Abnormal ECG Flashcards

1
Q

Rhythm arising from the SA node, Atrium or AV node are called…

A

Supraventricular rhythm

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2
Q

How are the Supraventricular rhythms conducted and what is the consequence on ventricular depolarisation?

A
  • By His-Purkinje system

- Normalventricular depolarisation ,normal narrow QRS

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3
Q

Where do ventricular rhythms arise from and how do they spread ?
What do QRS look like ?

A
  • From different foci in ventricle
  • DONT spread via His-Purkinje system
  • Wide QRS (>3 small boxes)
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4
Q

What do atrial beats look like on ECG ?

A
  • Small p wave

- Normal QRS

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5
Q

What can you see on a AV junctional beat ECG ?

A

Reversed p wave because atrial depolarisation goes away from apex (AV to SA)

Normal QRS

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6
Q

Which lead is the best to look at p waves ?

A

II

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7
Q

What is normal sinus rhythm ?

A
  • HR 60-100 bpm
  • Regular
  • p wave befor each QRS
  • PR 0,12-0,20 s
  • QRS < 0,12 s (3 small boxes)
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8
Q

Sinus rhythm with rate < 60bpm is called …

A

Bradycardia

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9
Q

What causes Atrial Fibrillation ?

A

Multiple atrial foci , chaotic impulses

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10
Q

What are the consequences of AF on the P wave , impulse and QRS ?

A
  • No p wave , wavy baseline
  • Impulses arrive at AV node at rapid irregular rate
  • QRS normal but irregular
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11
Q

In AF, are all impulses arriving at the AV node conducted ? Why

A

No,

only some at irregular intervals because AV node in refractory period

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12
Q

How is the pulse and HR in AF ?

A

Irregularly irregular

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13
Q

What is Heart block ?

A

AV conduction blocks

-Delay or failure of impulse conduction from atrium to ventricle via AV node and bundle of HIS

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14
Q

What can cause heart block ?

A

Acute MI

Degenerative changes

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15
Q

What are the 3 types of heart block ?

A
  • First degree
  • 2nd degree
  • -type 1 : Wenkenbach
  • -type 2
  • 3rd degree , Complete heart block
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16
Q

Describe ECG for First degree heart block

A
  • P wave normal
  • Prolonged PR interval (>5 small squares)
  • QRS normal
17
Q

Describe ECG for 2nd degree heart block TYPE 1

A
  • Progressive lengthening of PR interval
  • Until one P not conducted (Missing QRS)
  • Then new cycle of lengthening (can be 2:1 …)
18
Q

What happens on an ECG showing 2nd degree TYPE 2 heart block?

A

-Normal PR interval
-Sudden non-conduction of beat : Dropped QRS
(Skipped ventricular beat)

19
Q

What happens in Complete heart block ? (Atrial Depolarisation, ventricle, impulse,HR)

A
  • Normal atrial depolarisation
  • Impulse not conducted to ventricles
  • Ventricle pacemaker takes over : Ventricular Escape rhythm
  • HR slow , poor BP
20
Q

What does the ECG look like if Complete heart block ?

A
  • P wave normal
  • P-P interval constant
  • QRS interval wide
  • R-R intervals constant but slow (37bpm)
  • No relationship between p and QRS
21
Q

What causes an single abnormal wide QRS complex in ECG and why is it wide ?

A
  • Ventricular ectopic beat du to ectopic focus in ventricular muscle
  • QRS wide because slow because not spread through His-Purkinje system
22
Q

How is Ventricular ectopic beat different from Ecape rhythm in 3rd degree heart block?

A

Wide QRS complex not regular.

23
Q

Define Ventricular tachycardia

A

Run of more than 3 consecutive ventricular ectopic beats (broad complex tachycardia )

24
Q

What is ventricular fibrillation ? What is the cause ?

A
  • Abnormal , chaotic , fast ventricular depolarisation

- Due to impulses from numerous ventricular ectopic foci

25
Q

What is the consequence of VF on contraction and CO ?

A
  • No contraction (ventricles quiver)

- No CO, cardiac arrest

26
Q

Which lead face the Inferior part of the heart ?

A

II , aVF, III

27
Q

Which lead face the Anterior part of heart ?

A

V3, V4

28
Q

Which lead face the Septal region ?

A

V1, V2

29
Q

Which part of the heart is faced by aVL, I, V5 andV6?

A

Lateral (left)

30
Q

Which part of the myocardium is most vulnerable to Ischaemia and MI ?

A

Sub endocardial muscle

31
Q

What are the consequence of Ischaemia on ECG, why ?

A

-ST segment depression
-T wave inversion
Due to abnormal current in Repolarisation

32
Q

Are they Q waves in Ischaemia ?

A

No

33
Q

What is MI ?

A
  • Muscle injury extends to full thickness form Endo to Epi cardium
  • Due to complete occlusion of lumen of coronary arteries
34
Q

What can you seen ECG if MI?

A

ST elevation ,abnormal repolarisation current

35
Q

What happens to myocardium and ECG if prolonged MI ?

A
  • Muscle Necrosis

- Q wave

36
Q

pathological Q waves measurement ?

A

> 1 small square wide (>0,04 s)
2 small squares deep (>2mm)
Depth more than 1/4 of R wave

37
Q

What happens in Hyperkalaemia ? (RMP and ECG)

A
  • RMP less negative (more depolarised, close to threshold )
  • High T wave
  • then PR interval , depressed ST, high T
  • no p wave
38
Q

ECG changes in Hypokalaemia ?

A
  • Low T wave ,

- High U wave