Ecgs 2

Front 1

What analogy do we use to explain conduction through the ventricles

Back 1

Driving:

Atria = suburbs

AV node = On-ramp

Ventricle = Highway

but if the conduction originates in the ventricles, it is like being in the veld, it is difficult to get onto the highway therefore cannot go at the same speed

Front 2

How does nervous stimuli affect the heart?

Back 2

Para-/sympathetic stimulus does not affect regularity but affects rate

Front 3

Is a sinus arrythmia normal?

Back 3

Yes, but it does not necessarily mean that the person is healthy

Front 4

Where does the impulse normally originate from?

Back 4

SA node

Front 5

What is normal with a SA nodal pacemaker?

Back 5

Sinus Rhythm

Sinus Arrythmia

Sinus Tachycardia

Sinus Bradycardia

Front 6

What are the characteristics of sinus rhythm?

Back 6

Normal rate, regular rhythm, narrow QRS

Front 7

What are the characteristics of sinus arrythmia?

Back 7

Cyclic rate variation with breathing

Front 8

When can you have an abnormal SA node pacemaker conduction

Back 8

1) Underlying systemic disease

2) SAN dysfunction such as: Sinus bradycardia, SAN exit block, SAN arrest (results in physiological pacemaker)

Front 9

What about when the impulse originates from the atria?

Back 9

This is abnormal. You can get:

1) Fast rhythm due to automaticity

2) Fast or slow rhythm due to reentry mechanism in atria

Front 10

When do you get a fast rhythm due to automaticity?

Back 10

Atrial tachycardia

Multifocal atrial tachycardia

Front 11

What are the characteristics of Atrial Tachycardia?

Back 11

Fast, Regular, narrow QRS, single abnormal P shape

Front 12

What are the characteristic of MAT?

Back 12

Fast, Irregular, narrow WRS, many abnormal P shapes

Front 13

What is a reentry mechanism?

Back 13

The cause of the arrhythmia is due to the electric signal not completing the normal circuit, but rather an alternative circuit looping back upon itself. It can be made of single or multiple circuits.

Analogy of the car splitting at the road block

Front 14

When do you get abnormal rhythm due to reentry mechanisms in the atria?

Back 14

Atrial Flutter

Atrial Fibrillation

Front 15

What are the characteristics of atrial flutter

Back 15

Fast, regular, narrow QRS, Sawtooth pattern and block (2:1, 3:1)

Hint 15

Single circuit

Front 16

What are the characteristics of atrial fibrillation?

Back 16

Variable rate, irregular, narrow QRS, no P, Squiggly baseline

Hint 16

Multiple Circuits

Front 17

What if the impulse originated from the AV junction?

Back 17

You get:

Fast rhythm due to reentry mechanism

Slower rhythm due to a physiological pacemaker

Front 18

There's that reentry thing again. Please explain it in this context, I didn't quite understand

Back 18

A prerequisite for re-entry is the presence oftwo pathways with differing conduction velocities that connect two points (in this case the atria with the ventricles) that are at the same point i.e. the AV node. The signal splits in two at arrival,but no arrhythmia is initiated as the slow signal becomes extinct when it meetsthe fast signal. However, after an extrasystole the fast pathway isstill refractory and conduction is by the slow pathway. The signal that reachesthe His by the slow pathway may find the fast pathway conducting and return tothe atria. This may set in motion a re-entry pathwaythrough the AV node resulting in AV nodal tachycardia.

Front 19

So when do you get a reentry mechanism happening at the AV node?

Back 19

AV nodal reentry tachycardia

AV reentry tacahycardia

Front 20

What is AVNRT and what are it's characteristics?

Back 20

Born with extra excitatory tissue, treated with vagal maneuver (increase intraabdo pressure to stimulate vagus nerve). This is a circuit within AV node

Very fast, regular, narrow QRS, shorter PR (P often embedded in QRS complex) ( P may be seen retrograde in II, III, aVF)

Hint 20

1st = AVNRT

Front 21

What is AVRT and what are it's characteristics?

Back 21

Underlying disease: Wolf-Parkinson-White. This circuit does not necessarily have to be completed within AV node.

Fast, regular, narrow or wide, short PR,

Hint 21

2nd = AVRT

Front 22

When do you get a slower rhythm due to physiological pacemaker?

Back 22

Junctional Rhythm

Front 23

What are the characteristics of a Junctional Rhythm?

Back 23

Slow, Regular, Narrow QRS, noP/neg P/P after

Front 24

If the impulse originates from the ventricle is it abnormal and what type do you get?

Back 24

Yes, it is.

Fast rhythm due to ventricular focus firing

Slower rhythm due to back-up pacemaker

Front 25

Give examples of a fast rhythm generated by ventricular focus firing

Back 25

Monomorophic ventricular tachycardia

Polymorphic ventricular tachycardia

Front 26

What is monomorphic ventricular tachycardia? What are its characteristics?

Back 26

Stimulus originates from single point in ventricles.

Fast, regular, Wide QRS, no P

Front 27

What is polymorphic ventricular tachycardia?

Back 27

Stimulus originates from multiple points in ventricles

Front 28

What are the types of P-VT that you can get?

Back 28

Torsades de pointes

V fib

Front 29

Describe Torsades de pointes

Back 29

Commonly caused by MI.

Has characteristic "twisting" morphology.

Fast, irregular, wide mixed QRS (Prolonged QT)

Front 30

Describe V Fib

Back 30

Rapid, irregular activity in the ventricles

Fast, irregular, no P waves QRS complexes or T waves.

Front 31

When do you get a slow rhythm due to a backup pacemaker?

Back 31

Idioventricular rhythm

Front 32

Tell me about the characteristics of an idioventricular rhythm

Back 32

Usually associated with other disease such as Sinus Arrest

Slow, regular, wide QRS, no P linked to QRS

Hint 32

NB It is also called a ventricular escape rhythm

Front 33

What are the abnormal impulses that may be superimposed on a rhythm strip?

Back 33

Premature atrial complexes

Premature junctional complexes

Premature ventricular complexes

Front 34

Describe PAC

Back 34

Early P, normal QRS wave

Front 35

Describe PJC

Back 35

no P, early normal QRS wave

Front 36

Desrcibe PVC

Back 36

no P, early wide QRS

Front 37

What are the differences between premature complexes and physiological pacemakers?

Back 37

Premature complexes:

Superimposed on underlying rhythm, wave is premature, an electrical abnormality

Physiological pacemaker:

Primary pacemaker too slow/stopped, wave arises after prolonged pause, electrical safety backup

Front 38

What are the different ways that impulses can be conducted through the atria?

Back 38

Normal sinus rhythm

1st degree block

2nd degree Type I block

Other: Pericarditis

Front 39

Outline impulse conduction in sinus rhythm

Back 39

Normal P-R interval 120-200ms

regular, narrow QRS

Front 40

What is a first degree block and what are its characteristics?

Back 40

A prolongation of PR interval >200ms, it a sign of slowed impulse conduction through atria. It does not give bradycardia

slower,Fixed PR >200ms, regular, narrow QRS

Front 41

What is a second degree Type I block?

Back 41

Progressive prolongation of the PR interval culminating in a non-conducted P wave i.e. a dropped beat, only one QRS complex is dropped

Cycles of progressively increased PR with last QRS dropped: irregular/group beating, narrow QRS

Front 42

What is pericarditis and how does it present on ECG?

Back 42

Inflammation of the pericardium produces characteristic chest pain (retrosternal, pleuritic, worse on lying flat, relieved by sitting forward), tachycardia and dyspnoea.

PR interval depressed, elevated ST segment

Front 43

What are the different presentations of impulse conduction through the AV junction?

Back 43

Normal (represents vagal tone)

2nd degree Type II block

3rd degree Block

Front 44

What is a 2nd degree type II block and how does it present on ECG?

Back 44

Intermittent non-conducted P waves without progressive prolongation of the PR interval. Usually due to infarction, ischaemia, necrosis

RR interval surrounding the dropped beat(s) is an exact multiple of the preceding RR interval

No warning signs before dropped beat

fast/slow, normal PR, dropped QRSs, group/irregu;ar, narrow/wide

Front 45

What is a 3rd degree block and how does it present on ECG?

Back 45

Complete blockage of AV node, ventricular pacemaker takes over

Slow, regular, QRS wider than N, no relationship with P

Front 46

Tell me about impulse conduction through Ventricles

Back 46

Normal is fast: QRS<120ms, narrow

Delayed < 120 ms

Front 47

When can conduction through ventricles be delayed?

Back 47

Conduction pathways (Bundle of His, Bundle branches, Fascicles): LBBB, RBBB, Hemiblocks (i.e. fasicular blocks)

Muscle:

Infarcts, electrolyte abnormalities, drug toxicity, diseases (e.g. pericarditis or hypertrophy)

Can cause wide QRS, ST elevated/depressed, prolonged QT, T waves abnormal size and polarity

Front 48

What can we learn from the width of the QRS?

Back 48

Narrow = origin is above AV junctione.g. sinus tachy/brady, Afl, Afib

Wide = a) impulse origin above AV junction

b) origin is above AV junction (supraventricular pacemaker) but conduction is slowed past AV e.g. VT vs SVT + LBBB, vent pacemaker vs sinus brady + LBBB

Front 49

What analogy do we use to explain Blocks?

Back 49

Relationships:

Normal = 2 people in close relationship

1st degree = Marriage, but are distant

2nd degree Type I = Close but drift apart until one night stand

2nd degree Type II = Unexpected one night stand but still close. The more unexpected one night stands, the more likely to stop working.

3rd degree: Divorced but sometimes meet at elevator