BScientific lessons Flashcards
What preparation do I need before a pacemaker replacement procedure?
details of the device type, date of implant and model
Check lead header compatibility
Older connector pins such as 3.2 mm LP may require an adapter and must use a device with a IS-1 compatible header (which has longer ports and sealing rings)
3.2 mm LP pin is longer and has no sealing rings
An IS-1 compatible header can be used with a lead with IS-1 terminal pin but is not ideal since the terminal pin will not reach the terminal port and the redundant sealing rings will make it more difficult to insert the lead fully into the header
What is the purpose of Automatic Lead Recognition?
Automatic Lead Recognition is intended for pacemaker and CRT-P surgical implant without a programmer. It is nominally ON and it allows the device to exit storage mode by automatically recognizing when an RV lead is connected to the device and it detects if the inserted lead is unipolar or bipolar and automatically adjusts the pacing and sensing polarity according to the lead type. ALR mitigates the potential for non-pacing when a bipolar configured device is used with a unipolar lead, although the device must be in the pocket for for pacing to deliver pacing.
How does Automatic Lead Recognition work?
It uses the bipolar impedance to determine the lead configuration: if the bipolar impedance is within normal range, the lead with continue to pace and sense in bipolar configuration. If the impedance is out of range, pace and sense polarity change to unipolar. It will continue to monitor bipolar impedance for another 2 hr, after that if still out of range, lead will continue in unipolar sense and pace until manually reprogrammed.
Why Automatic Lead Recognition is not recommended in ICDs?
Unipolar pacing configuration is contraindicated for patients with ICD, therefore ALR must be programmed OFF prior to ICD implant.
What is PVARP and its function?
PVARP: is a refractory period on the atrial channel following VS or VP event. The purpose of the PVARP is to prevent the atrial channel from sensing a variety of signals such as retrograde P waves related to retrograde VA conduction, very early atrial APBs, and far-field V signals potentially registered on the A channel.
What is the purpose of A and V blanking periods? (PVAB and PAVB)
A and V blanking are designed to prevent potential cross-talk or inappropriate cross-chamber detection, i.e sensing V activity on the A channel or the opposite. For example: after VP or VS an atrial blanking period is initiated to avoid atrial sensing of the ventricular activity. After AP a ventricular blanking period will avoid ventricular sensing of the atrial activity.
Define LRL and explain how it works in a DDD mode device?
LRL is the longest VP-VP or AP-AP intervals that the pacemaker will allow and determine whether the pacemaker will pace the atrium.
The relationship between the intrinsic PR interval and the programmed AV delay intervals determines whether there is pacing in the ventricles.
What is the MTR?
How is VA interval calculated?
What is ventricular refractory period?
What is TARP?
Total atrial refractory period. TARP = AVD + PVARP
