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Year 3 MOD > Small Animal Cardiology and Respiratory Medicine: ECG/Interactive > Flashcards

Small Animal Cardiology and Respiratory Medicine: ECG/Interactive Flashcards

(58 cards)

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1
Q

What is the definition of an ECG?

A

A recording of the changed in electrical potential difference (voltage) in the heart occuring during depolarisation and repolarisation of the myocardium plotted against time

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2
Q

What part of the heart is the pacemaker?

A

Sinoatrial node

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3
Q

Describe how the PQSRT complex is formed?

A
  • SAN spontaneously depolarises and spreads across right and left atrium forming the P wave
  • As this reaches the AVN conduction is slowed giving the P-R interval
  • The wave reaches the bundle of His which branches to purkinje fibres and the ventricle depolarises forming the QRS complex
  • The ventricle then repolarises slowly giving the T wave
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4
Q

How should the patient be connected to the ECG machine?

A

Gently restrained in right lateral recumbancy

Crocodile clip electrodes attached to loose skin just above elbows and stifles

Red- right fore
Yellow- Left fore
Green- Left hind
Black- right hind- earth lead

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5
Q

Which ECG lead is themost important lead to examine and why?

A

Lead II

This shows the largest complexes in dogs and cats

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6
Q

Where do each of the leads record changes in electrical potential difference between?

A

Lead I- right fore and left fore

Lead II- right fore and left hind- parrallels the position of the heart

Lead III- the left fore and left hind

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7
Q

How can HR be worked out on an ECG?

A

Obtained over a 6 second strip- no of QRS complexes x 10

For dysrythmias it is better to determine mean HR over longer period of time

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8
Q

After HR is worked out what should be checked?

A

P: QRS ratio should be 1:1

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9
Q

When first looking at an ECG checking the predominant rhythm what should be checked?

A

Inspect regularity and morphology for any dysrythmia

P waves should be identified if possible- regularity and uniformity

QRS- normal and narrow

QRS always followed by T waves- can be negatie, positive or biphasic in dogs, cats usually positive

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10
Q

How do you measure and multiply an ECG?

A

Standard lead II measurments are taken at 50mm/s and a sensitivity of 1mv=1cm

1mm box is 0.1mV x 0.02s

Measure P wave amplitude (height) (mV)
Measure P wave duration (length)(seconds)
Measure P-R interval

Measure height of R wave
Measure duration of QRS complex
Measure QT interval

T wave is noted to be positive, negative or biphasic
ST segment should be at a similar level of the baseline P-QRS

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11
Q

What are some common ECG abnormalities from measurment?

A

Prolonged P wave- left atrial enlargment

Tall P wave- right atrial enlargment

Tall R wave- left ventricular enlargment

Prolonged QRS complex- ventricular enlargment

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12
Q

What is the name for normal heart rythm?

A

Sinus rhythm

P wave preceding every QRS complex and a QRS following a P wave

It can vary with respiration- sinus arrythmia- normal in dogs indicating normal, high resting vagal tone

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13
Q

How is a sinus arrest presented on an ECG?

What casues it?

A

The ECG shows a gap with no electrical activity for a period exceeding normal R intervals

Often a manifestation of high vagal tone- may be normal in brachiocephalics

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14
Q
A
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15
Q

What is an AV block and how many different types are there?

A

When the AV node either slows or blocks conduction of the atrial depolarisation into the ventricles

3 types- first degree, second degree, third degree

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16
Q

How is a first degree AV block presented on an ECG?

A

P:QRS ratio remains 1:1 but the P-R interval is longer than normal.

May be due to high vagal tone or effect of certain drugs/disease

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17
Q

How is a second degree AV shosn on an ECG?

A

Some P waves not followed by a QRS complexes

May be normal and physiological (horses) but may reflect disease of the AVN

QRS should look normal

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18
Q

What are the two types of second degree AV block and how are they different?

A

Wenckeback phenomenon- Mobitz type 1 AV block
Single non-conducted P wave- every now and then

Mobitz type 2 AV block
Every other P wave is non conducted or higher every 2/3

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19
Q

What is a 3rd degree AV block on an ECG?

A

P waves bear no relationship with the QRS complex

P waves occur at their own normal rate and QRS cmoplexes arise due to much slower automaticity of the purkinje system

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20
Q

What is atrial fibrillation?

A

When the atria are sufficiently large or stretched normal cell conduction representing P wave lost

Leads to many irregular depolarisations in the atria which randomly hit the AV node

QRS complexes and T waves look normal but rate is fast and the interval between them is highly variable- no P waves

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21
Q

What causes a supraventricular premature complex/supraventricular tachycardia?

A

If an ectopic focus in the atria or at the atrioventricular junction depolarises the atria prematurely a premature complex with the appearance of a normal QRS complex is produced

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22
Q

What is the name for a run of supraventricular premature complexes?

A

Paroxysmal supraventricular tachycardia

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23
Q

What causes a ventricular premature complex/ventricular tachycardia and how does this affect the complex?

A

An ectopic focus may also arise in the ventricular myocardium- it doesn’t follow the normal His-purkinje so is spread cell to cell- slow process so the complex is wide and bizarre

The T wave is in the opposite direction of the QRS complex

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24
Q

What causes paroxysmal ventricular tachycardia and sustained ventricular tachycardia?

Study These Flashcards
A

A run or ventricular premautre complexes

If sustained it causes sustained ventricular tachycardia

25
What are the hallmarks of ventricular premature complexes?
Ventricular ectopic complexes- Wide and bizzare And slur into oppositely directed T waves
26
How would you know a ventricular ectopic origniated in the right/left ventricle?
Ventricular ectopics which are positive in leads I and II with negative T waves are probably originating in the right ventricle Negatvie leads in I and II with positive T waves probably originate in the left ventricle
27
Describe a ventricular fibrillation ECG
Complete loss of coordinates ventricular depolarisation/repolarisation- chaotic
28
What 'other' factors influence the ECG?
Autonomic nervous system- vagal tone, sympathetic drive Electrolyte distrubances- electrical activity depends on conc of electrolyes Cardiac disease- chamber enlargment Other diseases- gastric stetch, spleen tumours
29
What may hyperkalaemia show on an ECG?
Sinoventricular rythm but no discernable P waves Normal QRS- tall spikey T waves
30
What type of ultrasound transducers are required to get between ribs and lung lobes?
Sector transducers- inverted fan shaped image
31
What is the difference between long axis and short axis views in echocardiography?
Long axis- base to apex Short axis- cross sectional views
32
What does the right pasternal long axis view show? What is the right pasternal long axis view used for?
Shows all 4 chambers of the heart and thickness of the walls Used for: * Assess LV shape- normal, elliptical, rounded * Subjectively assess contractility * Right should be no more then one third of left heart dimensions * LV walls should be one-quarter to one-thirds chamber diameter * Mitral valve assessed- regurgitation? * Can calculate EDV (start of QRS) and ESV (end of T wave/ smallest LV dimension) * Atrial septum is assessed
33
What is seen with the RPS long axis 5 chamber view? What can be assessed with this view?
All chambers and the aorta viewed Used to assess abnormalities of the aortic valves Colour flow can be used to look for turbulence in this region- stenosis Colour flow can also be used to check septum for a ventricular septal defect
34
What is seen with the right parasternal short axis view- papillary muscle level? What is this view used for?
The RV and LV Used to position the M-mode cursor- at chordae tendinae
35
What is the M-mode cursor?
The M-mode cursor plots one dimension and is therefore a motion-time graph Movement of the structures is displayed relative to the ECG That wavy shit
36
Name each of the views A-E
A- RPS short axis below papillary muscle B- Between pappillary muscle level- mushroom view C- Left ventricular M-mode- chordae tendinae level D- RPS short axis- mitral valve level (fishmouth view of mitral valve) E- RPS short axis view at level of aortic valves
37
What is seen with M-mode cardiography?
Body wall Right ventricle- only a bit Intraventricular septum- IVS Left ventricular lumen- LV Left ventricular wall- LVpw
38
What is measured with M-mode echocardiography?
End diastolic measurements- start of QRS- broadest levt ventricular lumen Systolic measurments- smallest left ventricle lumen Can also measure: Intraventricular septum diastole/systole LV posterior wall diastole/systole Measurements compared to breed specific reference values
39
How is fractional shortening calculated and what is normal? When is fractional shortening not reliable?
LV internal diameter diastole - systole / diastole x100% Normal is above 25% Not reliable if- significanct mitral regurgitation, wall motion abnormalities, right sided heart disease with pressure overload
40
What is fishmouth view/mitral valve used to measure?
AMV- anterior mitral valve leaflet and PMV- posterior mitral valve leaflet Irregular thickening of leaflets with DVD Can occasionally see mitral stenosis Mitral E point to septal seperation (top of E to septum distance)- increases with LV dilations, rounding of LV or poor stoke volume
41
What is the M-shape created from fishmouth M-mode?
The AMV inscribes the M-shape with two peaks The **E** peak- **E**arly passive diastolic filling- after T wave The **A** Peak- **A**trial contraction- after P wave Posterior leaflet should do opposite- W shape
42
How is the LV volumes and ejection fractions calculated?
In RPS long axis view Work out EDV and ESV and % Use simpsons method of discs Normal is \>50%
43
What is the index of sphericity of the LV?
Attempting to quantify subjective assessment of rounding of LV LV length- diastole / LV 'width' (M-mode) anything above 1:7 normal
44
What is the difference between concentric and eccentric hypertyrophy?
Concentric- thickening and reduced lumen Eccentric- over all enlargment Eccentric- big ego
45
What disease is seen in cats and causes them to have thickened walls of the heart? What needs to be ruled out?
Hypertrophic cardiomyopathy in cats Things that cause pressure overload- Aortic stenosis and systemic hypertension
46
What does the short axis view at the level of aortic valves show? What can be measures and compared at this view?
Short axis of the left atrium and aortic leaflets seen (mercedes) Measure aortic root and LA in diastole for 2D measurment Normal LA:Ao is \<1.5
47
What is doppler echocardiography? What are the three different types?
Doppler effect is noted when sound waves are transmitted and reflected off a moving target- RBCs The difference between ultrasound frequencies transmitted and received is related to the velocity of the moving RBCs Spectral Colour flow Tissue- myocardial motion
48
What is required to make spectral doppler echocardiography accurate?
Must be parrallel to flow of blood Otherwise velocities significantly underestimated
49
How does blood moving towards the transducer and away show differently?
Blood moving towards the transducer is displayed above the baseline Blood moving away from the transducer is displayed below the baseline
50
How is laminar/turbulent flow indicated on pulsed wave doppler?
A clean envelope as blood accelerates and decellerates Turbulent flow is indicated by spectral dispersion and loss of clean envelopes
51
What is the difference between Continuous wave doppler and Pulse wave doppler?
PW- spatially specific, just sample RBC velocity within the sample volume. But limit to depth you can sample and peak velocity you can record CW- samples all along the cursor line- peak velocities displayed but not spatially specific Can record depth and high peak velocities
52
What is colour flow doppler?
Colour applied to how above or below baseline the velocity is BART map- blue away, red towards transducer
53
What is the Nyquist limit?
There is only a certain red level and velocity than can be reached which is the nyquist limit It is a circle so becomes blue again and shows aliasing
54
How does turbulence show in colour flow doppler?
Colour variance- green/yellow
55
What view is used for aortic stenosis?
Sub-costal view Optimal alignment with aortic outflow
56
What is the modified bernouilli equation used for?
Calculates the pressure gradient difference- beterrn LV and Aorta PG = 4V^2 0-40 mmHg- mild 40-80 mmHg- moderate \>80mmHg- severe Normal aortic velocity -1.7m/s
57
What are the normal cardiac pressures in aorta, LA, pulmonary artery, LV, RV, RA?
Aorta- 120/80 normal sytemic pressure Left atrium- 6mmHg LV- 120/0 mmHg RV- 25/0 mmHg RA- 4 mmHg
58
What causes caval syndrome and does it cause and how is it treated?
Dirofilariasis worms in the RA Causes pulmonary hypotension and thromboembolism and pressure overload on RV- right sided CHF Need to extract worms via jugular vein

Year 3 MOD (42 decks)

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