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Med 1 Block > ECG interpretation > Flashcards

ECG interpretation Flashcards

1
Q

Describe the stepwise process you would use to interpret an ECG

A

Rate
Rhythm
Axis
P wave
PR interval
QRS
ST segment
T wave

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2
Q

What does each section of the ECG represent?

A

P wave = atrial depolarisation
PR interval = time for electrical activity to pass between the atria and the ventricles
QRS complex = ventricular depolarisation
T wave = ventricular repolarisation
ST segment = delay between ventricular depolarisation and repolarisation
QT interval = time take for ventricles to fully depolarise and repolarise

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3
Q

What is the normal length of the PR interval?

A

120-200ms around 3 to 5 small sqaure

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4
Q

What is the normal length of the QRS complex?

A

Up to 3 small sqaures, aka less than 0.12 milliseconds
Lowest = 0.08 ms

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5
Q

If the QRS is abnormal, what part of the cardiac cycle is not functioning as normal?

A

Ventricular depolarisation = ventricular contraction

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6
Q

If the P waves are abnormal what part of the heart is not functioning effectively?

A

Atrial depolarisation

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7
Q

If the PR interval is lenghted what does this indicate what does this mean is happening to electrical activity within the heart?

A

Indicates a delay in the transferance of electrical activity from the atria to the ventricles = AV block

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8
Q

If the PR interval is shortened what does this indicate is happening to the electrical activity within the heart?

A

Faster conduction of electrical activity from the atria to the ventricles
A) smaller heart
B) SAN located closer to the AVN
c) accessory pathway for electrical activity to pass from the atria to the ventricles rather than passing through the AVN - e.g WPWS

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9
Q

Is the QRS complex if lengthened what does this indicate is happening to the electrical activity within the heart?

A

A broad QRS = abnormal/longer time for depolarisation = BBB or ventricular ectopics
Increased QRS voltage = left ventricular hypertrophy

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10
Q

What are the different causes of an ST elevation?

A

Acute myocardial infarction
Coronary vasospam
Pericarditis
Benign early repolarisation
Left bundle branch block
Left ventricular hypertrophy
Ventricular aneursym
Raised ICP
Takotsubo cardiomyopahty
Brugada syndrome.

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11
Q

What ECG leads align with what territories of the heart?

A

1 - lateral
2 + 3 = inferior
AvR =
AvL = lateral
AvF = inferior
V1 + V2 = septal
V3, +V4 = anterior
V5 + V6 = lateral

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12
Q

What is the blood supply to the inferior region of the heart?
What ECG leads does this relate to?

A

Leads 2,3,aVF
Right coronary artery (90%)
Left circumflex artery (10%)

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13
Q

What is the blood supply to the lateral view of the heart?
What ECG leads does this relate to?

A

Leads 1, AVL, V5,V6
Left coronary artery - specifically the circumflex artery For mainly lead 1 and AVL
Lead V5 and V6 - distal LAD, left circumflex or RCA.

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14
Q

What is the blood supply to the anterior region of the heart?
What ECG leads does this relate to?

A

The left coronary artery, specifically the distal LAD

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15
Q

What is the blood supply to the septal region of the heart?
What ECG leads does this relate to?

A

Leads V1 and V2
The proximal LAD.

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16
Q

How is time shown on an ECG?

A

Small square = 0.04 seconds
Large square = 0.2 seconds
5 large squares = 1 second
300 large squares = 1 minute

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17
Q

What are some common causes of right axis deviation?

A

RALPH
Right ventricular hypertrophy
Anterolateral MI
LPH - left posterior hemiblock

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18
Q

What are some common causes of left axis deviation?

A

VILLA
Ventricular tachycardia
Inferior MI
Left ventricular hypertrophy
Left anterior fasicular block

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19
Q

In relation to P waves, if absent what baseline activity indicates what pathology?

A

Flutter = sawtooth baseline
Fibrillation - chaotic baseline

20
Q

What is the relationship between ST Depression and ST elevation?

A

Can be reciprocal
posterior STEMI can have ST depression in V1-v3.

21
Q

What are the different ways you can calculate the HR on an ECG?

A

For reg = 300/number of large squares between R-R interval

For irreg = 6*no.QRS complex over rhythm strip

22
Q

What are the different types of heart rhythm?

A

Regular = QRS and T wave follow a regular pattern
Reg Ireg = recurrent irregular pattern (1st degree HB)
Ireg Ireg = completely disorganised

23
Q

What is meant by the cardiac axis?

A

The overall direction of electrical spread within the heart

24
Q

What is the normal cardiac axis?

A

Between -30 to 90 degrees
Most positive deflection in lead 2, may also be positive in Lead 1, aVR tends to be negative

25
Q

What is meant by right axis deviation?
What can cause this?
How to identify on an ECG?

A

Main depolarisation vector is distorted to the right (+90 and +180)
Can be caused by right ventricular hypertrophy (pulmonary HTN)
Neg lead 1, Post lead 3 (most) and AvF
Lead 3 and Lead 1 point towards each other (arriving)

26
Q

What is meant by left axis deviation?
What can cause this?
How can this present on an ECG?

A

The main depolarisation vector is to the left.
Cause - left ventricular hypertrophy
ECG - lead 1 is positive, lead 3 and Lead 2 is negative - Lead 1 and lead 2 are Leaving

27
Q

What is the key indication of Atrial Fibrillation on an ECG?

A

Absent P waves and irregular irregular rhythm.

28
Q

How do the different types of heart block present on an ECG?

A

1st - fixed prolonged PR interval always followed by a QRS
2nd type 1 - progressively prolonged PR int with QRS drop, then repeat
2nd type 2 - constant PR interval duration with intermittent QRS drop often every 3 or 4
3rd - no relationship between pattern of P waves and QRS complexes.

29
Q

How does Wolff-Parkinson-White syndrome typically present on an ECG?

A

Shortened PR interval
Delta wave (slow rise to QRS) caused by accessory pathway between atria and ventricles.

30
Q

What are the key presentations of a BBB in an ECG?

A

WiLLiaM MaRRoW
Left - W in V1 M in V6
Right - M in V1 rSR’ and W in V6 where s is slurred

31
Q

What is the definition of an ST elevation?

A

> 1mm (1 small square) in 2 or more contiguous (looking at the same area of the heart) limb leads or 2mm in 2 chest leads.

32
Q

Define ST depression

A

> 0.5mm in 2 or more contigous leads

33
Q

What is Brugada syndrome?
How is this shown on an ECG?

A

Inherited Channelopathy - disease of myocardial sodium channel leads to paroxysmal ventricular arrhythmias and sudden cardiac death in young patient
Brugada sign = ST elevation and partial RBBB in V1-2 with a coved appearance

34
Q

What is a tall T wave?
What are some causes?

A

> 5mm in limb leads and >10mm in chest leads
Tepee

35
Q

What are some causes of an inverted T wave?

A

Normal in V1
Can be normal in Lead 3
Pathological causes include = Pe, ischaemia, BBB, LVH and HOCM.

36
Q

What can cause a flattened T wave?

A

Ischaemia
Electrolyte abnormalities

37
Q

What is the key sign of hyperkalemia on an ECG?

A

Tall, narrowed, T waves - like a teepee

38
Q

What is shown on this ECG?

A

Ventricular tachycardia

39
Q

What is shown on this ECG?

A

Ventricular fibrillation

40
Q

What is shown on this ECG?

A

Torsades de pointes

41
Q

What rhythms are common during cardiac arrest?
Which of these are shockable

A

Ventricular tachycardia and ventricular fibrillation are shockable.
Asystole and pulseless electrical activity are not shockable.

42
Q

What are the different causation categories of SVT?

A

Abnormalities of impulse conduction (re-entrant tachycardias)
Disorders of impulse initiation (automatic tachycardia) causing a narrow complex tachycardia
Regular rhyhtm.

43
Q

What are the ECG changes seen in lithium toxicity?

A

Inverted T waves
Sinus bradycardia
PR prolongation
Brugada sign - ST elevation in V1-3 followed by T wave inversion
Sinoatrial Block
Intraventricular conduction delays (QT prolongation)

44
Q

What ECG changes are seen in digoxin toxicity?

A

ST depression (tick sign) followed by a flattened or inverted T wave

45
Q

What ECG changes are seen from SSRIs?

A

QT prolongation

46
Q

What ECG changes are seen in anti-psychotic toxicity?

A

QT prolongation and lethal cardia arrhythmias.

Med 1 Block (39 decks)

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