Cardiac monitoring and rhythm recognition Flashcards
What is an ECG?
Recording of electrical activity within heart.
Normal ECG will demonstrate electrical activity through normal conduction pathways.
What is a myocardial fibre contraction?
Contraction of heart
Occurs simultaneously with electrical activity.
State the movement of electrical activity in a heart beat
- Sinoatrial node
- Atrioventricular node
- Atrioventricular bundle (bundle of his)
- Right and left bundle branches
- Purkinje fibres
What is a lead in reference to ECG?
Refer to electrical activity between two points. (ECG normally three leads used)
Standard lead II used for monitoring as allows for positive deflection of the heart.
- Right just below the clavicle (red)
- Left side below clavicle (yellow)
- Left side on leg (green)
Where should the red lead go in an ECG?
Right just below the clavicle
Where should the yellow lead go in an ECG?
Left side below clavicle
Where should the green lead go in an ECG?
Left side on leg
What are some potential problems in recording an ECG?
- Poor contact eg. Sweating
- AC interference (eg. Other machines nearby)
- Patient movement (shivering)
- Gain set inappropriately
- Paper speed set incorrectly/ not checked
- Leads attached incorrectly
On ECg paper what does one small square indicate?
0.04seconds
On ECG paper what does 1 large square signify?
0.2 seconds
5 small squares
On ECG paper what does 5 large squares signify?
1 second
What does the P wave signify on an ECG reading?
SA node firing
Atrial depolarisation
What is the P-R interval?
What is the normal size for this?
Time it takes for the AV node contraction
Normal = 3-5 small squares (0.6-1second)
What can it signify if a P-R interval is longer than 5 small squares?
Arythmia
eg.
1st degree heart blood
Prolonged P-R interval
Normal - 3-5 small squares
What is the QRS interval and how big is a normal QRS interval?
Signifies right and left ventricular depolarisation
Should be thin and quick
Normally less than 3 small squares
What can it signify if the QRS interval is longer than normal?
If wider than 3 small squares
There is a delay in conduction in ventricular conduction
Can signify a bundle branch block
What is the T wave?
Ventricle Depolarisation
What is the PR interval?
Time between atrial and ventricular depolarisation
AV node conduction
What is the structured approach for accessing the rhythm of an ECG?
- Is there electrical activity (has it been done correctly)
- Is it regular
- What is the rate
- Are there P waves/ atrial activity
- What is the PR interval
- What shape is the QRS complex
How can you assess the rate of a heart beat using ECG?
Check that ECG paper speed is set at 25mm/sec
300 large squares is one minute
Number of large squares between R waves and divide by 300
Eg. 300/4 = 75bpm (normal sinus rhythm)
CHECK THAT THE R WAVES ARE REGULAR
What questions should we be asking to assess the P wave and atrial activity?
- Are there identifiable P waves?
- Do the P waves have normal morphology (shape)?
- Are there P waves before every QRS complex?
- Is every P wave followed by QRS complex?
How would you assess the PR interval?
- Measure from beginning of P wave to first deflection of QRS complex
- Normal duraction 0.12-0.20 seconds (3-5 small squares)
- PR interval greater than 0.2 seconds indicated block at AV node
- Short PR interval indicated abnormally fast conduction
How would you assess a QRS complex?
- Normal duration is 0.12 seconds (less than 3 small squares)
- Ford QRS complex follow every P wave?
- Is the complex wide or narrow?
- Is the morphology (shape) normal?
What would a wide QRS indicate?
Abnormal electrical activity through abnormal pathways
Slow conduction
Associated with ineffective myocardial contraction and reduced cardiac output
State three cardiac arrest rhythms
- asystole
- ventricular fibrillation
- ventricular tachycardia
Explain teh characteristics of asystole?
- Cardiac arrest
- Wandering baseline (not actually flat)
- No identifiable atrial or ventricular activity
- No cardiac output
State the characteristics of ventricular fibrillation
• Chaotic ventricular activity
• No cardiac output – cardiac arrest
• Cardiac arrest rhythm
- No blood being pumped from the heart (no QRS wave)
Explain the characteristics of atrial fibrillation
• Irregularly irregular
• Ventricular rate variable
• No identifiable P wave
• Fibrillation wave – very common
• Blood clots form – this can move through body and cause stroke
• Chaotic atrial activity with intermittent atrioventricular conduction
- QRS complex narrow
State the characteristics of ventricular tachycardia
• Regularly irregular rhythm
• Wide – from ventricles
• No P waves
• Tachycardia
• Can cause cardiac arrest but not always
• Rate 100-300bpm
Define bradycardia
P-T wave spread out (less than 60) – whole wave
Define tachycardia
P-T wave close together (more than 90) – whole wave
State the two types of cardiac arrest
STEMi
Non-STEMI
Whats the difference between teh two types of cardiac arrest?
STEMI - ST segment elevation - ST segment moved up - this caused by acute myocardial infarction
Non-STEMI - no ST segment elevation - so ST segment depression
