressure rapidly increasing
* short period of time with constant volume as ventricular pressure is still less than aortic pressure
33
When aortic pressure exceeds ventricular pressure
the aortic valve is closed
34
When aortic pressure is less than ventricular pressure
the aortic valve opens
35
Wigger's Diagram: Isovolumic contraction: venous pressure waveform
C wave displacement of AV valve during isovolumic contraction of the ventricle
36
T wave is during this period and represents
* systole
* reduced ventricular ejection
* represent repolarization of ventricles
37
in reduced ventricular ejection ventricular pressure
* actually falls a little below aortic pressure but the aortic valve remains open due to the inertia created by the ventricular contraction and blood continues to be ejected for a short period of time despite the reversal of the pressure gradient
* Slight reversal but still have blood flow
38
Ventricular repolarization is the start of?
Relaxation
39
Wigger's Diagram: Isovolumic relaxation: features
* when ventricular pressure falls below aortic pressure the aortic valve closes but the mitral valve is also closed (ventricular volume is constant during this time because ventricular pressure is still greater than atrial pressure)
* Dicrotic notch- results from elastic recoil of the aorta and aortic valve closure
* S2 heart sound
* atrial pressure is increasing during this time since the mitral valve is closed
40
Dicrotic notch
results from elastic recoil of the aorta and aortic valve closure
Aorta essentially function s as a secondary pump even when the ventricles are relaxing driving blood (hydraulic filtering phenomenon)
41
Wigger's Diagram: Isovolumic relaxation: Heart sounds
S2 closure of semilunar valves (dub heart sound)
42
Wigger's Diagram: Rapid ventricular filling: Heart sound
* Not normal, caused by rapid ventricular filling by high pressures in the left ventricle
* S3 heart sound: Rapid ventricular filling (caused by high filling pressures and sudden deceleration of blood flow into the LV, e.g. with CHF, leaky mitral valve)
* Caused by poorly compliant heart vessels
43
Abnormal heart sounds
S3 and S4 heart sounds caused by poorly compliant ventricles
44
Question
45
Question
46
Question
47
Question
48
Pressure in the right side of the heart
49
Blood volume in the left and right side of heart
very important that right and left cardiac outputs are equal
if not blood can pool in places like the lungs (pulmonary edema) happens to patients with heart failure
if pulmonary fails can have build up in lower extremities
50
Chronic pulmonary hypertension leads to?
51
Coronary flow during the cardiac cycle
52
Summary
53
Associated with T-Wave of ECG
Ventricular ejection period and represents ventricular repolarization
54
Associated with P-Wave of ECG
Atrial systole and represents atrial depolarization
55
Associated with QRS complex of ECG
Ventricular contration (preceedes isovolumetric contraction period)
