ECG-PA

Question 1

The diagnostic criteria for LBBB are:

Answer 1

*Broad QRS complex: >120 ms (3 small squares)
*Dominant S wave in V1
*Broad, monophasic R wave in lateral leads: I, aVL, V5-V6
*Absence of Q waves in lateral leads
*Prolonged R wave >60ms in leads V5-V6

Question 2

The diagnostic criteria for RBBB are

Answer 2

*Broad QRS complex: >120 ms (3 small squares)
*RSR’ pattern in V1-V3: an initial small upward deflection (R wave), a larger downward deflection (S wave), then another large upward deflection (a second R wave, which is indicated as R’)
*Wide, slurred S wave in lateral leads: I, aVL, V5-V6

Question 3

Normal PR interval is ?

Answer 3

<200 ms or 5 small squares or 1 large square.

Question 4

First degree Heart block

Answer 4

Prolongation of the PR interval ( PR >200 ms)

Question 5

Causes of first degree HB ?

Answer 5

It may be a
sign of coronary artery disease, acute rheumatic carditis, digoxin
toxicity or electrolyte disturbances.

Question 6

Definition of second degree HB?

Answer 6

It is defined as intermittent failure of conduction to the bundle of Hiss through the AV node.

Question 7

Types of second degree HB?

Answer 7

*Wenckebach’ or ‘Mobitz type 1
*Mobitz type 2
* 2:1, 3:1, 4:1 block

Question 8

Definition of Wenckebach’ or ‘Mobitz type 1 second degree heart block ?

Answer 8

*Progressive lengthening of the PR interval
*One nonconducted P wave
* Next conducted beat has a shorter PR interval than the
preceding conducted beat
* As with any other rhythm, a P wave may only show itself as a
distortion of a T wave

Question 9

Mobitz type 2 second degree HB?

Answer 9

*PR interval of the conducted beats is constant
* One P wave is not followed by a QRS complex

Question 10

Type 3 second degree HB ?

Answer 10

• Two P waves per QRS complex
• Normal, and constant, PR interval in the conducted beats

Question 11

In complete Heart Block, if the rhythm strip is not available?

Answer 11

carefully look for consistency or inconsistency of PR intervals in all the leads. AV dissociation.

Question 12

Normal QRS duration ?

Answer 12

< 120 ms

Question 13

RBBB patterns with a QRS complex of
normal duration are____

Answer 13

Quite common in normal people

Question 14

Left bundle branch block (LBBB) is always an indication of heart
disease, usually of the _______

Answer 14

Left ventricle

Question 15

partial right bundle branch block

Answer 15

An R’sR pattern with a normal QRS duration is called partial RBBB

Question 16

LBBB is associated with T wave ____ in the lateral leads (I, VL
and V5–V6), though not necessarily in all of these.

Answer 16

inverison

Question 17

In left anterior fasicular block (left hemiblock) , the cardiac axis will ?

Answer 17

Rotate upward (left axis deviation)

Question 18

In left posterior fasicular/ hemiblock the ECG axis ?

Answer 18

rightward

Question 19

In RBBB

Answer 19

the axis is normal because the depolarization vector is towards the left apex.

Question 20

Bifasicular block?

Answer 20

It occurs when there is dysfunction of RBB + left anterior fascicle. The axis will be leftward.

Question 21

Clinical thinking in first degree block ?

Answer 21

• Often seen in normal people.
• Think about acute myocardial infarction and
  acute rheumatic fever as possible causes.
• No specific action needed.

Question 22

ECG in LAFB

Answer 22

*rS complexes in leads II, III, aVF, with small R waves and deep S waves
*qR complexes in leads I, aVL, with small Q waves and tall R waves
*Left Axis Deviation (LAD): Leads II, III and aVF are NEGATIVE; Leads I and aVL are POSITIVE
Associated features:
*QRS duration normal or slightly prolonged (80-110ms)
*Increased QRS voltage in limb leads