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Cardiorespiratory Block > W1: Heart, murmurs, imaging > Flashcards

W1: Heart, murmurs, imaging Flashcards

1
Q

what are the functions of the CV system?

A
  • Transport of nutrients, oxygen, waste products around the body
  • Transfer of heat (generally core to skin)
  • Buffers body pH
  • Transport of hormones (e.g. adrenaline from adrenals)
  • Assists in response to infection
  • Assists in formation of urine-filtration and circulation
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2
Q

Describe flow of blood in heart

A

IVs and SVC to R Atrium to R ventricle to pulmonary trunk (pulmonary arteries), pulmonary veins to L Atrium to L ventricle to Aorta

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3
Q

Describe the Heart valves

A

Atrioventricular Valves:

  • Tricuspid Valve
  • Bicuspid (Mitral) Valve

The atrioventricular (AV) valves prevent the backflow of blood from the ventricles to the atria when the ventricles are contracting. The chordae tendineae and papillary muscles play important roles in the normal function of the AV valves.

When the ventricles are relaxed: the chordae tendineae are loose, and the AV valves offer no resistance as blood flows from the atria into the ventricles.

When the ventricles contract: blood moving back toward the atria swings the cusps together, closing the valves. At the same time, the contraction of the papillary muscles tenses the chordae tendineae, stopping the cusps before they swing into the atria.

Semilunar Valves:

  • Pulmonary valve
  • Aortic valve

Do not have chordae tendineae since they do not need to be pulled downwards. When the semilunar valves close, the three symmetrical cusps support one another like the legs of a tripod.

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4
Q

Describe the layers of the heart

A 
Fibrous pericardium 
Parietal layer
Pericardial cavity with pericardial fluid in it
visceral layer (Epicardium)
-  mesothelium 
- thick layer of connective tissue

Myocardium (thickest layer)

  • cardiac myocytes
  • connective tissue
  • abundant capillaries

Endocardium

  • Endothelium (smooth to help blood flow)
  • Thin connective tissue
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5
Q

Define the cardiac cycle and describe its events

A

Cardiac cycle: The cardiac events that occur from the beginning of one heartbeat to the beginning of the next.

Cardiac Cycle:
• Ventricular Diastole (ventricular filling): large amounts of blood accumulate in the atria because of the closed AV valves. The atria contracts, increasing atrial pressure. AV valves open when atrial pressure > ventricular pressure. Blood flows from atria into ventricles. This is a period of rapid filling of the ventricles.
During the last moments of diastole, the atria contract and give an additional thrust to the inflow of blood into the ventricles.

  • Ventricular Systole (part 1 – Isovolumetric contraction): The ventricular pressure increases abruptly, causing the AV valves to close. The ventricles begin to contract in this closed chamber (all valves are still closed).
  • Ventricular Systole (Part 2 – Ejection): When ventricular pressure > aortic/pulmonary pressure: Semi lunar valves open. Blood is ejected at high pressure from the ventricles to the arteries.

• Ventricular Diastole (Isovolumetric relaxation): Ventricles relax, and ventricular pressure drops. Blood flows back against the cusps of the semilunar valves and forces them to close.
Blood starts to fill the relaxed atria. The AV valves remain closed, allowing ventricular pressure to drop. There is no filling of the ventricles

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6
Q

What is the equation for Cardiac output

A

SV x HR

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7
Q

What is end diastolic volume

A

End-Diastolic Volume (EDV): The amount of blood in each ventricle at the end of ventricular diastole (the start of ventricular systole).

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8
Q

What is end systolic volume

A

End-Systolic Volume (ESV): The amount of blood remaining in each ventricle at the end of ventricular systole (the start of ventricular diastole).

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9
Q

What do the normal heart sounds lubb and dubb produced by?

A

S1 “Lubb” - The first heart sound is produced by the closing of the AV valves.

S2 “Dubb” - The second heard sound is produced by the closing of the semilunar valves.

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10
Q

What is the function of intercalated discs in cardiomyocytes

A

Intercalated discs allow synchronised contraction of the cardiac myocytes.

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11
Q

Describe the transmission of nerve impulse through cardiac muscle

A

SA node –> internal pathways –> AV node –> Bundle of His –> Bundle branches (L and R) –> Purkinje fibres

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12
Q

Why is there a delay in the impulse spreading form he SA node to the AV node?

A

This small delay is important because it allows the atria to contract before the ventricles do.

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13
Q

Describe the action potential in (non nodal) cardiac muscle cells

A

Phase 0: rapid depolarisation due to influx of Na ions into cell.
(Na channels open as threshold is reached.) (Makes the inside more positive)

Phase 1: partial repolarisation
Na channels are inactivated. K ions move outwards through specialised K channels making the inside of the cell more negative.

Phase 2: plateau
Results from inward Ca2+ current counterbalanced by outward K+ currents.

Phase 3: Repolarisation
Ca currents become inactivated and the outwards K ions predominate.

Phase 4: resting potential (-80mV)

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14
Q

Define stenosis

A

Narrowing of a valve which reduces the blood flow through it

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15
Q

Define regurgitation

A

leaking of a valve which causes backflow of blood int he reverse direction

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16
Q

what is the refractory period ?

A

The period in which the membrane will not respond to a second stimulus for some time after an action potential

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17
Q

IS the apex of the heart the top or the bottom?

A

bottom (left ventricle)

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18
Q

Define a heart murmur

A

Unusual heart sound due to turbulent blood flow. e.g. a whooshing or swishing sound

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19
Q

where do you listen in for murmurs?

A

Aortic area
2nd intercostal space right sternal edge

Pulmonary area
2nd intercostal space left sternal edge

Tricuspid area
4th intercostal space left sternal edge

Mitral area
Cardiac apex (usually 5th intercostal space in the left midclavicular line)
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20
Q

Causes of heart murmurs and effects

A

Aortic stenosis
Mitral regurgitation

ASMR = heard during systole (I think these two are hypertrophy of left ventricle)

Aortic regurgitation
Mitral Stenosis

ARMS = heard during diastole (I think these two are dilation and hypertrophy)

Patent Ductus Arteriosus
Atrial Septal defects

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21
Q

Describe the coronary artery blood flow

A

Right Coronary artery:
Posterior descending inter-ventricular artery & Marginal artery

Left Coronary Artery:
Anterior descending inter-ventricular artery & left circumflex artery

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22
Q

What are causes of aortic stenosis?

A
  • Rheumatic Fever
  • Age-related Calcification (more common in the elderly)
  • Congenital bicuspid aortic valve - 2 of the cusps are fused and not formed properly at birth.
23
Q

What is the septum which separates the ventricles made up of?

A

Has small upper membranous part with the rest made of muscle

24
Q

When does the majority of the blood flow through he myocardium occur?

A

During diastole

25
Q

What is the coronary sinus

A

Coronary sinus is a wide venous channel that runs form left to right in the posterior part of the coronary groove.

26
Q

what vein drain intro the coronary sinus

A

Great, small, middle cardiac veins, oblique vein of the left atrium and the posterior ventricular vein

27
Q

what is the difference between nodal and non-nodal action potentials

A

SA Nodal: slow response, relies on CALCIUM, shorter action potential. No phase 1 or phase 2.

Non-nodal: faster, relies on SODIUM influx

28
Q

what’s the difference between skeletal and cardiac action potentials?

A

cardiac action potentials last for much longer (200-400 msec) than skeletal muscle (2-5 msec)

In cardiac pacemaker (SA nodal) cells, calcium ions are involved in the initial depolarisation phase.

in nerve and muscle cells, deportation is trigged by sodium channels opening

29
Q

Are murmurs always indicating of something dangerous?

A

no. May also be innocent. eg. occur in young people due to high flow through normal blood vessels. Or in adults at times of increased cardiac output e..g pregnancy

30
Q

List some of the imaging techniques used

A

X Ray
Echocardiogram
Coronary angiography
MRI

31
Q

Describe how echocardiogram works

A

Gel is applied to the chest area. Transducer/probe is placed on the chest and releases high frequency ultrasound waves. Some of these waves are absorbed and some of them are reflected back and the transducer picks them up as echoes. these are transmitted as electrical impulses and the echocardiography machine converts them into ultrasound images.

32
Q

What are the standard views of echocardiogram?

A

Short axis: cross section view of heart (Top view: Right and Left atria/ventricle – depending on where it’s sliced)

Long axis (LEFT ventricle and atrium)

Apical 4 chamber view

33
Q

Lists types of echocardiography

A

contrast
stress
doppler ultrasound
transoesophageal

34
Q

What does the echo Doppler measure ?

A

Assesses blood flow through the heart and blood vessels (their speed, direction etc)

35
Q

What is Echocardiography used to assess?

A

Valve assessment
pericardial assessment
structure and function of the heart
Inducible ischaemia (stress)

36
Q

Advantages of Echocardiography

A

No radiation
Readily available
Cheap
Portable

37
Q

Disadvantages of echocardiography

A
  • Requires good acoustic window – if too much tissue between then cannot see the heart valve.
  • User dependant (requires a lot of practice to perform)
38
Q

Describe exercise and nuclear stress testing

A
  • Exercise stress testing (assess ECG as patient exercises. During exercise, patient may get exertional chest pain = angina etc. if there is less blood flow to heart)
  • Nuclear stress testing – uses radioactive dye and an imaging machine to create pictures showing the blood flow to your heart. The test measures blood flow while you are at rest and are exerting yourself, showing areas with poor blood flow or damage in your heart.
39
Q

What is Nuclear perfusion imaging used to assess?

A

Assesses ischemia

40
Q

Advantages of Nuclear perfusion imaging

A

Availability

41
Q

Disadvantages of Nuclear perfusion imaging

A
  • Radiation

- No structural assessment – purely functional test

42
Q

describe coronary angiography

A

Special X ray test which uses contrast dye to check for coronary artery blockage. involves passing a tube into an artery until it reaches the heart. It is poked through a blood clot in the coronary arteries to allow normal blood flow.

43
Q

What is percutaneous coronary intervention?

A

Percutaneous coronary intervention: When tube/wire isn’t enough – pass a tightly wrapped balloon with a stent which goes in and then inflate the artery. This stretches the balloon and leaves stent in place. Blood flows through arteries.

44
Q

what is coronary angiography used for?

A

Ischemia
Valve assessment
ventricular pressures

45
Q

Advantages of coronary angiography?

A
  • Gold standard
  • Option for intervention during same procedure
  • Availability
46
Q

Disadvantages of coronary angiography?

A

Radiation

Risks – these are LOW (bleeding, death, MI, contrast reaction)

47
Q

What would the MRI be used to assess?

A

Structure and function (esp. left ventricle)
Perfusion/stress
assess great vessels
Tissue characterisation - conditions
e.g. previous infarction, hypertrophy, dilation etc.

48
Q

Advantages of MRI

A

No radiation
Gold standard left ventricular assessment
Reproducible

49
Q

Disadvantages of MRI

A
  • Pacemakers (becoming less of an issue)
  • Availability
  • Claustrophobia
  • Cost
50
Q

What type of endothelium is found in endocardium?

A

Simple squamous

51
Q

What are specialised cardiomyocytes?

A

Purkinje fibres

52
Q

why are purkinje fibres paler than cardiac myocytes?

A

They have fewer myofibrils

53
Q

Describe the action potential in SA nodal cells

A

Phase 4: gradual depolarisation due to leakage of Calcium into cell. Permeability to K is reduced so less outwards movement of K. Spontaneous depolarisation occurs when threshold is reached. This triggers an action potential.

Phase 0: depolarisation due to inward movement of calcium ions (slow)

Phase 3: Repolarisation due to outwards K movement

Cardiorespiratory Block (14 decks)

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