ECG Flashcards
6 chest electrodes in a 12-lead ECG
V1-V6
Red, yellow, green, brown, black, purple
4 limb electrodes in a 12-lead ECG
RA, LA, LL, RL
Red, yellow, green, black
Location of limb electrodes on 12-lead ECG
- Ulnar styloid process (wrist)
- Medial or lateral malleolus (ankle)
3-Lead electrode placement
RA, LA, LL
Red, yellow, green
5-Lead ECG electrode placement
RA, LA, LL, V, RL
Red, yellow, green, white, black
What is the importance of ECG paper?
- Easy measurement of cardiac timing intervals - any timing irregularities can be seen.
- Can work out heart rate just by looking at the ECG trace.
What causes supraventricular tachycardia (SVT)?
Increased rate of depolarisation
What are the two shockable rhythms?
Pulseless ventricular tachycardia (pVT) and ventricular fibrillation (VF)
What happens during the PR interval?
Electrical impulse spreads over atrium, through AV node and Bundle of His
What happens during the ST segment?
Isoelectric point - no change in electrical activity
What happens during the QT interval?
Depolarisation and repolarisation of the ventricles
What happens during the P wave?
- Spread of electrical impulse across atria from SA node
- Atrial depolarisation
What happens during the QRS complex?
- Spread of electrical impulse through the ventricles
- Ventricular depolarisation
What happens during the T wave?
Ventricular repolarisation
What causes sinus tachycardia?
Increased rate of depolarisation in the SA node
What is the pattern of the PQRST complex in sinus tachycardia?
Normal
What is the pattern of the PQRST complex in ventricular tachycardia?
Absent P waves and a wide QRS complex
(Very plain up and down)
What causes supraventricular tachycardia?
Increased rate of depolarisation
How is supraventricular tachycardia characterised on ECG?
Absent or abnormal P waves
What causes atrial fibrillation?
Electrical impulses fire off from different places in the atria, in a disorganised way
How is atrial fibrillation characterised on ECG?
Irregular rhythm with no P waves
What causes ventricular fibrillation?
The ventricles suddenly attempt to contract at rates of up to 500bpm
Which arrhythmia shows the heart is no longer an effective pump and advanced life support is needed?
Ventricular fibrillation
How is ventricular fibrillation characterised on ECG?
Chaotic irregular deflections of varying amplitude with no identifiable P waves, QRS complexes, or T waves
What is pulseless electrical activity?
Electrical activity of heart appears normal on ECG BUT it is not accompanied by the mechanical function of the heart, and no pulse is present
What are the 6 T’s?
- Thrombosis (pulmonary or coronary)
- Tension pneumothorax
- Cardiac tamponade
- Toxins (e.g. drug overdose)
- Tachycardia
- Trauma
What are the 6 H’s?
- Hypovolaemia
- Hyper/Hypokalaemia
- Hypoxia
- Hydrogen ions (Acidosis)
- Hypothermia
- Hypoglycaemia
The 6 H’s and T’s are potential causes of which arrhythmias?
Pulseless electrical activity and asystole
What is the treatment for PEA and asystole?
- Emergency CPR
- Urgent adrenaline administration
- Treat the underlying cause (6H’s and 6T’s)
