ECG's Flashcards
What does 1 small square, 1 large one and 5 large squares represent?
Remember, the whole strip is 12 seconds long!
- 04s
- 2s
1 second
OR JUST DIVIDE 300 BY THE NUMBER OF LARGE SQUARES BETWEEN EACH QRS PEAK
What are the 4 steps for reading an ECG?
- Rate
- Rhythm using rhythm strip
- Axis (I, II, III)
- P wave
- PR interval 6,7,8,9,10, etc…..
SLIDES
How do you calculate the rate?
Rhythm - what do the following mean in terms of ECG’s?
Sinus tachycardia
AF
Atrial flutter - what does this look like on ECG?
Number of QRS peaks x5 or 300 divided by number of large squares
Inc/dec with inspirations - regularly irregular
Irregularly irregular
Sawtooth baseline
Axis:
What 3 leads do you look at?
What causes LV deviation?
What causes RV deviation?
Lead I, II, III
LVH*
Hemiblock
MI
WPW syndrome
RVH*
Hemiblock PE MI WPW syndrome Tall thin person
Chest leads:
How does the QRS complex progress from V1 to V6?
Why is the transition period important?
What part of the heart do the following leads represent:
- V1 & V2
- V3 & V4
- V5 & V6
Mainly downwards to mainly upwards
Can indicate some enlargement of the ventricles
Septum
Anterior
Lateral
THE CHEST LEADS BASICALLY LOOK MAINLY AT THE LEFT SIDE OF THE HEART!
What is tachycardia?
Causes - list some
> 100bpm
Infection Pain Exercise Anxiety Dehydration Bleed etc.
What is sinus bradycardia?
Causes - list some
<60 bpm
Physical fitness Vasovagal attacks Drugs (Beta-blockers, digoxin) Hypothyroidism Hypothermia
What is a normal PR interval?
What is a normal QRS complex length?
3-5 small squares
0.12 - 0.2 seconds
3-5 small squares
0.12 - 0.2 seconds
1st degree HB - what is it?
What about Rx?
Causes:
- What heart disease causes this? -2
- What causes abnormal electrical activity everywhere?
- What cardiac drug at toxic levels can cause this?
PR interval >0.2 seconds - 5 small squares
No Rx needed
Coronary artery disease
Acute rheumatic carditis
Electrolyte imbalance
Digoxin toxicity
2nd degree HB - Mobitz type 1/Wenckebach
What is it?
Rx?
Progressively prolonged PR interval until P wave fails to transmit to ventricles
No Rx needed
2nd degree HB - Mobitz type 2
What is it?
What does this type increased the risk of?
Rx?
Constant PR interval but intermittent failure to transmit to ventricles
High risk of progression to 3rd degree block so often requires pacemaker Rx
3rd degree HB - Complete HB
What is it?
What happens to the QRS?
Rx?
How can an MI of the RIGHT CORONAY ARTERY cause this?
No transmission of p waves in ventricles with a ventricular escape rhythm taking over
QRS is usually wider but can be narrow if Bundle of His takes over as pacemaker
Requires pacemaker
The AVN is supplied by the posterior interventricular artery, which in the majority of patients is a branch of the right coronary artery.
In the remainder of patients the posterior interventricular artery is supplied by the left circumflex artery.
QRS complex:
What is classed as a narrow QRS?
What is classed as a wide QRS?
QRS is classed as tall if the are > 5mm in the limb leads AND > 10mm in the chest leads.
What does tall QRS’s suggest?
<0.12 seconds
> 0.12 seconds
Hypertrophy
QRS complex:
What is a delta wave?
The ventricles are being activated earlier than normal from a point distant to the AV node.
The early activation then spreads slowly across the myocardium causing the slurred upstroke of the QRS complex.
Note – the presence of a delta wave does NOT diagnose Wolff-Parkinson-White syndrome. This requires evidence of tachyarrhythmias AND a delta wave.
https://geekymedics.com/how-to-read-an-ecg/
QRS complex:
A pathological Q wave is > 25% the size of the R wave that follows it or > 2mm in height and > 40ms in width.
What does a pathological Q wave suggest?
What wave of the Q, R and S should become bigger as you go from lead V1 to V6?
If this increase is not seen, what does it suggest?
Previous MI
R should become bigger - so negative to positive
Previous MI
QRS complex:
The J point is where the S wave joins the ST segment.
This point can be elevated resulting in the ST segment that follows it also being raised (this is known as “high take-off”).
High take-off (or benign early repolarisation to give its full title) is a normal variant that causes a lot of angst and confusion as it LOOKS like ST elevation.
How would you know it is not a STEMI?
High take off occurs mostly under the age of 50 (over the age of 50, ischaemia is more common and should be suspected first).
Typically, the J point is raised with widespread ST elevation in multiple territories making ischaemia less likely.
The ECG abnormalities DO NOT CHANGE! During a STEMI, the changes will evolve – in benign early repolarisation, they will remain the same.
The T waves are also raised (in contrast to a STEMI where the T wave remains the same size and the ST segment is raised).
https://geekymedics.com/how-to-read-an-ecg/
Read section on this
Key points for assessing the J point segment:
Benign early repolarisation occurs mostly under the age of 50 (over the age of 50, ischaemia is more common and should be suspected first).
Typically, the J point is raised with widespread ST elevation in multiple territories making ischaemia less likely.
The T waves are also raised (in contrast to a STEMI where the T wave remains the same size and the ST segment is raised).
The ECG abnormalities do not change! During a STEMI, the changes will evolve – in benign early repolarisation, they will remain the same.
Key points for assessing the J point segment:
Benign early repolarisation occurs mostly under the age of 50 (over the age of 50, ischaemia is more common and should be suspected first).
Typically, the J point is raised with widespread ST elevation in multiple territories making ischaemia less likely.
The T waves are also raised (in contrast to a STEMI where the T wave remains the same size and the ST segment is raised).
The ECG abnormalities do not change! During a STEMI, the changes will evolve – in benign early repolarisation, they will remain the same.
ST-segment:
It is normally meant to be an isoelectric line. What does it mean?
ST-elevation is significant when it is greater than 1 mm (1 small square) in 2 or more contiguous limb leads or >2mm in 2 or more chest leads.
What does ST-elevation suggest?
ST depression is ≥ 0.5 mm in ≥ 2 contiguous leads. What does ST depression suggest?
Neither elevated nor depressed
Acute full thickness MI
Ischaemia
When remembering measurements, remember that chest leads are always double number of mm compared to the limb leads as they are closer to the heart.
T waves:
What are T waves representing?
T waves are classed as tall if the are > 5mm in the limb leads AND > 10mm in the chest leads (same as QRS).
What does tall T waves suggest? - 2
Repolarisation of ventricles
Hyperkalaemia - tall tented T waves
Hyperacute STEMI
T waves:
In what limb lead AND in what chest lead is T wave inversion normal?
What drug toxicity closes T wave inversion?
Lead III and V1 - they are on the right side so more likely to be negative.
T wave inversion is a non-specific sign for a variety of conditions:
- Ischaemia
- Bundle branch blocks (V4-6 in - - LBBB and V1-V3 in RBBB)
- Pulmonary embolism
- Left ventricular hypertrophy (in the lateral leads)
- Hypertrophic cardiomyopathy (widespread)
- General illness
Digoxin toxicity - at high doses
T waves:
Biphasic T wave:
What is it?
Ischaemia is a cause.
What electrolyte imbalance cause this?
There are 2 peaks basically
Hypokalaemia
Supraventricular rhythm
What is it?
4 types - name them?
What would you see on the ECG?
Abnormally fast heart rhythm arising from improper electrical activity in the upper part of the heart.
Atrial fibrillation
Paroxysmal supraventricular tachycardia (PSVT)
Atrial flutter
Wolff–Parkinson–White syndrome
Narrow QRS complexes
Inverted - ectopic atrial tachycardia
Varying morphology
Sawtooth - AF
Ventricular rhythm
What is the cause of this? - 1
What do you see on ECG? - 1
What could happen to the p-waves?
Complete heart block
Wide/broad QRS
P waves and QRS at different rates so p-waves are often hidden behind QRS complexes.
What effect does digoxin have on ECG’s
T wave inversion if it reaches toxic levels
