Intracardiac Intervals

Question 1

What is the normal PA interval Range

Answer 1

20-40msec

Question 2

What is the normal AH interval

Answer 2

50-120 msec

Question 3

What affects AH interval

Answer 3

Autonomic tone, drugs, pacing

Question 4

What causes prolongation of the PA interval

Answer 4

Disease of Atrium or Drugs

Question 5

What is a normal HV interval

Answer 5

35-55msec

Question 6

What 3 signals make up the PR interval

Answer 6

PA + AH + HV

Question 7

How is the AH interval measured?

Answer 7

A to HIS spike

Question 8

What does the AH interval represent?

Answer 8

AV Node conduction time

Question 9

What does the PA interval represent

Answer 9

Intra-atrial conduction time

Question 10

How is the PA interval measured

Answer 10

P to A on His catheter

Question 11

What does the steady lengthening of AH interval represent

Answer 11

Decremental conduction

Question 12

Do accessory pathways decrement?

Answer 12

No - They’re all or nothing

Question 13

‘Longest coupling interval that cannot initiate depolarisation’ - Describes……

Answer 13

Effective refractory period

Question 14

‘Longest coupling interval that that still depolarises…. but gives slowed conduction’ - Describes……

Answer 14

Relative refractory period

Question 15

‘Smallest possible time between two conducted impulses’ - Describes…….

Answer 15

Functional Refractory period

Question 16

Does the effective refractory period decrease at faster rates - YES/NO

Answer 16

Yes - Refractory rates decrease with quicker HR’s

Question 17

What is the normal effective refractory period of the Atrium

Answer 17

170 - 300ms

Question 18

What is the effective refractory period of the AVN

Answer 18

230 - 430ms

Question 19

What is the functional refractory period of the AVN

Answer 19

330ms - 500ms

Question 20

What is the effective refractory period of the Ventricle

Answer 20

180 - 280ms

Question 21

What is a normal SNRT

Answer 21

<1500ms

Question 22

How do you calculate cSNRT

Answer 22

SNRT - BCL

Question 23

What is a normal cSNRT

Answer 23

<525ms

Question 24

What are the positions in a 4 wire study

Answer 24

HRA
HIS
CS
RVA

Question 25

Where is the HRA and what does it give you

Answer 25

High RA / Gives you SN information and BCL

Question 26

Where is the HIS and what does it give you

Answer 26

Straddles TV - Records A, H and V signals

Question 27

Where is the CS and what does it give you

Answer 27

CS or AV Groove - Records LA & LV signals

Question 28

Where is the RVA and what does it give you

Answer 28

RV Apex - Records RV signals

Question 29

How do you measure BCL

Answer 29

A to A signal on HRA catheter

Question 30

What does the HV interval represent

Answer 30

Time in His-Purkinje system

Question 31

How do you measure the HV interval

Answer 31

H signal to earliest V