Rhythm Recognition Flashcards
What are the sites for defib pads
beneath the right clavicle
left mid-axillary line
What is the difference in voltage in myocardial cells and extracellular space?
90mV
What triggers depolarisation and contraction?
Ion shift
In normal sinus rhythm where does depolarisation begin?
the pacemaker cells (SA node)
What is the first wave in the ECG?
P wave
What does the P wave represent?
depolarisation spreading from the SA node through the atrial myocardium
What happens after the P wave
slow conduction through the AV node, followed by rapid conduction to the ventricular myocardium
What conducts through the ventricular myocardium?
Purkinje fibres
What carries Purkinje fibres?
Bundle of His
What does the QRS complex represent?
depolarisation of the ventricular myocardium
What does the segment between the P and QRS complex represent?
Isoelectric segment- delay in transmission in the AV node
What does the T wave represent?
recovery of the resting potential in the cells of the conducting system and ventricular myocardium
What is happening in bundle branch block?
One of the segments of the bundle of His is diseased or damaged and so conduction is carried much more rapidly through the other division and then more slowly through the ventricular myocardium
What happens to the QRS in bundle branch block?
broadened- because depolarisation of both ventricles takes longer
What is the 6 stage system to analyse an ECG?
- Is there electrical activity
- What is the QRS rate
- Is the QRS rhythm irregular/regular
- Is the QRS complex width normal?
- is atrial activity present
- is atrial activity related to ventricular activity
What is happening in VF?
All coordination of electrical activity is lost
- no effective ventricular contraction and no detectable cardiac output
What is PEA
There are complexes on the ECG that would be expected to produce a pulse but there isn’t one
What is a normal ventricular rate?
60-100
What represents one second on an ECG?
If calibrated to 25mms
5 large squares
How should you estimate ventricular rate?
Count the cardiac cycles in 30 large squares (6 seconds) and multiply it by 10
If the rhythm is irregular what needs to be decided?
- is it totally irregular
- is the basic rhythm regular with intermittent irregularity
- is there a recurring cyclical variation in the R-R intervals?
If the QRS complex of an ectopic is narrow where has it likely originated from?
The atria
What might broad complex ectopics represent?
Ventricular origin or ectopics with BBB
What is a premature beat?
Ectopic beats that occur early