1 CVS Flashcards
(159 cards)
1
Q
Rate of diffusion depends on 3 factors, these are:
A
- Area available for exchange
- Concentration gradient
- Diffusion resistance ie. nature of the molecule, the barrier, the path length
2
Q
The area available for exchange depends on…
A
capillary density
3
Q
Which tissues will have higher capillary density?
A
Metabolically actuve tissues
4
Q
How is the concentration gradient (necessary for diffusion) maintained?
A
By sufficient blood flow, bringing more of the substance to the capillary bed.
5
Q
The rate of the blood flow determines the …. …. driving O2 diffusion into the cells
A
Concentration gradient.
So tissues that are more metabolically active need a higher blood flow
6
Q
the higher the rate of metabolism, the … the demand for O2 and nutrients.
A
greater
7
Q
Increases in metabolism must be met by increase in … …
A
blood flow
8
Q
the rate of blood flow is known as the…
A
perfusion rate
9
Q
The brain needs what sort of blood flow? description and value
A
The brain needs HIGH, CONSTANT flow.
approx. 0.5 ml/min.g
10
Q
The heart muscle needs what sort of blood flow? description and value
A
The heart need high flow which increase during exercise.
Approx. 0.9-3.6 ml/min.g
11
Q
Kidney need what sort of blood flow? description and value
A
Kidneys need HIGH, CONSTANT flow.
Approx. 3.5 ml/min.g
12
Q
What is the approx. cardiac output for a 70kg male? And what if he’s exercising?
A
5 L/min
Can go up to 25 L/min!
13
Q
What are the layers of the pericardium and heart wall?
A
Fibrous layer - non distensable Parietal layer - outer serous cavity Pericarial cavity Visceral layer - Inner serous layer, = epicardium Myocardium Endocardium
14
Q
What is cardiac tamponnade? What is the treatment?
A
It is compression of the heart due to fluid accumulation in the pericardial cavity. The heart will no longer be able to fill correctly.
May need to do a pericardiocentesis, ie. remove fluid to relieve compression (+ test liquid)
15
Q
What is heart compression due to fluid build-up in percardial cavity called?
A
cardiac tamponnade (ttt= pericardiocentesis)
16
Q
Where is the pericardial transverse sinus located? Why is it clinically relevant?
A
Behind the ascending aorta and pulmonary trunk. (but in front of/not as far as the superior vena cava)
It is a useful landmark if we need to clamp the aorta and install extracorporeal circulation, here in particular heart-lung bypass (also called CPB cardiopulmonary bypass)
17
Q
Where is the oblique sinus located? Why is it clinically relevant?
A
On the posterior surface of the heart, just below where the 4 pulmonary veins meet.
It is clinically relevant as may need to place swab there to avoid blood accumulation suring surgery.
18
Q
What is a heart lung bypass and where are it’s cannulae placed?
A
A heart-lung circulation is a sort of extracorporeal circulation.
The aortic cannula is place just above the clamped aorta (clamp is placed just above the pericardial transverse sinus) and the venous cannula is placed in the inferior vena cava and superior vena cava.
19
Q
Where do the left and right coronary arteries originate from?
A
They originate at the very base of the ascending aorta.
- Right aortic sinus
- Left aortic sinus
20
Q
Where does the Right coronary artery run?
A
Along the right atrium, between right atrium and right ventricle.
21
Q
Where does the left coronary artery run, and which are its major branches?
A
It runs behind the left auricle, and its major branches are
- left circumflexe artery
- left anterior descending (or interventricular) artery
22
Q
What is another name for the Left Anterior Descending artery?
A
Interventricular artery
23
Q
Where does the left anterior descending artery run?
A
between the right and left ventricles
24
Q
What are the left and right aortic sinuses?
A
They are the origins of the right and left coronary arteries.
25
Which coronary artery is most likely to get blocked in myocardial infarction?
The left anterior descending coronary, also called anterior interventricular artery, or even the "widow maker"
26
Awhat is the "widow-maker" and why is it bare that name?
It is a coronary artery that arises from the left coronary artery.
Also called: left anterior descending or interventricular.
It is called the widow maker as it is the mist common coronary to be affected in MIs
27
Where does the right marginal artery arise from and where does in run?
The right marginal artery arises from the rught coronary artery and it runs along the inferior edge of the right ventricle toward the apex of the heart
28
What is the coronary sinus?
It is where all the cardiac veins drain to, before joining the right atrium
29
From which vessels does the right atrium receive blood?
2 vena cava (sup/inf) and th coronary sinus
30
What happens if a major coronary artery gets blocked?
MI
31
4 major heart valve names and location?
1. Mitral - LA-LV
2. Tricuspide - RA-RV
3. Aortic - LV-aorta
4. Pulmonary - RV-pulmonary trunk
32
What is responsible for S1 sound?
Closing of mitral and tricuspide valves
33
What is responsible for S2 sound?
closing of aortic and pulmonary valves
34
In which circumstances do you hear an S3 sound?
1. Children - non-pathological
2. Adults - pathological, associated with heart failure.
S3 would occur during rapid filling phase of the cardiac cycle, this is phase 6.
Normally filling should be silent in adults.
35
What are capacitance vessels and what function do they serve?
They are venous vessels that enabke the system to vary the amount of blood pumped around the body. They vessels will accomodate the volume if needed.
36
What are resistance vessels and which function do they serve?
They restrict blood flow to drive supply to active tissues.
They will adapt the % of cardiac output going to various tissues according to the activity.
It is arterioles that are major resistance vessels!
37
Systemic circulation is a ... pressure circuit
HIGH
38
Pulmonary circulation is a ... pressure circuit
LOW
39
Output of left and right sides over time must be ...
equal
40
What is the typical pressure in right atrium?
0-4 mmHg
41
What is the typical pressure in the left atrium?
8-10 mmHg
42
What is the typical pressure in the right ventricle?
25 systole/4 diastole
43
What is the typical pressure in the left ventricle?
120 systole/ 10 diastole
44
What are the typical pressures in the aorta?
120 systole / 80 diastole
45
What are the typical pressures in the pulmonary artery?
25 systole / 10 diastole
46
What is systole?
Contraction and ejection of blood from ventricles
47
What is Diastole?
relaxation and filling of the ventricles
48
Which of the ventricles is more muscular?
Left, higher pressures to deal with!
49
What is the average stroke volume for a 70kg male at rest?
70 ml/beat
50
What is stroke volume?
It is the volume that the ventricles eject at each heart contraction
51
How does cardiac muscle contraction relate to other muscle tyoes?
They are LONG last for the duraitin of a single contraction 280ms. (makes sense as needs to be transmitted to all myocytes)
52
Which valves have papillary muscles and cordae tendinae?
Mitral and tricuspide to avoid prolapse (during systole) under pressure into the atria.
53
Give a few characteristics of cardiac muscle cells
1. They are a specialised form of muscle
2. They are individual cells, not a true syncytium, but they are interconnected by gap junctions
3. They have sarcomeres, t-tubules
4. Their ends branch into two
54
Hoe long does a cardiac action potential last and how does this compare to other muscle types?
~280ms
| This is LONG compared to other muscle types
55
What does the opening/closing of valves depend on?
Opening/c'osing of valves depends solely on differential blood pressure on each side.
This means that they function mechanically.
56
What is the runction of papillary and cordae tendinae
They prevent valve prolaspe into atria when they close.
57
What sort of cells make up the sinoatrial node?
The are NOT nervous cells but specialised myocytes.
58
Why is the atrioventricular node important?
It is important because it delays transmission of the AP to the ventricules. we don't want ventricle contraction at the same time as the atria, as we need ventricles to fill during atrial contraction.
59
How can we describe the "shape" of the heart contraction?
Like an 8.
It starts at the apex, then goes upwards and twists.
Also, AP conduction goes from endocardium to epicardium; ie. in to out
60
How many phases are there in the cardiac cycle?
7
61
What are the phases of the cardiac cycle in the correct order?
1. Atrial contraction
2. Isovolumetric contraction
3. Rapid ejection
4. Reduced ejection
5. Isovolumetric relaxation
6. Rapid filling
7. Reduced filling
62
Which of the cardiac cycle phases are systolic?
2. Isovolumetric contraction
3. Rapid ejection
4. Reduced ejection
63
Which of the cardiac cycle phases are part of diastole?
5. Isovolumetric relaxation
6. Rapid V filling
7. Reduced V filling
8. Atrial contraction
64
What is the total duration of a cardiac cycle at 67 beats/min?
0.9 seconds
65
Which of diastole and systole can change in duration to adapt to heart rate?
Diastole can shorten.
| systole will always be te same length, (ie. at 67 betas/min, systole is 0.55 s)
66
For which side of te heart is the wiggers diagram typically plotted?
only the left!
67
If we were to draw a wiggers diagram for the right side of the heart, what differences would we see compared to the left?
It would be very similar to the typical Wiggers diagram for the left, only at lower pressures.
68
1 cardiac cycle is how many systoles and diastoles?
1 systole
| 1 diastole
69
What are the axis of a Wiggers diagram?
1. Upper part: Pressure/time [s]
| 2. Lower graph: Volume/time [s]
70
What different curves does a wiggers diagram comprise?
1. Aortic pressure
2. Left atrial pressure
3. Left ventricular pressure
4. Left ventricular volume
5. Electrocardiogram
6. Phonocardiogram
71
What is the phase 1 of the vardiac cycle?
Atrial contraction
72
What is the phase 2 of the cardiac cycle?
isovolumetric contraction
73
What is the phase 3 of the cardiac cycle?
Rapid ejection
74
What is phase 4 of the cardiac cycle?
Reduced ejection
75
What is phase 5 of the cardiac cycle?
Isovolumetric relaxation
76
What is phase 6 of the cardiac cycle?
Rapid filling
77
What is phase 7 of the cardiac cycle?
Reduced filling
78
What happens during phase 1 of the cardiac cycle?
This phase is atrial contraction.
- A wave: rise in LA pressure due to atrial contraction
- Ventricular volume rises, but only a little. Atrial contraction only accounts for the final 10% of ventricular filling. This value rises with age and exercise.
- This phase starts with P wave. P wave is an ECG wave that indicates onset of atrial depolarisation.
79
What is the "A wave" and on which curve does one see it?
The A wave is a left atrial pressure wave.
| It is due to atrial contraction causing an increase in atrial pressure.
80
What drives ventricular filling?
80% on ventricular filling is due to residual blood from previous contraction and passive falling from atria into ventricle.
10-20% only of filling is due to atrial contraction
81
What is the EDV.
End Diastolic Volume.
- this is the maximal volume the ventricule will hold
- typically 120ml
82
What is the typical value for EDV?
120ml
83
Which valves are open/closed during phase 1 of the cardiac cycle?
Mitral/tricuspide valves are open
| Aortic/pulmonary valves are closed
84
What happens during isovolumetric contraction?
Starts with mitral valve closing as ventricular pressure exceeds atrial pressure. So both valves gating the ventricle are closed, and the ventricle contracts.
- Closure of the mitral valve causes C wave in atrial pressure curve
- Ventricular pressure rises rapidly as ventricle contracts
- EDV doesn't vary as ventricular volume is fixed by closed valves
- QRS complex in ECG curve signifies onset of ventricular depolarisation
- S1 due to closure of mitral and tricuspide valves
85
What is "QRS"?
QRS are 3 segments of the ventricular contraction fluctuation on the ECG curve.
86
What is the C wave and on which curve of a a Wiggers diagram is it observed?
C wave corresponds to a small atrial pressure increase following mitral/tricuspide valve closure. It is consequently observed on the atrial pressure curve.
87
During which phase of the cardiac cycle is S1 heard and what does it result from?
S1 is heard during isovolumetric contraction phase (as it starts with mitral valve closure which is responsible for S1 sound)
88
During phase 2 of the cardiac cycle, which valves are open/closed
All closed!
89
What occurs during phase 3 of the cardiac cycle?
- aortic valve opens
- rapid decrease in ventricular volume
- atrial pressure decreases! Why? because as the ventricles contract, the atrial base is pulled down, freeing up more space, thus decreasing the pressure inside the atrium = X descent
90
What is the X descent, and in whihc phase does it occur?
X descent is a decrease in atrial pressure during rapid ejection (ph. 3) due to the atrial base being pulled down when ventricle contracts thus widening the atrium.
91
What occurs during phase 4 of the cardiac cycle?
- rate of ejection begins to fall as ventricle is repolarised, ecause of the decline in tension
- atrial pressure gradually rises due to continued venous return from the lungs = V wave of atrial pressure curve
- ECG curve: T-wave, it depicts the repolarisation of ventricle
92
What occurs during phase 5 of the cardiac cycle?
- pressure in ventricle has fallen sufficiently for aortic/ pulmonary valve to close
- pressure falls rapidly
- volume stays identical as valves are all shut
- ventricular volume is fixed on ESV
- dicrotic notch: on the aortic pressure curveis caused by valve closure
- S2! from closure of aortic/pulmonary valves
93
What is the dicrotic notch and on which curve of Wiggers diagram is it observed?
It it a short rapid wave in aortic pressure due to valve closure.
94
What is end systolic volume and when is it observed?
- end systolic volume ESV is the lowest ventricular volume observed during the cardiac cycle, ie after ejection
- it is observed on the ventricular volume curve
95
What is stroke volume, and how csn it be expressed using volumes?
Stroke volume is the volume of blood ejected at each ventricular contraction.
It is calculated: EDV - ESV
96
What is the typical stoke volume?
~80 mmHg
97
What occurs during phase 6 of the cardiac cycle?
Phase 6 = Rapid filling
- Starts with mitral valve opening
- Fall in atrial pressure called the "Y-descent" (this only appear as a small drop !)
- ventricular volume rises importantly
- ventricular pressure stays low and constant
- MAY hear S3 sound. If child, then normal. If adult, then sign of heart failure, as ventricle is still containing a lot of blood and the filling form atria is abnormal.
98
What occurs during phase 7 of the cardiac cycle?
Phase 7 = reduced filling
- rate of filling slows down = diastasis, so ventricular volume stabilises as it reaches its inherent relaxed volume
- at rest the ventricules are 90% full by the end of phase 7.
99
What 2 sorts of abnormal valve function can occur?
1. Stenosis
| 2. Regurgitation
100
What is valvular stenosis and its general consequences?
Stenosis is when the valve doesn't open properly causing obstruction to blood flow.
101
What is valvular regurgitation and its general consequence?
Regurgitation is when a valve does not shut properly resulting in back-leakage of blood when valve should actually be closed.
102
Which valves are the most commonly affected by valvulopathies?
Mitral and aortic
103
What are 3 common causes for aortic valve stenosis?
1. Degenerative - ie. old age calcification/fibrosis
2. Congenital - the valve is bicuspide instead of tricuspide
3. Chronic rhumatic inflammation causes commissural fusion
104
What are the 3 consequences of aortic valve stenosis?
1. Increased LV pressure, so heart hypertrophy as has to make a greater effort on ejection
2. Left sided heart failure causing syncope and angina
3. The blood is now pushed through a smaller opening and this can damage the RBCs = shear stress, with the consequence of "Microangiopathic haemolytic anaemia"
105
What are 2 main causes of aortic valve regurgitation?
1. Aortic root dilation - so leaflets are further apart and can no longer obstruct passage
2. Valvular damage by endocarditis such as rhumatic fever
106
What is rheumatic fever and how does it affect the heart?
Rheumatic fever is an inflammatory disease that can affect heart, joints, skin and brain.
The disease typically develops two to four weeks after a streptococcal throat infection.
The damaged valves cause REGURGITATION which may result in heart failure, atrial fibrillation and infection of the valves.Regurgitation can occur at all valves, but most commonly aortic or mitral.
107
What happens in aortic valve regurgitation?
- Blood flows back into LV during diastole
- Increase in stroke volume
- Systolic pressure increases
- Diastolic pressure decreases
- Bouding pulse (head bobbing, Quinke's sign)
- LV hypertrophy
108
What is a bounding pulse?
It occurs when PULSE PRESSURE IS INCREASED.
A bounding pulse occurs when the aortic valve is incompetent leading to regurgitation. The stroke volume is higher, and the heart beats stronger to eject the increased volume. Sometimes, head of patient moves with each beat = head bobbing
109
What sound does one hear in patient with aortic valve regurgitation?
early decrescendo diastolic murmur after S2
110
What sound does one hear whne patient has aortic valve stenosis?
Crescendo-decrescendo murmur
111
What are 4 common causes of mitral valve regurgitation?
- myxomatous degeneration of chordae tendinae and papillary muscles, that are then weakened and lead to valvular prolapse.
- damage to papillary muscle after heart attack
- left sided heart failure leads to LV dilation which can stretch valve
- Rheumatic fever can lead to leaflet fibrosis which disrupt seal formation
112
What happens during mitral valve regurgitation?
- Some blood flows back into LA increasing PRELOAD
- preload is increased as there is now more blood entering the ventricle in subsequent cycles.
- can lause LV hypertrophy
113
What is a Quinke sign?
This is when the nail bed flushes and then goes pale with each heart beat. It occurs in some cases of aortic valve regurgitation, as a consequences of increased stroke volume
114
What is the most common cause of mitral valve stenosis?
- 99.9% rheumatic fever!
115
What sound is heard in mitral valve regurgitation?
Holosystolic murmur
116
What are the consequences of mitral valve stenosis?
- it is harder for blood to flow LA => LV
- So LA pressure increases, causing...
1. Pulmonary oedema, dyspnea, pulmonary hypertension => RV hypertrophy
2. LA dilation
=> atrial fibrillation => thrombus formation
=> oesophagus compression => dysphagia
117
Which sort of valvulopathy can cause pulmonary oedema and RV hypertrophy?
Mitral valve stenosis
118
Which sort(s) of valvulopathies cause LV hypetrophy?
Aortic valve regurgitaiton
| Aortic valve stenosis
119
Which type of valvulopathy can cause anaemia?
Aortic valve stenosis
120
In which valvulopathy can one see Dysphagia due to the oesophagus being compressed?
Mitral valve stenosis
| Less blood can flow into LV, so build up in LA, causing LA dilation which can impinge on oesophagus.
121
What is plasma?
```
It is the fluid collected from un clotted blood.
Ie. one of 3 layers of centrifuged blood
- plasma
- buffy coat (white blood cells)
- RBCs
```
Blood plasma is a straw colored liquid component of blood that normally holds the blood cells in whole blood in suspension; this makes plasma the extracellular matrix of blood cells. It makes up about 55% of the body's total blood volume.[1] It is the intravascular fluid part of extracellular fluid (all body fluid outside of cells). It is mostly water (up to 95% by volume), and contains dissolved proteins (6–8%) (i.e.—serum albumins, globulins, and fibrinogen),[2] glucose, clotting factors, electrolytes (Na+, Ca2+, Mg2+, HCO3−, Cl−, etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation) and oxygen. Plasma also serves as the protein reserve of the human body. It plays a vital role in an intravascular osmotic effect that keeps electrolytes in balanced form and protects the body from infection and other blood disorders.
122
What is serum and why is it different to plasma?
Serum is the liquid phase collected from clotted whole blood.
So serum is plasma without clotting factors especially fibrinogen!
123
We say coronary arteries but ... veins
cardiac
124
What is by far the most common cause eased whole blood viscosity?
Multiple myeloma
125
What is CABG?
Coronary Artery Bypass Grafting
- type of surgery that improves blood flow to the heart.
- treatment for coronary heart disease
- CHD is a disease in which a waxy substance called plaque builds up inside the coronary arteries
- Over time the plaques can harden (and obstruct lumen) or rupture (blood clot at plaque surface obstructing lumen)
126
What is heparin?
Heparin is an anticoagulant
127
What us peripheral resistance?
It is the resistance opposed by arterioles
128
What can change in the blood for it to become viscous?
1. Plasma viscosity can increase leading to whole blood viscosity increase
2. RBC, platelet or white blood cell increase can lead to whole blood viscosity increase
129
What does sludging mean?
Intravascular slowing or clumping of RBCs
130
How does viscosity vary with temperature and how does this relate to the body peripheries?
Viscosity increases with the cold. And peripheries are colder, so viscosity of blood increases in body peripheries
131
Why does myeloma cause blood viscosity to increase?
Become there is a huge amount of protein in the blood.
| The proteins in question are serum immunoglobulins.
132
Is turbulent or laminar flow "normal"?
laminar
133
What is laminar flow?
It is the flow of blood in streamlines with each layer of blood remaining the same distance from the wall.
When laminar flow occurs, the VELOCITY of blood in the center of the vessel is greater than that towards the outer edge creating a parabolic profile.
134
What is turbulent flow?
- blood flowing in all directions in the vessel and continually mixing within the vessel
- when the rate of blood flow becomes too great (flow is NOT velocity)
- when blood passes by an obstruction in a vessel
- when blood makes a sharp turn
- when it passes over a rough surface (like atheroma)
- when there is increased resistance to blood flow
135
In which clinical situation is blood flow turbulent?
Anaemia! The heart rate is increased and so is cardiac output to compensate lack of oxygen being delivered to tissues.
The turbulent flow may lead to murmur!
136
What are the units of flow?
volume/time
137
What are the units of velocity?
distance/time
138
Do flow and velocity necessarily change together and in same direction?
No!
| Flow can decrease and velocity increase, it is the case in stenosis for example!
139
In which case does flow decrease and velocity increase?
stenosis
140
What can happen if there are 2 stenosis in series?
flow might stop completely!
- the first one slows it down
- second one stops it completely
=> this is the last thing we want in an artery, in the leg we call it physical ischemia
141
what is a "bruit" in the context of cardiac sounds?
It is a vibration that one can hear just after a stenosis.
| "sounds like a plane taking off"
142
What is a "thrill " in the context of cardiac auscultation?
A thrill is a vibration one can feel just after a stenosis
143
What is a murmur?
If it's a vibration across a heart valve (like a bruit, but valvular)
144
What is the dichrotic notch?
It is the point at which the aortic valve shuts, causing a ery slight pressure increase, and then dicrotic limb cintinues (ie. descendant part of curve)
+ the dicrotic notch defines the transition between systole and diastole.
145
How is pulse pressure defnied?
It is the difference between peak systolic pressure and the end diastolic pressure.
So when we measure BP with a sphygomanometer, pulse pressure is
systolic pressure - diastolic pressure
so most often, pulse pressure is 120mmHg - 80mmHg = 40mmHg
146
What is mean arterial pressure and how is it calculated?
Mean arterial pressure can be estimated as:
diastolic pressure + 1/3 of pulse pressure
Therefore, most often, mean arterial pressure is 80+13mmHg = 93
If mean arterial pressure falls below 70mmHg, then organ perfusion is impaired
It is ALSO the area under the curve when looking at a pressure/time diagram of teh descending aorta
147
Below which mean arterial pressure threshold is organ perfusion impaired?
70 mmHg
148
What is the pulse?
1. What we actually feel is a shock wave that arirves slightly before the blood itself
2. the strength or what is also called the volume of the pulse is determined primarily by 2 things:
a) The force with which the LV is able to eject blood .
b) Pulse pressure the greater the oulse pressure, the stronger the pulse. a strong pulse is often described as "bounding"
149
What can the causes of reduced pulse volume be? (3)
1. LV failure
2. Aortic valve stenosis
3. Hypovolemia (dehydration, bleeding)
such a pulse is often described as thready
150
In which context is pulse pressure widened?
bradycardia
151
Which non-pathological contexts can induce low peripheral resistance? (3)
1. Hot bath
2. Exercice
3. Pregnancy - because have little boiler inside you producing heat so need to vasodilate to get rid of the heat
152
How can low peripheral resistance induce a bounding pulse?
If peripheral resistance is low, then diastolic decline will be more quick, so blood will rush out into peripheral ciruclation, so diastolic pressure is lower, causing the bounding pulse.
153
Why do we see a bounding pulse in patients with aortic incompetence?
In aortic incompetence, the aortic valve cannot close properly. So during diastole, some blood will flow back into the LV.
But because this blood is no longer in the aorta during diastole, then aortic diastolic pressure is lowered.
But if systolic pressure is the same and diastolic pressure is lower, then pulse pressure is LARGER.
And bounding pusle occurs wirth a larger pulse pressure
154
What are the units of flow?
volume/time
155
what are the units of velocity?
Distance/time
156
What does stenosis do to proximal (ie. upstream) pressure?
increase
157
What does stenosis do to distal (ie. downstream) flow and velocity?
Distal flow decreases with stenosis
| Distal velocity increases with stenosis
158
How does a stenosis create an aneurism?
The pressure proximally to the stenosis rises, and this can create the enlargement of the artery that we call an aneurism.
159
Why can one not necessarily find a pulse when palpating an older person?
Part of the arterial tree calcifies with age, loses compliance and now cannot feel a pulse.
