Arrhythmias Part 3

Question 1

Describe Wenckebach/Mobitz Type 1

Answer 1

Longer, longer, longer, Drop, now you have wenckebach.

Question 2

Describe Mobitz Type II.

Answer 2

• A P wave either appears or doesn’t.
• If it does appear, it is consistent in its timing.

Question 3

Describe 3rd degree AV Block

Complete AV Block/Heart Block

Answer 3

• More P waves than QRS complexes.
• No apparent connection between P waves and QRS complexes
• R-R and P-P timings are consistent

Ventricular rate is more likely to be present, 20-40BPM.

P and Qs don’t agree, now you have a 3rd degree.

Question 4

What is characteristic of 1st degree AV Block?

Answer 4

• P wave with every QRS
• PR interval > 0.2s

Interval is from the beginning of the P wave to the start of the QRS.

Question 5

What is characteristic of 2nd degree AV Block?

Answer 5

• Unequal P:QRS
• Some conduction gets through, some doesn’t

Includes Mobitz Type 1 and 2

Question 6

How does a RBBB present?

Answer 6

• QRS > 120ms
• RSR’ in V1-3 (M pattern)
• Wide, slurred S wave in lateral leads

WiLLiaM MaRRoW

M = V1
RR = Right BBB
W = V6

Question 7

How does a LBBB present?

Answer 7

• QRS >= 120ms
• Dominant S wave in V1
• Broad, monophasic R wave in lateral leads
• Absence of Q waves in lateral leads
• Prolonged R wave peak time > 60ms in V5-6

WiLLiaM MaRRoW

W = V1
LL = LBBB
M = V6

Question 8

RBBB vs LBBB image

Answer 8

Question 9

What are the criteria for a left anterior fasicular block?

Answer 9

• Left axis deviation
• Small Q waves in Leads 1, aVL, and tall R waves
• Small R waves in leads II, III, aVF, and deep S waves
• QRS < .12ms

She said just remember the left axis deviation

LAFB presents as left axis deviation that is not better explained by LVH.

Question 10

What are the criteria for a left posterior fasicular block?

Answer 10

• Right axis deviation
• Small R waves in Leads I, aVL, and deep S waves
• Small Q waves in leads II, III, aVF, and deep R waves
• QRS < .12ms

She said just remember the right axis deviation

Usually presents combined with RBBB to create a bifascicular block
Make sure to r/o other causes of right axis deviation

Question 11

What is a bifascicular block?

Answer 11

RBBB + LPFB or LAFB

Question 12

What are underachieving blocks?

Answer 12

• QRS wider than 0.1ms with no other criteria.
• Incomplete BBB with a QRS that is not wider than 0.12ms

Question 13

What are the two preexcitation syndromes and what is their common characteristic?

Answer 13

• WPW syndrome
• LGL syndrome
• Short PR interval < 0.12s

WPW = wolff-parkinson-white
LGL = Lown-Ganong-Levine

Question 14

What is the special wave in WPW syndrome and the name of the accessory pathway associated?

Answer 14

• Delta wave (slurred initial upstroke)
• Accessory pathway: Bundle of Kent

QRS widened beyond 0.1s due to abnormal depolarization.

Question 15

Delta Wave Image

It is so tiny

Answer 15

Question 16

What are the characteristics of LGL and the associated accessory pathway?

Answer 16

• PR interval shortened to < 0.12s
• QRS complex NOT widened.
• No delta wave
• Accessory pathway: James Fibers

Question 17

What can the preexcitation syndromes lead to?

Answer 17

SVT

Question 18

What are orthodromic tachycardia and antidromic tachycardia?

Answer 18

• Orthodromic: Occurs through the AV node and narrow QRS complexes occur.
• Antidromic: Occurs through accessory pathways and wide QRS complexes occur.

Antidromic = Accessory

Question 19

What happens to conduction in hypothermia? What is the weird STE seen?

Answer 19

• Slowing of everything.
• J-wave/Osborn wave

Question 20

What are the effects of digoxin/digitalis on an EKG?

Answer 20

• ST depression with flattening or inversion of the T wave
• Depressed ST segments have gradual downslopes and are asymmetric

Question 21

What is considered an abnormal QTc?

Answer 21

> 500ms