Chapter 8 Rhythm recognition

Question 1

Where do the place the colour-coded 3 lead ECG electodes on the patient: White, Black, Red

Answer 1

WHITE for right (right shoulder)
SMOKE OVER FIRE (black left shoulder, red left lower chest)
Place on clean dry skin (can use alcohol wipes, shave hair). Place over bone. Muscle gives artefact

Question 2

When would you choose to use antero-posterior placement for defibillator pads?

Answer 2

Permanent pacemaker in right precordial chest position
Transcutaneous pacing (reducing thoracic muscle activity)
Chest trauma
Refractory VT/VF

Question 3

What is the difference between asystole and ventricular standstill?

Answer 3

Asytole - flat (often undulating flat line). Implies ventricular AND atrial asystole

Ventricular standstill: ongoing atrial activity - p waves, atrial flutter or fibrillation but NO ventricular activity. Can try pacing this patient

Question 4

On a telemetry strip, how can you accurately count the rate for a very fast or irregular rhythm?

Answer 4

Count number of QRS complex in 6 seconds ( 30 large sqaures) and x by 10

Question 5

What are the three rhythms that a cardiac arrest can be classified into?

Answer 5

1) Shockable: VT, VF
2) Asystole
3) PEA

Question 6

Atrial fibrillation passed down an accessory pathway may produce a very fast tachyarrhythmia that may be mistaken for?

Answer 6

Polymorphic VT. Rhythm is fast, up to 300 BPM, broad and irregular.
Would not be inappropriate to shock if the patient was not well perfused.

Question 7

VT may be classified morphologically into two types. What are they?

Answer 7

Monomorphic

Polymorphic

Question 8

What is a capture beat? What is a fusion beat?

Answer 8

Capture: normal atrial beat is captured during VT. Normal QRS complex amongst VT seen
Fusion: Fusion of normal beat with VT beat

Question 9

What would an atrial tachycardia with bundle branch block appear like on an ECG?

Answer 9

As a broad-complex tachyarrhythmia

Question 10

Are polymorphic and torsades de pointe the same?

Answer 10

No, torsade is a type of polymorphic VT (axis of electrical activity changes in a rotational way)

Question 11

A patient has torsades de pointes. Why would you avoid amiodarone when it is normally used in VT?

Answer 11

This is a specific type of polymorphic VT that is often due to a prolonged QT interval. Amiodarone will worsen the prolongation.

Question 12

How to you prevent a recurrence of torsade de pointes

Answer 12

Replace potassium
Replace magnesium
Increasing HR by overdrive pacing is HR is slow
Cease and withold any QT prolonging drugs (including amiodarone)

Question 13

You’re not sure if the rhythm is asystole or very fine VF, should you shock?

Answer 13

No, give CPR. This my increase amplitude and increase success of shock

Question 14

What are your treatment options for a bradyarrhythmia?

Answer 14

1 ) atropine 500mcg bolus (repeat up to 3mg)
2) Isoprenaline 1-10mcg/min or
Adrenaline 1- 10mcg/min ( or 0.1-1.0mcg/kg/min)
3) Transcutaneous pacing

Question 15

Is 2nd degree heart block, Mobits type 1 (Wencklebach) always pathlogical? Does it need urgent treatment

Answer 15

Can be normal in highly trained athletes with high vagal tone, outside of this, is usually pathological. Due to ischaemic, medications (beta blockers, Ca blockers, digoxin, amiodarone), myocarditis, following cardiac surgery.
If asymptomatic does not require urgent treatment.

Question 16

Is the dropped QRS in 2nd degree HB mobits type 2 alway at a regular interval?

Answer 16

No, can be regular but dropped beat can be random, giving an irregular HR.

Question 17

A patient is described as having an AV block as 2:1 or 3:1. Which rhythms could the patient be in?

Answer 17

Either mobits type 1 or 2 can be described this way.
2:1 implied 2 p waves to 1 QRS. Given the difficulty seeing PR prolongation, it’s hard to tell which rhythm the patient is in.

Question 17

A patient is described as having an AV block as 2:1 or 3:1. Which rhythms could the patient be in?

Answer 17

Either mobits type 1 or 2 can be described this way.
2:1 implied 2 p waves to 1 QRS. Given the difficulty seeing PR prolongation, it’s hard to tell which rhythm the patient is in.

Question 18

A patient is in complete heart block HR 40 but they seem to be well perfused. Is this a stable rhythm?

Answer 18

No, risk of abruptly deteriorating into asystole

Question 19

What is the difference between an idioventricular rhythm and an accelerated idioventricular rhythm

Answer 19

Idioventricular rhythm is arising from the ventricular myocardium, HR 30 -40.
Accelerated means the rhythm is still from ventricular myocardium but with a normal HR, but not fast enought to be VT, usually 50 - 110

Often seen as a reperfusion rhythm post lysis/PCI

Question 20

How dangerous is an accelerated idioventricular rhythm?

Answer 20

Often seen as a reperfusion rhythm post lysis/PCI.

Usually not a serious risk unless there is haemodynamic compromise or its develops into VT/VF, which is uncommon

Question 21

How do you distinguish from an accelerated idioventricular rhythm an a junctional rhythm?

Answer 21

Both may have the same HR (50 to 110) however idioventricular will have wide QRS, junctional will be narrow (unless there is a bundle branch block)

Question 22

What is an agonal rhythm?

Answer 22

Seen in dying patients Slow irregular, wide ventricular complexes of varying morphology.
Usually does not generate a pulse.
Complexes slow and broaden and deteriorate into asystole.

Question 23

Is atrial flutter always regular?

Answer 23

No, can have variable conduction, producing an irregular rhythm

Question 24

In atrial flutter, why is a HR or 150 called 2:1 or 3:1 or 4:1?

Answer 24

Because the flutter waves always seem to occur with a rate of 300 bpm.
So if ventricular HR is 150, conduction is 2:1

Question 25

Where does AF usually originate from on the heart?

Answer 25

The right ventricle. So is a recognised complication of disases affecting the right heart including COPD, major PE, complex congenital heart disease, CCF

Question 26

Does the rate of VT increase or decrease the risk associate with this rhythm?

Answer 26

Faster VT > 200 BPM is more likely to deteriorate into VF

Question 27

The Q wave can be difficult to measure due to difficulty detecting the end of the T wave. What is generally the best lead to measure it in?

Answer 27

Lead II
Also lead 1 and V5
Can average over several leads

Question 28

What happens to the QT interval as the HR increases?

Answer 28

QT interval shortens

Question 29

When is a QT prolonged?

Answer 29

Men > 430
Female > 450
If > 500 high risk of cardiac arrest and death

Question 30

What is the risk with long or short QT or brugada syndrome?

Answer 30

Risk of ventricular arrhythmia and death

Question 31

What would a 2nd degree HB mobites type II look like?

Answer 31

3 p-waves of regular intervals to every 1 QRS complex