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Clinical and Ethics MD3001 > ECG Interpretation > Flashcards

ECG Interpretation Flashcards

1
Q

How do you calculate rate?

A

300 divided by the number of big squares between each QRS complexes

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2
Q

What are the four criteria’s for sinus rhythem?

A
  • Are normal P waves present (shorter than 0.25mm and upright in 1/2/3)
  • Are the QRS complex narrow (less than 0.12s) or wide (more than 120ms)
  • P wave ALWAYS come before a QRS complex
  • Is the rhythm regular or irregular
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3
Q

How can you physically tell if the rhythm is regular

A

Mark positions of 3 successive R waves then slide marker along to check intervals are equal

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4
Q

Describe what is seen on an EGC for atrial fibrillation

A

There are no visable P wave and irregular QRS complexes

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5
Q

How does atrial flutter appear on ECGs?

A

Where P waves are seen at a rate of 300BMP giving saw tooth appearance.

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6
Q

What does a normal P wave look like?

A

Less than o.25mV in height and it deflects upwards in leads 1, 3 and AVF

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7
Q

In what defects are the P waves absent?

A

Atrial fibrillation and Nodal rhythm

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8
Q

Name and describe an abnormal P wave

A

P-mitrale - Bifid P waves that indicate left atrial hypertrophy.
P-Pulmonale - Peaked P wave which indicates right atrial hypertrophy.

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9
Q

How to you measure the P-R interval?

A

From beginning of P wave to beginning of Q wave. Normal range is 0.12-0.2s.

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10
Q

A prolonged P-R imples?

A

Delayed AV conduction

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11
Q

How do you measure the QRS complex and what does a normal QRS complex look like?

A

From beginning of Q wave to end of S wave. Normal duration - 0.12s and the normal Q wave is 0.04s and less than 2mm depth.

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12
Q

If the QRS wave lasts for longer than 0.12s what does this indicate?

A

Ventricular conduction defects such are left and right bundle branch defects

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13
Q

If the voltage of the QRS complex is below 5mm then what does this indicate?

A

Hypothyroidism, COAD (chronic obstructive airway disease), myocarditis, pericarditis and pericardial effusion.

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14
Q

How does left ventricular hypertrophy appear on an ECG and is the most common cause?

A

R wave in V5 is bigger than 25mm. This is most often due to high blood pressure

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15
Q

How does right ventricular hypertrophy appear on an ECG?

A

Dominant R wave in V1, T wave inversion in V1-V3 or V4, and Deep S wave in V6

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16
Q

What is a significant Q wave defined as and when might you see this

A
  • Longer than 0.04s and deeper than 2mm. It can be present a couples hours/days after acute MI and if its present in lead 3 then consider PE.
17
Q

How calculate the correct QTc intercal?

A

QT/Square root of RR interval.

18
Q

What can cause a prolonged QT interval?

A
  • Acute myocardial ischaemia,
  • Myocarditis,
  • Bradycardia,
  • Hypothermia,
  • U&E imbalance,
  • Congenital
  • Drugs
19
Q

What is the ST segment?

A

Time from end of ventricular depolarisation to the start of ventricular repolarisation. Usually isoelectric (sits at baseline)

20
Q

Describe when you have an abnormal ST segment and why this might occur

A
  • If there is elevation in two adjacent limb or chest leads then indicates infarction.
  • If the st segment is depressed then it indicates ischaemia
21
Q

Describe the normal and abnormal inverted T wave

A

Normal - aVR, V1 and (V2 in young folk)

Abnormal - Inversion all other leads (ischaemia/infarction)

22
Q

What are the effects of digoxin

A

T wave inversion and ST segment sloping depression

23
Q

What is the cardiac axis?

A

Average direction of spread of the depolarisation wave through the ventricles. Normal axis means all QRS complexes in leads 1-3 deflect up with lead 2 having the highest peak.

24
Q

Describe what occurs when there is deflections in the cardiac axis

A

If there is left axis deviation - there will be negative deflections in lead 2 and 3. Indicates LV hypertrophy or MI.
If there is right axis deviation then there will be negative QRS deflections in lead one. Indicates RV hypertrophy, PE or MI

25
Q

Describe the MI ECG changes

A
  • T wave peaked followed by T wave inversion.
  • ST elevation.
  • Appearance of new Q waves
26
Q

Describe how you can use the ECG to localise the infarct causing the Infarct

A

Anterior infarction - Any precordial (chest) leads
Lateral infarction - Leads 1, AVL, V5 and V6.
Inferior - Leads 2, 3,and AVF
Posterior - Reciprocal changes in lead V1

27
Q

Describe how pulmonary embolism presents on ECG

A

Large S wave in lead 1,

Deep Q wave in lead 3 and inverted T wave in lead 3

28
Q

How do hyperkalaemia and hypokalaemia show on ECG?

A

Hyper - Tall, tented T waves and widened QRS.

Hypo - Small T waves and prominent U wave

29
Q

How does hyper/hypocalcaemia present on ECGs

A

Hyper - Short QT interval,

Hypo - Long QT interval and small T waves

Clinical and Ethics MD3001 (26 decks)

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