interpretation of ECG Flashcards

1
Q

what are 5 things to consider when looking at an ECG recording

A
  1. is the ECG of good quality such that you can use it to make a diagnosis (artifact?)
  2. what is the rate and rhythm
  3. are the QRS-t complexes normal(ish) or wide and bizarre
  4. is ther chamber enlargement or hypertrophy
  5. electircal axis
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2
Q

what type of artefact is this?

A

electromagentic interference caused by interferences of other electrical devices.
- remove or turn off electrical devices in the environment

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3
Q

what kind of artefact is this

A

wandering baseline –> loose electrode or pood skin preparation or patient moving

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4
Q

what is rate

A

how often the le impulses go through the heart

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5
Q

what is rhythm

A

the pattern of the electrical impulses travel across the heart

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6
Q

what artefacts are present? calculate the heart rat. is the rhytm regular or irregular

A

artefact: wandering baseline

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7
Q

calculate the rate. is the rhythm regular or irregular

A

rate: 1500 x13 = 115 bpm
rhythm = regular

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8
Q

what questions should you ask yourself when interpreting rhythm

A
  • is it regular or irregular
  • if its irregular is it irregularly irregular or regularly irregular
  • is there a P for every QRS
  • is there a QRS for every P
  • are there Ps and the QRSs consistently and similarly related
  • are all the Ps alike
  • are all the QRSs alike
  • are the QRSs narrow and upright in leads 2/3/avf
  • are the QRSs wide and bizarre
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9
Q

describe normal sinus rhythm

A
  • normal impulse originates in the SA node
  • The SA node has an inherent pacemaker rate of 70-160 bpm in the dog and 160-240 bpm in the cat
  • P waves are usually positive in lead 2
  • the PR interval is usually consistent from beat to beat
  • the QRS complex is usually “normal”
  • the rhythm may be regular or irregular
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10
Q

describe sinus arrythmia

A
  • as normal sinus rhythm except greater variation in P-P or R-R interval
  • then rhythm is irregular but regularly so
  • if related to the respiratory cycle = respiratory sinus arrhythmia (normal in the dog, abnormal in the cat) mediated by fluctuations in vagal tone, abolished by giving atropine, accentuated by vagal manoeuvres
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11
Q

what is bradydysrhythmia

A

heart rate lower than normal

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12
Q

what is sinus arrest

A
  • failure of pacemaker to discharge
  • pause with no P-QRS-T complex
  • heart does not stop!
  • next fastest pacemaker takes over
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13
Q

what is persistent atrial standstill

A
  • a type of bradydysrhythmia
  • there is a complete absence of P waves
  • next fastest pacemaker takes over
  • the heart rate is usually slow but regular
  • QRST - normal - junctional escape rhythm
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14
Q

what is a first degree AV block

A
  • a type of bradydysrhythmia
  • P wave and QRS complex are normal
  • the P-R interval is prolonged
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15
Q

what is a second degree AV block

A
  • a type of bradydyrythmia
  • P wave not conducted through the AV node = p without QRS
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16
Q

what is a complete (third) AV block

A
  • a type of bradydysrhythmia
  • persistent failure of conduction through AV node
  • ventricles usually paced (depolarisation originating) from ventricular focus
  • wide, bizarre escape complexes at approx 30-40 min (dog)
17
Q

what is tachydysrhythmia

A
  • heart rate is higher than “normal”
  • ectopic activity
  • key part of interpretation is to establish origin of abnormal activity
18
Q

what is seen in supraventricular prematuer complexes

A
  • premature P wave (P’ wave) interrupts normal P wave rhythm
  • P’ wave is early I compared with a normal p-p interval)
  • P’ wave configuration differs from the normal P waves
  • QRST usually normal
19
Q

describe what happes in a normal ECG wave at each point

A
20
Q

what is seen in supraventricular tachycardia

A
  • runs of more than three consecutive supraventricular premature complexes
  • heart rate during tachycardia is greater than upper normal limit
  • rhythm during tachycardia is usually regular
  • site of origin is within atria/junction outside of SA node
  • P’ waves differ from the “normal” sinus P wave (if availible)
  • maybe sustained (>30s) or non-sustained (paroxysmal, <30s)
  • P’-P’ interval is normally regular
  • P’-R interval is normally constant IF every P’ wave is conducted
  • QRS is usually “normal” - narrow and upright in lead 2
21
Q

describe what occurs in atrial fibrillation

A
  • heart rate may or may not be within normal limits
  • rhythm is irregularly irregular (very obvious on auscultation)
  • no isoelectircal baseline
  • No P waves
  • irregular, variable amplitude fibrillation waves may be evident
  • QRS complex is usually “normal” - narrow, upright in lead 2
  • usually sustained, maybe non-sustained (paroxysmal)
22
Q

what happens during ventricular premature complexes

A
  • AKA ventricular ectopics
  • site of origin is within ventricles
  • rhythm is irregular
  • wide and bizarre QRST complex interrupts rhythm
  • spread through myocardium, NOT conducting tissue
  • usually the underlying NSR is undisturbed
  • VPC QRST unrelated to P waves
  • VPS QRST complex voltage is usually large
23
Q

What is bundle branch block wide and bizarre complex

A

passive spread, conducting system damaged

24
Q

describe ventricular tachycardia

A
  • a run of 3 or more ventricular premature complexes
  • rhythm usually regular during tachycardia
  • rate low but > intrinsic rate of the ventricles (>40 bpm in the dog, >60 bpm in the cat)
  • may be sustained or not sustained

SA node still firing

25
Q

describe ventricular fibrillation

A
  • usually terminal
  • rhythm associated with cardiopulmonary arrest
  • heart rate rapid and irregular
  • no isoelectric baseline
  • ECG is irregular and chaotic
  • no recognisable PQRST complexes
  • course or fine depending on the degree of baseline oscillation