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Module 10 > Ultrasound of Heart SDL > Flashcards

Ultrasound of Heart SDL Flashcards

1
Q

how is the patient prepared for ultrasound

A

clip over apical beat and apply water & gel

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2
Q

what is the patient position

A

right then left lateral recumbency

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3
Q

why is the echocradiogram done in lateral recumbency

A
  1. the lateral recumbency, the lower lung partially collapses under the weight of the heart and mediastinum –> this process in the lower lung is known as hydrostatic congestion and the upper most lung hyperinflates to compensate
  2. also the heart is fixed at the base but free at the apex so in lateral recumbency the cardiac apex falls towards the lower thoracic wall and pushes the lung out of the way

bigger area which is free from air filled lung

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4
Q

what transducers are best suited for imaging the heart

A

phased array due to small areas of contact with skin

produces a fan shaped image and allows visualization of a large structure like the heart through the small intercostal spaces

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5
Q

what is the B or brightness mode

and why is it used

A

produces the familiar real time grey scale images that represents a thin slice through the patient and vary the direction of the beam

  1. allows orientation of heart
  2. ensure that entire heart is examined systematically and no features missed
  3. performance of a repeatable exam and performance of standard measurements which are necessary for the comparison of findings to published results
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6
Q

what is the standard right parasternal view obtained

A

with the beam orientated at right angles to the long axis of the heart and roughly parallel with the intercostal space

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7
Q

what will the chambers of the heart appear

A

anechoic or black because blood = fluid

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8
Q

what does the muscular wall of the heart appear as

A

echogenic

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9
Q

what does the pericardium appear as

A

hyperechoic line around the outside of the heart and produces an acoustic shadow with reverberation artefact due to the air filled lung immediately beyond it

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10
Q

what are 3 standard right parasternal short axis views through the hear

A
  1. left ventricle
  2. mitral valve (fish mouth)
  3. heart base (aorta, pulmonic trunk and left atrium)
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11
Q

identify the structures on long axis view (standard right parasternal view)

A
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12
Q

how is the right parasternal long axis of the left ventricle obtained

A

first obtain the short axis view through the left ventricle and then rotate the transducer through 90° so the beam is orientated parallel to the long axis of the heart and roughly at right angles with intercostal space

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13
Q

what can be seen on the right parasternal long axis view of the left ventricle

A

can see the left atrium, mitral valve and left ventricles

the interventricular septum is located between the left and right ventrcles

the right side of the heart is still in the near field of image so it may not be weel imaged due to distortion of beam

it is possible to see the right atrium, tricuspid valve and right ventricle

the pericardium appears as hyperechoic line adhered to outside of heart

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14
Q

what are the right parasternal long axis views

A
  1. left ventricle and left atrium –> chordae tendinae
  2. left ventricle and aorta
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15
Q

what is the hyperchoic strands that can be seen running through the mtiral valve in this view

A

papillary muscles which represent the chordae tendinae that serve to tether the mitral valve leaflets and are therefore normal structures

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16
Q

what are the LPS views

A
  1. 4 chamber: left atrium, left ventricle, mitral valve, right atrium, right ventricle and tricuspid valve
  2. 5 chamber: directing the beam so the aortic outflow tract also appears

in these views blood is flowing either directly up the screen through the mitral valve and tricuspid valves or down the screen through the aortic valve –> useful for doppler

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17
Q

summarize all the views in RPS short axis, RPS long axis, LPS views

A
  1. RPS short axis: left ventricle, mitral valve, heart base (aorta, pulmonic trunk and left atrium)
  2. RPS long axis: left ventricle & left atrium, left ventricle & aorta
  3. LPS: 4 chamber, 5 chamber
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18
Q

what is M-mode/time-motion mode used for

A

performed using standard B-mode images

a cursor line is positioned through B-mode image –> displayed against time as a chart across the screen that is updated

can be used with ECG to identify the stage of the cardiac cycle

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19
Q

how is cardiac wall thickness measured

A

a standard right parasternal short axis through the left ventricle at the level of the papillary muscles immediately below the level of the chordae tendinae

M-mode cursor is positioned so it bisects a symmetrical line through the left ventricle between the papillary muscles

measured at end diastole (onset of QRS complex) and at systole (T wave)

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20
Q

what can the B-mode RPS long axis through LV and LA be used for

A

to assess

LV lumen diameter

end diastole - MV open/max area

end systole 4

21
Q

what can also be used to measure LV thickness

A

M-mode LV function

RPS short axis through LV

22
Q

what is the shortening fraction and what info does it provide (what would reduction, increase mean)

A

the measurements of LV lumen diameter and interventricular septum are fed into equation on machine to produce a shortening fraction

provides info regarding the function or contractility of the left ventricular wall

reduction suggests reduced cardiac function and an increase means compensatory hypercontractility (incompetent mitral valve)

23
Q

what is the normal shortening fraction range in dogs and cats

A

dogs: 25-45%
cats: 30-55%

24
Q

how is ejection fraction determined and why is it used

A

by calculating the ejection fraction

using B mode RPS long axis through the left ventricle and left atrium:

  • image is stopped at both end diastole and end systole (using ECG or by determining the point which internal diameter of LV is at max and min)
  • cursor drawn round the internal surface of the LV –> calculate the internal area at end diastole and end systole
  • comparison of values gives ejection fraction
25
Q

what is the normal value of ejection fraction

A

>50%

26
Q

how is E-point to septal separation (EPSS) calculated and what is normal value

A

M-mode measurement

using standard B mode RPS short axis view at level of mitral valve (fishmouth view)

-cursor is placed through the mitral valve and the resulting M mode trace demonstrates the movement of the 2 valve leaflets with time as they make M and W shape –> distance between valve and IVS

normal <7mm

27
Q

what does EPSS value indicate

A

early indicator of left ventricular volume overload and dilation

28
Q

how is left atrial size measured

A

standard B mode RPS short axis image through base of heart

freeze image with aortic valve visible (mercedes benze appearance)

cursor used to directly compare the diameter of left atrium and the aorta at systole

29
Q

what are the normal ratio values of left atrium and the aorta measurement

A

dogs: 1:1-1.4
cats: 1:1.2-1.7

30
Q

what are the M-mode measurements

A
  1. wall thickness (LV and interventricular septum)
  2. shortening fraction (LV function)
  3. ejection fraction (LV function)
  4. E-point septal separation (EPSS) (LV dilation)
31
Q

what are the B-mode measurements

A
  1. left atrial enlargement (LA:aorta)
32
Q

what are the 3 ways doppler assess blood flow

A
  1. direction
  2. velocity (beam parallel with direction movement = most accurate)
  3. uniformity (laminar vs. turbulent)
33
Q

what is colourflow doppler and what mode is it

A

standard B-mode images used to guide doppler “gate” placement:

  • LPS 4/5 chamber views (aorta, MV, TV)
  • RPS SA heart base view (pulmonic trunk)
34
Q

what do the colours of the doppler mean

A

BART

blue = away from transducer (aortic/pulmonic outflow)

red = towards transducer (mitral/tricuspid inflow)

35
Q

how is the pulmonic outlfow tract best visualized using doppler

A

using standard RPS short axis view through the base of the heart where normal pulmonic outlfow is also downt the screen, away from the transducer (blue)

36
Q

how are valvular incompetences identified with doppler

A

opposite colour of flow in the wrong direction between the normal pulses or inflow or outflow depending on the valve

turbulent flow produces a mulitcoloured appearance (mosaic)

37
Q

what does colour flow doppler not allow measure of

A

velocty

38
Q

how is spectral doppler used

A

colourflow used to guide placement of spectral doppler cursor box over areas of normal inflow/outflow and over any areas of abnormal flow

activation of pulsed wave produces a trace of blood flow through the box against time

39
Q

what do mitral/tricuspid flow appear like on spectral doppler pulsed wave

A

in standard B mode LPS 4 chamber views

  • mitral and tricuspid inflow is up the screen towards the transducer –> normal inflow is peaks above the baseline
    normal: two peaks during every diastole

first peak (E): or early peak due to passive filling of ventricles from atria and then flow reduces as the valves begins to close

the second peak (A): contraction of atria before the valves close completely at the onset of systole

40
Q

how are aortic/pulmonic flows assessed using spectral doppler

A

aortic valve is assessed using standard B-mode LPS 5 chamber view

pulmonic valve: standard B-mode RPS short axis view through the base of the heart

41
Q

what does normal aortic/pulmonic flow appear on spectral doppler

A

normal outflow: during systole is a single peak below the baseline with a white outline and black centre –> normal laminar flow (velocity can be measured)

42
Q

what does regurgitant aortic/pulmonic outlfow appear as on spectral doppler

A

can be seen during diastole between peaks of normal outflow and is in opposite direction and above baseline (ECG used to identify this)

usually turbulent so incompetence produces an “envelope” on the trace that is filled in with white rather than a black centre and white outline in the normal laminar outflow

43
Q

what is the Bernoulli equation and what info does it give

A

velocity = height/depth of peak

p1-p2 = 4V^2

the velocity of regurgitant flow across a valve can be measured

can be used to measure the pressure differences across the valve (can give info if heart is functioning in presence of incompetent valve)

44
Q

what is continuous wave doppler used for

A

measure flow in areas that has exceeded the capacity of pulsed wave

45
Q

when is continuous wave doppler used

A

in cases with pulmonic and aortic stenosis where the restricted area is present causes a high velocity blood flow past it

ex. this trace shows aortic outflow being measured below the baseline at a speed of more than 4 m/s (normal is 1.2 m/s) –> also regurgitant flow present above the baseline between the peaks of outlfow and both sets of flow have an envelope that is filled in

46
Q

what is B (brightness) mode RPS and LPS standard views used for (4)

A
  1. identify physical changes
  2. subjectivetly assess the function of heart (although have to be quite marked before this is possible on B-mode images alone)
  3. objective measurement of cardiac structures such as determining the size of atrium
  4. guide M-mode/doppler cursor placement
47
Q

what does the M (motion) mode allow assessment of

A

objective measurements of cardiac chamber size and left ventricular function

48
Q

what are the doppler modes and what are they used to measure

A
  1. colourflow: info regarding the direction and uniformity of flow but does not allow us to objectively measure flow velocity (large screen areas of flow within the heart and guide placement of spectral doppler gate)
  2. pulsed wave spectral doppler: objectively measure blood flow within the heart and will identify the regurgitant and turbulent flow (limit to max velocity it can measure)
  3. continuous wave: used when max velocity is exceeded in pulsed

Module 10 (27 decks)

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