Ablation

Question 1

Is ablation considered unipolar or bipolar

Answer 1

Uni-polar

Question 2

5 Complications of Ablation procedure

Answer 2

SAME AS ANY CATHETER PROCEDURE

Pneumothorax
Tamponade
Perforation 
Dissection of vessle 
Haemothorax 
TIA or Stroke 

Ablation Specific - Oesophageal Fistula

Question 3

Two mechanisms of ablative heating

Answer 3

Resistive and Conductive

Question 4

Where does resistive heating take place

Answer 4

At point of contact with tissue

Question 5

Is resistive heating localized or does it radiate

Answer 5

Its localized

Question 6

90% of all ablative power is absorbed within what distance (mm)

Answer 6

1.5mm

Question 7

Resistive heating occurs with tissue and what else

Answer 7

Blood

Question 8

Is conductive localized

Answer 8

No, it radiates out from POC

Question 9

What percentage of the lesion does Conductive generate

Answer 9

90%

Question 10

Is resistive or conductive heating responsible for deep lesion penetration

Answer 10

Conductive is responsible for deep lesions

Question 11

Which form of heating continues when power is turned off

Answer 11

Conductive heating continues when power is removed

Question 12

Why is it important to understand conductive heating still takes place when power is removed

Answer 12

When ablating close to AV node, coming off at the first sign of block is important to minimise risk associated with conductive heating

Question 13

Which has lower resistance to energy - Blood/Tissue

Answer 13

Blood - Current will always prefer to travel via blood, therefore tip contact is crucial

Question 14

Why are low flow areas difficult to ablate

Answer 14

Low flow areas dont allow cooling - Therefore the tip gets hot very quickly, meaning energy can’t be delivered over a long period of time. Tissue stays cold = no lesion

Question 15

Why are high flow areas difficult to ablate

Answer 15

Lots of flow means lots of cooling - Therefore its difficult to reach target temperature

Question 16

What are 5 Determinants of lesion size

Answer 16

Quality of Contact
Duration of application
Electrode size
Impedance 
Tissue temperature

Question 17

At what temperature does myocardial injury occur

Answer 17

48-52 degrees centigrade

Question 18

What is the target temperature for the catheter tip

Answer 18

50-70 degrees centigrade

Question 19

What 3 things are likely to occur if the tip >100 degrees C

Answer 19

1 - Thrombi coagulation
2 - Serum Coagulum to the tip - Limiting lesion size
3 - Gas bubbles / Steam pop

Question 20

What style of catheter tip produces large but shallow lesions

Answer 20

Conventional tip

Question 21

What style of catheter tp produces large but deeper lesions with smaller surface areas at the top

Answer 21

Irrigated tip

Question 22

What is the purpose of Irrigated tip catheters

Answer 22

To produce deeper lesions vs. conventional

Question 23

How do irrigated catheters allow the production of deeper lesions

Answer 23

More power can be delivered without the tip becoming too hot as irrigation provides cooling - More power delivery = deeper lesions.