ECG Pro

Question 1

What are you likely to see on an ECG in someone with atrial fibrillation? What causes this?

Answer 1

Chaotic atria - no p waves, ‘wavy baseline’

SA node inactive, chaotic atrial activity acting as pacemaker - no p waves, wavy baseline

Irregular pulse as AV node receiving/conducting random signals from atria

Question 2

What are 3 features on an ECG that can be seen during an MI?

Answer 2

1. ST-elevation (dying tissue, T wave may have inverted)
2. Pathological Q waves > 2mm deep
3. Inverted T waves

Question 3

What does the tombstone sign on an ECG indicate?

Answer 3

ST-elevation, MI

Question 4

Why would a T wave invert?

Answer 4

dead myocytes repolarize the wrong way

Question 5

What typically causes a R axis deviation? What does this mean?

Answer 5

R ventricular hypertrophy and pulmonary conditions

Depolarisation distorted tp R

Question 6

What usually causes a L axis deviation?

Answer 6

Conduction defects (not increased LV mass)

Question 7

What are the features of RBBB on an ECG? Which leads should you look at?

Answer 7

1. Bunny ears: V1, maybe V2 and 3
2. slurred S wave in lateral leads: 1, aVL and V6
3. QRS duration>120 ms

Question 8

What defines ST elevation?

Answer 8

S starts 2 small squares above isoelectric baseline in 2 consecutive chest leads

Question 9

What does a ‘tented’ T wave indicate?

When is it normal to see an inverted T wave?

Answer 9

Hyperkalemia (bigger repolarisation)

Inverted T wave can be normal in V1

Question 10

What is a common symptom of 2nd-degree heart block?

Answer 10

Syncope

Question 11

What is characteristic of Mobitz 1 Wenckebach?

Answer 11

The P-R interval gets continually longer until the AV node cannot conduct electricity QRS complex disappears.

“Wencke-wencke-wencke-bach (drop)”

Question 12

What is characteristic of Mobitz 2?

Answer 12

RANDOM blocked QRS (no PR prolongation); erratic relationship between P and R waves

Question 13

What causes heart block and what kind of heart rate is typically associated?

Answer 13

Problems with AV node: Bradycardia

Question 14

What is the definition of 2nd-degree heart block and what are the 2 types called?

Answer 14

Some P waves produce QRS: Mobitz 1: wenckebach Mobitz 2

Question 15

What causes atrial flutter and how does this appear on an ECG?What is one diagnostic criterion?

Answer 15

Single re-entry loop causing many atria contractions, “Sawtooth” of P waves (250-300 bpm)

Regularly irregular rhythm: AV node picks which P waves to conduct at regular intervals

Purkinje fibres normal: QRS complex narrow/normal

Question 16

Why can’t an AV node conduct every P wave?

Answer 16

Hit AV node during its refractory period

Question 17

How does a ventricular tachycardia appear on an ECG? What symptoms might the patient experience?

Answer 17

Abnormal depolarization/Beats originate in ventricular muscle >100 bpm

Shortens diastole -> SV reduces and heart fills less -> FOC reduces -> reduces CO

Wide QRS; Basically no AV node conduction, P waves, ABSENT PR interval

Question 18

What are some common causes of ventricular tachycardia?

Answer 18

Coronary disease, previous heart attacks, HF and heart valvular disease

Question 19

What causes ventricular fibrillation? How does this appear on an ECG and how would you treat it?

Answer 19

Abnormal firings of electrical signals -> STOPS beating

ECG is wavy chaotic baseline (no QRS or P waves) -> cardiac arrest
*require CRP, IV meds and defibrillation

Question 20

What does supraventricular tachycardia mean?

Answer 20

any tachycardia that is NOT ventricular

Question 21

What causes a bundle branch block?

Answer 21

Post MI dead myocardium, delayed conduction on affected side’s bundle of HIS

-> QRS on dead side is broad (electricity passes slower through myocardium)

Question 22

What defines a sinus bradycardia? When is this common?

Answer 22

SA node generates <60 bpm,

Everything else is normal
*Common in athletes and during sleep

Question 23

What defines sinus tachycardia? When is this normal?

Answer 23

SA node generates >100 bpm,

On ECG: may have shorter/steeper S wave, everything else normal exercise and anxiety

Question 24

What are some causes of R bundle branch blocks?

Answer 24

Congenital, MI, hypertension, PE

Question 25

What are 3 criteria on an ECG for a L bundle branch block?

Answer 25

1. QRS >120 ms
2. Downwardly deflected R wave in V1 (upwards in RBBB)
3. Absent Q wave in leads 1, V5 and V6

Question 26

How could you determine whether a L or R axis deviation is present with your thumbs????

Answer 26

L thumb - lead 1
R thumb - aVF

Normal: Both thumbs point up (R wave)

L axis deviation: Thumbs pointing away from each other, “Left is for leaving”

R axis deviation: thumbs point towards each other: “R is for reaching”

*Axis interminate if both thumbs point down

Question 27

What is the step by step process you would analyze an ECG? RRAP PRQQTT

Answer 27

Is there electrical activity?

Rate, rhythm, axis: leads 1 and aVF, p wave, PR segment (3-5 small squares), QRS: wide or narrow, QT (2.5 sm sqs), T wave

Question 28

What does the PR interval measure? How long should it be?

Answer 28

AV conduction time; 3-5 little squares

Question 29

What does the QT interval measure and how long should it be?

Answer 29

Ventricular activity, 2.5 small squares

Question 30

What does it mean if QRS is broad? >120 ms

Answer 30

Defect in HIS or purinke or myocyte-myocyte depolarisation

*Conduction through ventricular myocardium is very slow

Question 31

What does 1st and 3rd degree heart block mean?

Answer 31

1st: Av node conduction slower: prolonged PR interval but normal QRS
3rd: AV node lost ability to conduct electricity: no PR relationship, QRS broad because conduction through myocardium slower

Question 32

What symptoms might a patient with SVT experience?

Answer 32

CO is falling: hypotensive, dizziness, SOB, faintness, sweating