Shock Therapies

Question 1

Which shock therapies are non-committed in MDT ICD’s?

Answer 1

Initial VF detection and all cardioversions.

Question 2

What has to happen for a non-committed shock to be aborted (confirmation)?

Answer 2

“Four to abort.” There is a refractory window following charge completion that terminates with the next v sense. If the next four intervals are slower than the TDI, therapy will abort.

Question 3

How does Confirmation + work?

Answer 3

Confirmation + looks for four out of five slow intervals after the delivery of ATP or after charging is complete. Unlike Confirmation, Confirmation + looks for intervals that are within 60ms of the detected arrhythmia.

Question 4

When is a committed defib shock delivered following charge completion?

Answer 4

There is a 900 ms sync interval and if there is no R wave to sync the shock with, the charge is delivered without syncing.

Question 5

How long and when is the confirmation/arrhythmic window for Confirmation (no +)?

Answer 5

Longest programmed detection window enabled plus 60 ms. Two intervals less than the this interval/window will cause therapy delivery.

Question 6

What additional criteria is applied to Confirmation + under certain circumstances?

Answer 6

If the rhythm is detected in the VF zone and is polymorphic, the confirmation interval is FDI + 60 ms.

Question 7

How are the shock pathways labeled in MDT ICD’s?

Answer 7

Can = A, SVC = X, RV = B

Question 8

What is the nominal shock pathway?

Answer 8

B>AX (B to AX)