ECG - Identifying some Basic Disturbances of Rhythm Flashcards

Question 1

Q

Diagnose

Question 2

Q

IMPORTANT:What is the duration of the PR interval?

Question 3

Q

Name a disease with an irregular irregular rythem?

Answer

A

An irregularly irregular rhythm has no pattern at all. All of the intervals are haphazard and do not repeat, with an occasional, accidental exception. Luckily, there are only three irregularly irregular rhythms: atrial fibrillation, wandering atrial pacemaker, and multifocal atrial tachycardia.

Question 4

Q

Diagnose

Question 5

Q

Diagnose

Question 6

Q

List the 12 steps for analysing a ECG?

Question 7

Q

Question 8

Q

What does SVT, AVNRT and AVRT stand for?

Answer

A

Supraventricular tachycardia (supra=above)

atrioventricular nodal reentrant tachycardia (reentrant=(going round and round) pointing inwards.)

Atrioventricular reentrant tachycardia

Question 9

Q

Answer

A

P-R interval- P to the start of the QRS wave

Question 10

Q

What is the difference between first degree and second degree AV nodal block?

Answer

A

In 1st degree AV nodal block, the PR interval is prolonged but every beat from the atria reaches the ventricles

In 2nd degree AV nodal block, some of the beats from the atria DO NOT get conducted to the ventricles

Question 11

Q

Diagnose

LOOK AT LAZ NOTES

Answer

A

Mobitz Type 1 (Wenckebach)

Mobitz Type 1 = gradual prolongation of the PR interval culminating in a dropped beat

The PR interval gradually becomes longer, in Mobitz Type 1, until the AV node can no longer cope and then blocks the conduction completely leading to a missed QRS complex

Question 12

Q

Answer

A

SVT

HAS NO P WAVE

Question 13

Q

Bundle Branch Blocks

Depolarisation of the ………….. ………….. and the ………….. ………….. are seen as the QRS complex on the ECG

Therefore, a conduction block of the ………….. …………..would be reflected as a change in the QRS complex

If there is a block in the right bundle branch, you get conduction going down one of the bundle branches and then spreading slowly across the myocardium

With a right bundle branch block, the left side would depolarise normally but the right side depolarises ………….. as the depolarisation has to spread slowly form the left side to the right side

With bundle branch blocks you will see TWO ECG CHANGES:

QRS complex ………….. (>0.12s)

QRS ………….. ………….. (varies depending on the ECG lead, and if it is right or left bundle branch block)

You would look at the chest leads to identify this

The QRS complex is time taken for all ………….. ………….. to be depolarised

So if one bundle branch is blocked, the depolarisation comes down and slowly depolarises across the ventricular myocardium so the time taken for all ventricular myocytes to depolarise is greatly ………….. giving a wide QRS complex

Answer

A

Bundle Branch Blocks

Depolarisation of the bundle branches and the purkinje fibres are seen as the QRS complex on the ECG

Therefore, a conduction block of the Bundle Branches would be reflected as a change in the QRS complex

If there is a block in the right bundle branch, you get conduction going down one of the bundle branches and then spreading slowly across the myocardium

With a right bundle branch block, the left side would depolarise normally but the right side depolarises slowly as the depolarisation has to spread slowly form the left side to the right side

With bundle branch blocks you will see TWO ECG CHANGES:

QRS complex widens (>0.12s)

QRS morphology changes (varies depending on the ECG lead, and if it is right or left bundle branch block)

You would look at the chest leads to identify this

The QRS complex is time taken for all ventricular myocytes to be depolarised

So if one bundle branch is blocked, the depolarisation comes down and slowly depolarises across the ventricular myocardium so the time taken for all ventricular myocytes to depolarise is greatly increased giving a wide QRS complex

Question 14

Q

Question 15

Q

Atrial Fibrilation

P waves ………….; oscillating baseline f (fibrillation) waves

Atrial rate 350600 beats/min
Irregular ………….. rhythm
Ventricular rate 100180 beats/min

Answer

A

Atrial Fibrilation

P waves absent; oscillating baseline f (fibrillation) waves

Atrial rate 350600 beats/min
Irregular ventricular rhythm
Ventricular rate 100180 beats/min

Question 16

Q

Sinus Tachycardia

P waves have ………….. morphology
Atrial rate 100200 beats/min
……………. ventricular rhythm
Ventricular rate 100200 beats/min
One P wave ……………… every QRS complex
Often ………………… response

–Hypovolaemia, sepsis, stress, etc.

Answer

A

P waves have normal morphology
Atrial rate 100200 beats/min
Regular ventricular rhythm
Ventricular rate 100200 beats/min
One P wave precedes every QRS complex
Often physiological response

–Hypovolaemia, sepsis, stress, etc.

Question 17

Q

Bundle Branch Block

Why does the QRS complex widen?

Question 18

Q

State the Normal ECG values for the following?

Question 19

Q

Diagnose

Answer

A

1st degree AV block

1 to 1 relationship

long PR interval

Question 20

Q

What QRS morphology is characteristic for RBBB?

Question 21

Q

Diagnose

Question 22

Q

Question 23

Q

What is sinus Tachycardia?

Answer

A

Sinus tachycardia (also colloquially known as sinus tach or sinus tachy) is a sinus rhythm with an elevated rate of impulses, defined as a rate greater than 100 beats/min (bpm) in an average adult.

Question 24

Q

IMPORTANT: What is the duration and amplitude of the QRS complex?

State what it is in V6 as well?

And the normal range for the QRS axis?

Question 25

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Diagnose

Question 26

Q

Normal Impulse Conduction

Question 27

Q

Question 28

Q

What is the duration and aplitude of the P wave?

Question 29

Q

What QRS morphology is characteristic for LBBB?

Question 30

Q

How do you calculate the heart rate in an ECG?

Answer

A

Count the interval between the RR interval?

do 300/ the number of large squares. between the RR interval

Although fast, this method only works for regular rhythms and at a paper speed of 25mm/sec.

Question 31

Q

Diagnose

Question 32

Q

What is the delta wave?

Answer

A

The Delta wave is a slurred upstroke in the QRS complex often associated with a short PR interval. It is most commonly associated with pre-excitation syndrome such as WPW.

Question 33

Q

Preexcitation Syndrome

Normally, the atria and the ventricles are electrically isolated, and electrical contact between them exists only at the “atrioventricular node”. In all pre-excitation syndromes, at least one more conductive pathway is present. Physiologically, the normal electrical depolarization wave is delayed at the atrioventricular node to allow the atria to contract before the ventricles. However, there is no such delay in the abnormal pathway, so the electrical stimulus passes to the ventricle by this tract faster than via normal atrioventricular/bundle of His system, and the ventricles are depolarized (excited) before (pre-) normal conduction system. This creates the ventricular pacemaker type of ectopic pacemaker.

Answer

A

Preexcitation Syndrome

Accessory pathway (connect atrium to ventricle)
Short PR interval
Ventricular pre-excitation
Predisposes to accessory pathway tachycardias (AVRT)
Accessory pathways:

–1/3 can conduct antegradely (WPW)

–2/3 can only conduct retrogradely (concealed pathways)

•Ablation of accessory pathway

Question 34

Q

Diagnose

Question 35

Q

Diagnose

Question 36

Q

AV nodal reentrant tachycardia (AVNRT)

Are the QRS complexes regular?

Where are the p waves?

What causes it?

What is it responsive to?

Answer

A

AV nodal reentrant tachycardia (AVNRT)

Narrow-complex tachycardia
Regular QRS complexes
P waves often buried within QRS or just after QRS
Re-entrant circuit within AV node
Adenosine responsive

Question 37

Q

Diagnose

Answer

A

3rd degree AV nodal Block

NONE OF THE P WAVES RELATED TO THE QRS. THE RATES OF P WAVES AND QRS COMPLEX ARE NOT THE SAME

AV node is not functioning so there is no conduction from the atria to the ventricles

The ventricles start firing on their own as an escape mechanism

The P waves and the QRS complexes are COMPLETELY DISSOCIATED

The P waves and QRS complexes may occur at regular intervals but they are firing independently of each other

AV dissociation on the ECG = Complete Heart Block

You need to look at the P and QRS relationship to be able to identify this

Question 38

Q

With Bundle Branch Blocks you will see two ECG changes:

Name this?

Question 39

Q

IMPORTANT: What is the normal duration for the QT interval?

Question 40

Q

Draw a diagram showing how AV nodal reentrant tachycardia (AVNRT) occurs?

Answer

A

Causes synchronised artia and ventricular contraction

Single sent to the atria the same time it is sent to the ventricle

Question 41

Q

How do you distinguish between Right Bundle Branch Block and Left Bundle Branch Block?

Answer

A

In RBBB, the wide QRS complex assumes a unique, virtually diagnostic shape in the leads overlying the right ventricle (V1 and V2)

Remember it as WiLLiaM MaRRoW

LBBB:

V1 = W

V6 = M

RBBB:

V1 = M

V2 = W

For LBBB, the wide QRS complex assumes a characteristic change in shape in those leads opposite the left ventricle (right ventricular leads - V1 and V2)