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*CVS Jeny > S1) Haemodynamics > Flashcards

S1) Haemodynamics Flashcards

1
Q

What is haemodynamics?

A

Haemodynamics is the study of how pressure affects blood flow in blood vessels

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2
Q

Define infarction

A

Infarction is tissue death due to inadequate blood supply

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3
Q

Distinguish between the blood flow to different tissues of the body:

  • Brain
  • Kidneys
  • Heart
  • Skeletal muscle
  • Gut
A
  • Brain needs high, constant flow
  • Kidneys need high, constant flow
  • Heart muscle needs high flow which can vary
  • Blood flow to skeletal muscle increases during exercise
  • Blood flow to gut increases after a meal
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4
Q

What is perfusion rate?

A

Perfusion rate is the rate of blood flow (l.min-1)

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5
Q

Increases in metabolism are met by increases in blood flow.

Compare and contrast the perfusion rate at rest and during exercise

A
  • At rest - total blood flow is about 5 l.min-1
  • During exercise - total blood flow can rise to 25 l.min-1
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6
Q

State the factors that affect the rate of diffusion

A
  • Area available for exchange
  • Diffusion resistance
  • Concentration gradient
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7
Q

Describe what determines the area available for exchange in diffusion

A
  • Area available for exchange between capillaries and tissues depends on capillary density
  • A tissue which is more metabolically active will have more capillaries & a higher capillary density
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8
Q

Identify the 3 factors which affect diffusion resistance

A
  • Nature of the molecule
  • The barrier
  • Distance
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9
Q

Describe what determines the concentration gradient in diffusion

A

The perfusion rate determines the concentration gradient driving O2 diffusion into the cells

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10
Q

What is pericardial effusion?

A

Pericardial effusion is when excess fluid accumulates in the pericardial cavity, compressing the heart due to the inextensible fibrous pericardial layer

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11
Q

What is the danger associated with pericardial effusion?

A

Compression of the heart can lead to cardiac tamponade as the heart cannot fill during diastole

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12
Q

How can excess fluid be removed from the pericardial cavity?

A

Through a procedure called pericardiocentesis, excess fluid is removed for testing / to relieve compression

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13
Q

What is coronary circulation?

A

Coronary circulation is the circulation of blood in the blood vessels of the heart muscle (myocardium)

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14
Q

What are coronary arteries?

A

Coronary arteries are the vessels which deliver oxygen-rich blood to the myocardium

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15
Q

What are cardiac veins?

A

Cardiac veins are the vessels that remove the deoxygenated blood from the myocardium

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16
Q

Describe the general origins and location of the left and right coronary arteries and their branches

A
  • Origins: base of the aorta from openings (coronary ostia) located behind the aortic valve leaflets
  • Location: lie on the surface of the heart
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17
Q

State the specific origins of the left and right coronary arteries

A
  • Right coronary artery rises in the right aortic sinus
  • Left coronary artery rises in the left aortic sinus
18
Q

What is the problem associated with coronary arteries?

A

Coronary arteries are vital to supply well oxygenated blood to the myocardium however, they are prone to atheroma wherein a thrombus forms and can block the artery

19
Q

Which artery is commonly blocked in an AMI and which regions does it supply?

A
  • Left anterior descending artery (LAD)
  • Supplies the apex of the heart, the septum and the left ventricle and a bit of right ventricle
20
Q

Discuss the relationship between pathology in the aortic and mitral valves

A
  • The aortic and mitral valves are closely associated
  • Hence, if a disease affects one it will likely affect the other
21
Q

What is serum?

A

Serum is plasma minus the clotting factors

22
Q

What is the main clotting factor in the body?

A

The main clotting factor is fibrinogen

23
Q

What are the contents of buffy coat?

A

Buffy coat contains white blood cells and a few platelets

24
Q

Differentiate between the different types of fluid collected from blood

A
  • The fluid collected from unclotted blood = plasma
  • The fluid collected from clotted blood = serum
25
Q

Identify 4 factors which increase whole blood viscosity

A
  • Increase in plasma viscosity
  • Polycythaemia: increase in red blood cells
  • Leukaemia: increase in white blood cells
  • Thrombocythaemia: increase in platelets
26
Q

What is the effect of increases in whole blood viscosity?

A

Increased whole blood viscosity leads to sludging in the peripheries

27
Q

Identify the commonest cause for increases in plasma viscosity leading to increased whole blood viscosity

A

Multiple myeloma

28
Q

In terms of plasma viscosity, how can one attempt to measure inflammation?

A
  • Results from raised levels of acute phase plasma proteins e.g. fibrinogen, complement factors and CRP which increase in response to inflammation
  • Hence, minor changes in plasma viscosity can be used to ‘measure’ the inflammatory response
29
Q

Explain the difference between flow and velocity of blood

A
  • Velocity is the distance blood has moved per unit of time (cm/sec)
  • Flow is the volume of blood that is moving per unit of time (l/min)
30
Q

Explain the difference between laminar and turbulent flow

A
  • Laminar flow: blood usually flows in streamlines with each layer of blood remaining the same distance from the wall
  • Turbulent flow: blood flows in all directions in the vessel and continually mixing within the vessel
31
Q

Identify 5 situations wherein turbulent blood flow could happen

A
  • When the perfusion rate becomes too great
  • When the blood passes by an obstruction in a vessel
  • When the blood makes a sharp turn
  • When the blood passes over a rough surface
  • Where there’s increased resistance to blood flow
32
Q

What is peripheral resistance?

A

Peripheral resistance is the totality of the resistance being posed to the blood pumped from the heart

33
Q

What is the impact of low peripheral resistance?

A

Low peripheral resistance lowers diastolic pressure and therefore increases pulse pressure due to the vasolidation of arterioles e.g. hot bath, exercise, pregnancy

34
Q

What is the impact of high peripheral resistance?

A

High peripheral resistance raises diastolic pressure and therefore decreases pulse pressure due to the vasoconstriction of arterioles e.g. cold, thirsty

35
Q

What is a pulse?

A

A pulse is a rhythmical throbbing of the arteries as blood is propelled through them, typically as felt in the wrists or neck

36
Q

Differentiate between the terminology for weak and strong pulses

A
  • A weak pulse is often described as “thready”
  • A strong pulse is often described as “bounding”
37
Q

Which 2 factors determine the strength (volume) of a pulse?

A
  • The force with which the left ventricle is able to eject blood into the arterial system and thus develop a normal shock wave
  • The pulse pressure
38
Q

Identify conditions which lead to a stronger/weaker pulse

A
  • Weaker pulses can result from left ventricular failure, aortic valve stenosis, hypovolaemia (severe dehydration, bleeding)
  • Stronger pulses can result from bradycardia seen in conditions such as heart block
39
Q

Explain what Phase I and Phase 5 are when measuring blood pressure

A
  • Phase 1 – the point at which the first sound appears
  • Phase 5 – the point at which the sounds disappear
40
Q

What is pulse pressure?

A

Pulse pressure is peak systolic pressure – end diastolic pressure

120mm Hg – 80 mm Hg = 40mm Hg

41
Q

Describe the impact of pulse pressure on the volume of the pulse

A

The greater the pulse pressure the stronger the pulse

42
Q

Define mean arterial pressure

A

- Mean arterial pressure is estimated as diastolic pressure + 1/3 of the pulse pressure

  • Therefore, most commonly, mean arterial pressure is 80 mmHg + 13 mmHg = 93 mm Hg

*CVS Jeny (17 decks)

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