PR interval

Question 1

what are the three causes of a shortened PR interval

Answer 1

junctional rhythm (tachy; LGL; WPW

Question 2

what are the causes of a depressed PR segment

Answer 2

pericarditis, benign, atrial infarct

Question 3

what are additional signs besides a depressed PR segment that lead you to pericarditis as a dx

Answer 3

tachycardia, ST segment elevation, and notching of the QRS

Question 4

what are the characteristics of LGL syndrome

Answer 4

short PR interval, normal p wave, normal QRS, benign condition, can progress into tachycardias

the abnormal bundle is called a James Fiber

Question 5

what are the characteristics of WPW

Answer 5

short PR interval; slurring of the QRS- delta waves; can progress into tachycardias; normal p waves

the pathway is the Bundle of Kent

Question 6

what are the causes of prolonged PR interval >0.20 seconds

Answer 6

first degree AV block
2nd degree AV block- type 1 and type 2
3rd degree AV block
AV dissociation

Question 7

what are the characteristics of a first degree AV block

Answer 7

constantly prolonged PR interval- always the same duration; p wave present; p wave married to QRS; NO dropped beats; NSR

Question 8

what are the characteristics of 2nd degree AV block type 1 WENKEBACCCH

Answer 8

pr interval progressively elongates until finally it drops a beat; regularly irregular pattern with grouping could be 3:1, 4:1 etc

Question 9

what are the characteristics of 2nd degree AV block type 2

Answer 9

constant PR interval: could be long or normal
all of a sudden drops a beat at regular intervals
regularly irregular

very bad

Question 10

if you have a 2:1 AV block where every other beat is dropped, what should you assume it is

Answer 10

Mobitz type II

Question 11

what are the characteristics of a 3rd degree AV block

Answer 11

complete dissociation of the p wave and the QRS
ALWAYS more P waves than QRS complexes
then you define the ventricular rhythm as junctional or idioventricular escape rhythm

Question 12

AV dissociation is what

Answer 12

a broad term for p wave and QRS dissociation; the number of p waves and QRS are the SAME #

Question 13

true or false: wenkebach is a problem above the AV node

Answer 13

true

Question 14

T or F; type 2 is a problem below the AV node

Answer 14

true

Question 15

if you couldn’t distinguish a 2:1 block from type I or type II what could you do

Answer 15

vagal maneuvar

• vagal will increase the cycle of grouping in type i
• vagal will either eliminate the block or have no effect at all on type II

Question 16

what is a normal PR interval

Answer 16

0.12-0.20 seconds