ECG Flashcards
What does ECG stand for?
Electrocardiograph or electrocardiogram
What is an ECG?
Recording of the electrical activity of the heart
What are the placements for 3 lead ECG?
RA - Right Arm
LA - Left Arm
RL - Right Leg
LL - Left Leg
What is Eithonven’s Triangle? (4)
It is an imaginary formation of three lung leads in a triangle using an ECG, formed by the two shoulders and the pubis.
The shape forms an equal lateral triangle with the heart at the centre.
The top part of the triangle is lead 1 from the right arm to the left arm.
The right hand region is lead 2 from the right arm to the left leg.
The left hand region is lead 3 from the left arm to the left leg.
When is an ECG used?
Investigate symptoms of possible heart problems, such as chest pain, palpitations (suddenly noticeable heartbeats), dizziness and shortness of breath.
Prior to surgery or drug treatment
In the assessment of collapsed patient or in cardiac arrest
What can ECGs help detect?
Arrhythmia - bradycardia, tachycardia, atrial fibrillation, ectopic?
Coronary heart disease - heart blood supply is blocks or interrupted by build up of fatty substances
Heart attacks - where supply of blood to heart is suddenly blocked
Cardiomyopathy - heart walls become thickened or enlarged
What is a three lead ECG commonly used for?
Commonly used for gross rhythm abnormality assessment in cardiac arrest and for continuous monitoring
When is a 12 lead ECG used?
Most commonly used for diagnostics in acute coronary syndromes and cardiac assessment.
What are some positives of ECGs?
Represents data in graphical form (visible)
Informative and provides information such as chest pain, shortness of breath, abnormal pain etc
Can detect silent cardiac condition which could be result of surgery or anaesthesia
Safe method
Non-invasive
Inexpensive
Easy to perform
Equipment widely available
What are some disadvantages of ECGs?
Provides graph which may not reflect severe underlying heart issues
Wires and probes for testing. May be uncomfortable and restricts body movements
No all heart problems would be detected, eg. A vulnerable plaque which is a form of atheroma. Because artery walls enlarge in response to enlarging plaques they do not affect blood flow and may not be detected on ECG but is major cause of heart attacks
What are the main components of ECGs?
P Q R S T
What is the P wave?
A small deflection representing the depolarising of the atria
How many squares does a p wave normally take?
2-3 small squares
What is the PR interval?
Beginning of P wave to the beginning of the QRS complex
How many boxes is taken at the PR interval?
3-5 boxes
What is the QRS complex?
Represents ventricular depolarisation
Q wave is the first negative deflection and is not always present
How many boxes is taken at the QRS complex?
1-3 boxes
What is a T wave?
A small rounded deflection (asymmetric) and is due to depolarisation is the ventricles
What is lost in the QRS complex and nit visible?
Atrial repolarisation
Is depolarisation positive or negative?
+40mV
Is repolarisation negative or positive?
Negative
Why is a T wave positive?
The septum and deep endocardium areas do depolarise first but they have a longer period of contraction
Therefore most of the outer surface of the ventricles, especially near the apex are the first to repolarise
What happens to QT intervals as the heart rate increases?
Shortens
What happens to QT intervals when Drugs is taken or the patient has a disease?
Shortens
What is important about the ST segment that should be taken into consideration ?
Should come back to the iso-electric line
What do U waves represent?
A wave of late repolarisation
How do you calculate heart rate?
Divide 390 by the number of large squares (0.2 sec) between R-R intervals.
THIS ONLY APPLIES TO REGULAR RHYTHMS
Use the 10 second rule
Illustrate the 10 point plan:
What is the heart rate?
Is it regular?
Are the P waves present?
Are the P waves all the same size and shape?
Is there a P wave before every QRS complex?
Is there a QRS complex after every P wave?
Is the PR interval normal?
Is the QRS interval normal?
Are the T waves normal?
Is the ST segment iso-electric?
How would you prepare a patient for ECG?
Expose as necessary
Select and prepare electrode site. Wipe if necessary
Small patches may need to be shaved if patient is hairy
Attach leads to electrodes
Apply electrodes to patient
What are some artefacts that can effect ECG readings?
Sweaty, moist skin
Oily, dirty or scaly skin
Excessive chest hair
Dry gel in electrodes
Patient movement or lead movement
Muscle tremor
Electrical interference
Low battery
Mobile phones
What is a characteristic of ST elevation?
Above iso-electric line
What is characteristic of ST depression?
Below iso-electric line
How would you apply a 12 lead ECG? (6)
V1 = 4th intercostal space right sternal border
V2 = 4th intercostal space left sternal border
V3 = between V2 and V4
V4 = 5th intercostal space between mid-clavicle left side
V5 = horizontally from V4 left anterior axilla
V6 = horizontally from V5 left mid axilla
