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Flashcards in Rhythms Deck (21):

ECG monitoring

Alcohol swab the area

shave dense hair or hair free areas

Place electrodes on bone rather than muscle

Red-Right arm
Green-leG-usually on abdomen left axillary region

Self-adhesive pads are used in emergencies, such as when a patient has collapsed. The cardiac rhythm can be assessed as soon as possible by applying defibrillator pads to the patient.

The self-adhesive pads can be used for monitoring rhythm and for hands-free shock delivery. They should be applied beneath the right clavicle and in the left mid-axillary line, overlying the V6 ECG electrode position. Alternatively anterior and posterior positions can be used.

If a patient requires monitoring, but is not so critically ill that defibrillator pads are likely to be needed, 3-lead monitoring can be used to observe their cardiac rhythm. This is the standard form of ECG monitoring employed by many cardiac monitors and defibrillators in general clinical use. Note that the electrodes are placed over the bony parts of the shoulders and usually over the pelvic crest, to minimise artefact from underlying muscle.

In some clinical settings, such as a cardiac care unit, 12-lead monitoring is available to enable early detection of ECG abnormalities that may develop in a limited number of leads. In particular this may help to identify some rhythm abnormalities. It is not always possible to identify an arrhythmia from a single lead ECG recording and occasionally the precise nature of the arrhythmia may be visible in only one of the 12 conventional ECG leads. In these cases 12-lead ECG monitoring may identify the cardiac rhythm accurately. Alternatively a 12-lead ECG can be recorded during an arrhythmia that has been detected by simpler forms of monitoring.

The heart is a three-dimensional organ and the 12-lead ECG addresses this by examining the heart’s electrical signals from 12 different directions.



1. Any electrical activity
2. QRS rate
3. Regular or irregular rhythm
4. QRS complex width normal or prolonged
5. Atrial activity present
6. Atrial and ventricular activity related


1. Any electrical activity

Check pulse and ensure not in asystole

Straight line-check monitoring equipmen

Atrial contractions but no ventricular=ventricular standstill- Cardiac pacing helps.

No pulse but random electrical activity=VF


2. QRS rate

1 large square=5mm
1 large square-0.2secs
1 large square=5 small squares
1 small square=0.04secs

300 divided by number of large squares


3. Regular or irregular rhythm

?AF-no p waves
?Atrial flutter-saw tooth pattern (II,III,aVF)
?ectopic beats
Broad complex ventricular beats=
1)supraventricular with BBB
2)ventricular-ectopic p wave shortly after QRS

?Atrial ectopic beats preceding ectopic p wave


4. QRS complex width normal or prolonged

4. QRS complex width normal or prolonged


Atrial activity

?AF-no p waves
?Atrial flutter-saw tooth pattern (II,III,aVF)
2:1 block


6. Atrial and ventricular activity related

3rd block-bradycardia


Arrest rhythms I

VT and VF (Shockable)

VF-if patient has a pulsef NOT VF
Can be similar to polymorphic VT and WPW syndrome

Torsades de pointes-type of VT-prolonged QT

SVT-broad complex tachycardia


Arrest rhythms II

PEA and asystole (Non-shockable)


(Atropine, Cardiac pacing, May need adrenaline/isoprenaline)

1st degree

Heart block: 1st degree AV block
Prolonged PR interval (0.12-0.2)
Can be in athletes, heart fibrosis, IHD

No need for treatment most times


Heart block 2nd degree:

Mobitz type 1
PR interval gradually increases and then QRS complex is missed.

May/may not need treatment


Mobitz type 2 AV block

Constant PR interval prolonged
Some p waves not followed by QRS complexes

Can be 2:1 and 3:1 block


Agonal rhythm

Dying patients and post unsuccessful resus attempts
Slow, irregular, wide complexes


Narrow complex tachycardia

AFib reg QRS complexes (many causes)
Aflut irreg QRS complexes (Chronic causes-COPD, PE, CCF)


Broad complex tachycardia

Ventricular Tachycardia


QT interval

Corrected 0.42secs

Shortened in hypercalcaemia with digoxin

Prolonged in Hypokalaemia, hypomag, hypothermia
Myocarditis and myocardial ischaemia



Immediate defib
If pulse is present then not in VF

The rhythm abnormality that is most likely to be mistaken for VF is polymorphic VT (Torsades de Pointes VT). Patients may be pulseless and lose consciousness during this rhythm; it may terminate spontaneously, or may degenerate into VF.

If this rhythm is present and the patient is in clinical cardiac arrest the appropriate treatment is defibrillation, so mistaking the rhythm for VF will not result in inappropriate treatment.

Pre-excited atrial fibrillation (AF) produces an irregular broad complex tachycardia that is sometimes mistaken for VT and could in theory be mistaken for VF.

If pre-excited AF causes adverse features without cardiac arrest, the correct treatment is synchronised cardioversion, so mistaking the rhythm for VT will not lead to inappropriate treatment. If pre-excited AF causes cardiac arrest and is mistaken for VF or pulseless VT, immediate defibrillation will be likely to correct the rhythm, although synchronised cardioversion would have been preferable.



VT may generate a detectable cardiac output (i.e. pulse) in some situations but in others may cause loss of cardiac output resulting in cardiac arrest. It may also degenerate into VF.

In VT the QRS morphology may be:

Monomorphic – a regular rhythm strip pattern
Polymorphic – the morphology of the QRS complexes varies from complex to complex – one form of polymorphic VT is Torsades de Pointes VT, in which there is a sinusoidal pattern of variation in QRS amplitude.

The importance of documenting and recognising these rhythms is to ensure that the patient receives immediate and appropriate specialist treatment to protect them from recurrence of this potentially dangerous arrhythmia and from sudden death as a result.



If the patient is pulseless and there is no electrical activity on the ECG, this is asystole.

The absence of any electrical activity indicates asystole in atria as well as ventricles. Occasionally ventricular asystole (sometimes called ventricular standstill) occurs in the presence of continued P wave activity in the atria. Atrial contraction alone will not maintain cardiac output, so cardiac arrest will be present, but patients with ventricular standstill and continued P wave activity may have a better chance of survival as cardiac pacing may restore ventricular contraction.

Sometimes during cardiac arrest it is not certain whether the ECG shows asystole or very fine VF. The best treatment in this situation is immediate high quality CPR. If the patient was in fine VF then good CPR may increase the amplitude and frequency of VF, making it easier to identify and more likely to respond to defibrillation. If the patient is in asystole, CPR is the appropriate treatment and the presence of asystole is likely to be recognised by its persistence.



PEA does not refer to a specific cardiac rhythm. It defines the clinical absence of cardiac output despite electrical activity that would normally be expected to produce a cardiac output.

It often has a poor prognosis, especially when caused by large acute myocardial infarction. Other treatable causes include:

Massive pulmonary embolism
Tension pneumothorax
Cardiac tamponade
Acute, severe blood loss