RV Lead Integrity Alert (LIA) Feature
When evidence of a lead issue is detected, RV Lead Integrity Alert (LIA) is designed to reduce the patient’s risk of receiving multiple inappropriate shocks by extending the VF detection time, triggering programmable alerts and increasing diagnostic data collection and monitoring.
This feature can be found in some Medtronic ICD and CRT-D devices. Please go to manuals.medtronic.com or consult with your local Medtronic representative regarding device models available in your geography.
RV LIA is nominally programmed On. Additional programmable parameters for this feature include:
- Device Tone – If programmed On and alert conditions are met, the device will sound a tone every 4 hours and at the programmed alert time.
- Alert Urgency – Denotes tone that will sound.
- Patient Home Monitor – If set to "Yes" and the patient has a CareLink™ home monitor, and alert conditions are met, a CareAlert™ Notification will be sent to the CareLink Network. Patient Home Monitor is nominally set to "No" or off.
To program this feature, go to Params -> Alerts… -> Lead/Device Integrity Alerts… -> RV Lead.
Device Tone Programming
Patient Home Monitor Programming
RV LIA continually monitors RV pacing lead impedance measurements, the frequency of rapid nonsustained VT (NSVT) episodes, and the frequency of short ventricular intervals counted on the Sensing Integrity Counter (SIC).
RV LIA identifies a potential lead fracture if at least two of the following three criteria are met within the past 60 days of each other:
- Abnormal RV lead impedance (defined as impedance that is significantly higher or lower than a calculated baseline impedance level)
- Two or more High Rate-NS (nonsustained VTs) with intervals that are shorter than 220 ms
- At least 30 short V-V interval counts (SIC) within 3 consecutive days
Once the RV LIA criteria have been met, an alert will sound immediately, and then every 4 hours at 12:00, 4:00, 8:00 both am/pm. The tone will also sound at the programmed alert time and when a magnet is placed over the device. If the patient has a wireless device with the RV LIA CareAlert programmed On, and a CareLink home monitor, a CareAlert Notification will be sent to the CareLink Network.
In addition to the alert, the algorithm is designed to make certain automatic programming changes when the RV LIA criteria are met, in order to reduce the chance of inappropriate shocks due to sensing lead noise. Diagnostic data collection is also extended. The changes include:
- VF NID increased to 30/40 (if programmed to a lesser value)
- Monitor VT NID to 32
- AT/AF Detection to Monitor
- Pre-arrhythmia EGM storage set to On for 1 month when at least 1 High Rate NS episode has occurred.
- Tachyarrhythmia detection will be temporarily suspended automatically during a nonwireless device interrogation. The intent is to reduce the incidence of shocks from sensed interference during interrogation of a device with a fractured lead. During a programmer session, tachyarrhythmia detection can be resumed by:
- selecting "Resume" at the top of the programmer screen, or
- by removing the programmer head, or
- by ending the session and removing the programmer head
- The Sensing Integrity Counter total is displayed on the Battery and Lead Measurements screen. This number represents the number of short ventricular intervals that occurred since the last patient session. Therefore, the total could exceed 30 without satisfying the alert criteria if the total was reached during a period of more than 3 consecutive days.
- If both the Device Tone and the Patient Home Monitor alert parameters for RV LIA are programmed to Off, the device does not trigger an alert tone or a CareAlert Notification, and it does not adjust tachyarrhythmia detection parameters. However, it records a Quick Look™ II Observation for the lead warning, and it makes adjustments to EGM storage.
- RV LIA does not operate if VF detection/therapies are programmed Off. LIA operation resumes when VF detection/therapies are programmed back On and only data collected after that time is applied to the alert criteria.
- Lead Impedance alerts are programmed separately from the RV LIA. Therefore, if the RV lead impedance is detected as out of range, an RV Lead Impedance alert may be triggered separately or in conjunction with the RV LIA alert.
Evaluation of RV Lead Integrity Alert
If the device is sounding an alert tone, or if the programmer indicates that an alert has occurred, review the alert messages and evaluate the diagnostic data to determine the likelihood of a lead integrity issue. When the device is interrogated, a CareAlert pop-up window will appear to notify the clinician of the alert condition.
The Quick Look II Observations will verify there is an RV Lead Integrity Warning. Finally, select Alert Events under the Data icon to see the CareAlerts Events list for date, time and details of the Alert Event.
The example below shows a RV Lead Integrity Alert triggered for a lead fracture. The patient heard an alert tone and presented to the clinic. The Impedance Trend shows a lead impedance crossing > 1,000 ohms on September 21. The Lead Integrity Alert (LIA) is triggered.
Satisfying the impedance threshold component of LIA triggers additional EGM storage in the nonsustained log for V. cycle < 220 ms.
The stored EGM is assessed to determine the cause of the alert. This EGM confirms noise detected on the tip to ring EGM – lead fracture is suspected. The physician intervenes to prevent the patient from receiving an inappropriate shock.
RV Lead Integrity Alert can decrease inappropriate shocks.1 RV Lead Integrity Alert has been demonstrated to provide at least 3 days advanced warning in three out of four patients with a Medtronic Fidelis lead fracture.1-4 Ellenbogen and his colleagues performed a retrospective analysis comparing the performance of LIA with that of conventional impedance monitoring for identifying pace-sense lead failure in lead families that differ from Medtronic Fidelis leads in either functional design or primary failure mode. They found that the LIA algorithm increased the detection rate of true lead failures for both integrated bipolar leads and dedicated bipolar leads. LIA was also associated with a low incidence of inappropriate shocks, and was triggered despite normal impedance trends. For St. Jude Riata and Durata leads, and Boston Scientific Endotak leads, Lead Integrity Alert detected more lead issues than lead impedance monitoring alone.5
- Swerdlow CD, Gunderson B, Ousdigian K, Sachanandani H, Ellenbogen K. HRS Conference 2010.
- Patel AS, et al. Modification to Lead Integrity Alert Improves Performance. HRS Conference, 2009.
- Gunderson BD, Patel AS, Bounds CA, et al. J Am Coll Cardiol. November 2, 2004;44(9):1898-1902.
- Swerdlow CD, Gunderson BD, Ousdigian KT, et al. Circulation. November 11, 2008;118(21):2122-2129.
- Ellenbogen KA , Gunderson BD, Stromberg KD, et.al. Circ Arrhythm Electrophysiol. 2013;6:1169-1177.
Sources: Medtronic Protecta™ XT DR Clinician Manual; Medtronic Protecta™ XT CRT-D Clinician Manual.