Medtronic MC1AVR1 Reference Guide
Micra™ AV MC1AVR1
MR Conditional dual chamber transcatheter pacing system with SureScan™ technology
(VDD)
Reference Manual
Caution: Federal law (USA) restricts this device to sale by or on the order of a physician.
Micra™ AV MC1AVR1
Reference Manual
This manual describes the operation and intended use of the features of the Micra AV Model
MC1AVR1 MR Conditional dual chamber transcatheter pacing system with SureScan™
technology (VDD).
The following list includes trademarks or registered trademarks of Medtronic in the United
States and possibly in other countries. All other trademarks are the property of their respective
owners.
Capture Management, CareLink, CareLink Encore, Medtronic, Medtronic CareLink, Micra,
Quick Look, SureScan
Medtronic
Micra™ AV MC1AVR1
Contents
1 Introduction .......................................................... 6
1.1 About this manual .................................................... 6
2 Patient follow-up guidelines ........................................... 8
2.1 Follow-up appointments .............................................. 8
2.2 Optimizing device longevity ........................................... 10
3 Diagnostic data features ............................................. 12
3.1 Quick Look II summary data .......................................... 12
3.2 Rate histograms .................................................... 13
3.3 Battery and device performance data .................................. 14
4 Configuring pacing therapies ......................................... 19
4.1 Sensing ........................................................... 19
4.2 Single chamber pacing therapies ..................................... 31
4.3 Dual chamber modes ............................................... 33
4.4 Rate-responsive pacing ............................................. 43
4.5 Pacing with Capture Management .................................... 50
4.6 Rate Hysteresis .................................................... 57
Glossary ................................................................. 59
Index .................................................................... 63
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1 Introduction
1.1 About this manual
This manual describes the operation and intended use of the features of the Micra AV Model
MC1AVR1 MR Conditional dual chamber transcatheter pacing system with SureScan™
technology (VDD).
Throughout this manual, the word “device” refers to the implanted Micra AV device.
The report images, labels, and navigation instructions in this manual apply to the Medtronic
Model SW044 software running on a Medtronic Model 2090 Programmer or a Medtronic
Encore Model 29901 Programmer. The details of the user interface are provided for
reference only and may not match those of other applications.
Navigation paths to software screens or programmable parameters are shown with a >
character between each step in the path (for example, Params > Capture Management… >
Amplitude Safety Margin).
1.1.1 Product literature
Before implanting the device, it is recommended that you take the following actions:
●
Read the product literature for information about prescribing, implanting, and using the
device and for conducting a patient follow-up session.
●
Thoroughly read the technical manuals for the other system components.
●
Discuss the device and implant procedure with the patient and any other interested
parties, and give them any patient information materials packaged with the device.
The following manuals and documents contain additional information about the programmer
and implanted device:
Device manual – This manual provides summaries of device features, indications and
contraindications, warnings and precautions, instructions for implanting the device, quick
reference specifications, parameter tables, and an explanation of package symbols.
MRI technical manual – This manual provides MRI-specific procedures and warnings and
precautions.
Programming guide – This manual explains how to use the programmer software to
conduct a patient session.
Programmer reference manual – This manual provides a detailed description of the
Medtronic programmer. There is a programmer reference manual for the Medtronic
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CareLink Model 2090 programmer and a programmer reference manual for the Medtronic
CareLink Encore 29901 programmer.
Radio regulatory compliance information – This document provides compliance
information related to the radio components of the device.
Micra™ AV MC1AVR1
1.1.2 Technical support
Medtronic employs highly trained representatives and engineers located throughout the
world to serve you and, upon request, to provide training to qualified hospital personnel in the
use of Medtronic products.
In addition, Medtronic maintains a professional staff of consultants to provide technical
consultation to product users.
For more information, contact your local Medtronic representative, or call or write Medtronic
at the appropriate address or telephone number listed on the back cover.
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2 Patient follow-up guidelines
2.1 Follow-up appointments
Schedule regular patient follow-up sessions during the service life of the device. The first
follow-up session should occur within 72 hours of implant so that the patient can be checked
for device dislodgment, wound healing, and postoperative complications.
During the first few months after implant, the patient may require close monitoring. Schedule
follow-up sessions at least every 3 months to monitor the condition of the patient and the
device and to verify that the device is configured appropriately for the patient.
2.1.1 Follow-up process
The process for conducting a follow-up evaluation includes the following steps:
1. Review the patient’s presenting rhythm, including an ECG.
2. Verify the status of the implanted device.
3. Verify the clinical effectiveness of the implanted device.
4. During a follow-up appointment, adjust device parameters as necessary.
2.1.2 Reviewing the presenting rhythm
The presenting rhythm may indicate the presence of undersensing and oversensing or
ventricular loss of capture. These are pacing issues that can affect the delivery of pacing
therapy. These issues can often be resolved by making programming changes.
Review the presenting rhythm by viewing the Live Rhythm Monitor and recording the EGM,
ECG, and marker annotations. If you identify issues with the patient’s presenting rhythm,
review the device settings and reprogram the device to values that are appropriate for the
patient.
2.1.3 Verifying the status of the implanted device
Perform the following tasks to verify that the device is functioning correctly:
●
Assess the battery status.
●
Review the device status information on the Quick Look II screen.
●
Review any Observations on the Quick Look II screen.
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2.1.3.1 Assessing the battery status
To assess the status of the device battery, review the Remaining Longevity estimate on the
Quick Look II screen. If the device battery has reached a replacement threshold, the
associated indicator is displayed. For more detail about the battery status, including battery
voltage, review the Battery and Device Measurements data: tap the next to the Remaining
Longevity field on the Quick Look II screen.
Warning: When the battery voltage reaches the End of Service (EOS) condition, the device
permanently deactivates pacing and sensing and switches to the Device Off mode. The EOS
symbol appears on the programmer screen.
If the Recommended Replacement Time (RRT) indicator or Elective Replacement Indicator
(ERI) is displayed or if the battery voltage is at or below the displayed RRT voltage, contact
your Medtronic representative and schedule an appointment with the patient to implant a
new device. For more information about the replacement indicators, see the Micra AV
SW044 Programming Guide.
2.1.3.2 Assessing the performance of the device
Follow-up appointment – During a follow-up appointment, you can check the performance
of the device by reviewing the electrode impedance, capture threshold, and sensing trends
on the Quick Look II screen. To view this information, tap Data > Quick Look II. For a more
detailed history of each measurement, tap the next to the appropriate trend graph. For
more information about the automatic collection of these trends, see Section 3.3, “Battery
and device performance data”, page 14.
If you also want to gather real-time information about the performance of the device, you can
perform the following tests:
●
Impedance test: Compare the results of the test to previous electrode impedance
measurements to see if there have been significant changes since the last follow-up
session.
●
Threshold test: Perform this test to check the patient’s Capture Management thresholds.
●
Sensing test: Compare the test results to previous R-wave amplitude measurements.
For more information about performing these tests, refer to the Micra AV SW044
Programming Guide.
2.1.4 Verifying the clinical effectiveness of the implanted device
You can use the information available from the Quick Look II screen and in printed reports to
assess whether the device is providing adequate clinical support for the patient.
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2.1.4.1 How to assess effective pacing therapy
1. Interview the patient to confirm that the patient is receiving adequate cardiac support for
daily living activities.
2. Review the pacing percentages on the Quick Look II screen and the Data – Rate
Histograms window. Print a Rate Histograms Report. You can use the data on the rate
histogram window and in the report to assess the patient’s pacing and sensing history.
For more information about rate histograms, see Section 3.2, “Rate histograms”,
page 13.
3. You can use the data on the A4 Amplitude Trend to assess changes in atrial sensing
over time. Review the A4 Amplitude Trend data. Tap Data > Diagnostics > A4 Amplitude
Trend > Open Data.
2.1.5 Adjusting device parameters
Adjust the pacing and diagnostic data parameters as needed to address any issues
identified during the follow-up appointment.
Note: Use caution when reprogramming the sensing parameters to ensure that appropriate
sensing is maintained. For more information, see Section 4.1, “Sensing”, page 19.
2.2 Optimizing device longevity
Optimizing device longevity is a desirable goal because it may reduce the frequency of
device replacement for patients. Optimizing device longevity requires balancing the benefit
of device therapy and diagnostic features with the energy requirements placed on the battery
for the operation of these features.
To view the Remaining Longevity estimate for the device, refer to the Quick Look II screen.
For information about the longevity of the device, see the Micra AV MC1AVR1 Device
Manual.
The following sections describe strategies that can help to reduce the energy requirements
placed on the battery.
2.2.1 Managing pacing outputs
Capture Management – The Capture Management feature provides the device with
automatic monitoring and follow-up capabilities for managing pacing thresholds in the right
ventricle. This feature is designed to monitor the pacing threshold and, optionally, to adjust
the pacing outputs to maintain capture. Programming the Capture Management feature to
the Adaptive mode allows the device to set the pacing amplitude just high enough to maintain
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capture while preserving battery energy. For more information, see Section 4.5, “Pacing with
Capture Management”, page 50.
Manual optimization of amplitude and pulse width – If you choose to program the
Capture Management feature to Monitor or Off, you can optimize the patient’s pacing output
parameters manually. Perform a pacing threshold test to determine the patient’s pacing
threshold. Select amplitude and pulse width settings that provide an adequate safety margin
above the patient’s pacing threshold. An adequate safety margin decreases the pacing
outputs and conserves battery energy. Refer to the Micra AV SW044 Programming Guide for
more information about performing a pacing threshold test.
Pacing rate – The more paced events that are delivered, the more battery longevity is
reduced. Make sure that you have not programmed an unnecessarily high pacing rate for the
patient. Carefully consider using features that increase the bradycardia pacing rate. Use
features such as Rate Response only for patients who can receive therapeutic benefit from
the feature.
Micra™ AV MC1AVR1
2.2.2 Other longevity considerations
Atrial mechanical sensing – Atrial mechanical sensing (the VDD, VDI, or ODO pacing
modes) decreases battery longevity. The AV Conduction Mode Switch feature disables atrial
mechanical sensing during periods of intact AV conduction, reducing the longevity impact.
Programming the sum of 3 vectors for atrial sensing (A. Sensing Vector) has a minor negative
impact on battery longevity.
Holter telemetry – Extended use of the Holter telemetry feature substantially decreases the
battery longevity. The Holter telemetry feature continues to transmit EGM and marker
annotations for the programmed time duration, regardless of whether the programming head
is positioned over the device.
Note: Do not program the Holter telemetry feature to On unless instructed to do so by a
Medtronic representative. Use of this feature requires that the patient is equipped with a
customized Holter monitor provided by Medtronic for monitoring EGM.
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3 Diagnostic data features
3.1 Quick Look II summary data
At the start of a patient session, it is useful to quickly view summary information about device
operation and the patient’s condition. This overview can help you to determine whether you
need to look more closely at diagnostic data or reprogram the device to optimize therapy for
the patient.
The Quick Look II data summarizes the most important indicators of system operation and
the patient’s condition. These indicators include battery and device status, pacing therapy
information, and system-defined observations.
You can view Quick Look II data on the Quick Look II screen, which is displayed on the
programmer at the beginning of a patient session. To return to the Quick Look II screen from
another screen, tap Data > Quick Look II. For more information about using the Quick Look
II screen, refer to the Micra AV SW044 Programming Guide.
3.1.1 Quick Look II battery and device status information
The Quick Look II data includes the following information about the battery and device
status:
●
Estimate of remaining battery longevity
●
Trends of the weekly average impedance, capture threshold, and R-wave amplitude
measurements
●
Most recent measured values for impedance, capture threshold, and R-wave amplitude
3.1.2 Quick Look II pacing therapy information
The Quick Look II data includes the following information about pacing therapy:
●
Programmed values for the Mode, Lower Rate, and Upper Tracking Rate parameters
●
Percentage of time (% of Time) spent in sensing or pacing since the last patient session
●
Percentage of time spent in AV Conduction Mode Switch, if applicable
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3.1.3 Quick Look II Observations
Observations are based on an analysis of programmed parameters and data collected since
the last session. The following types of observations can occur:
●
Device status observations inform you of conditions that affect device operation and
require attention. Examples of such conditions include Recommended Replacement
Time (RRT) or the occurrence of a device reset.
●
Electrode status observations report any potential issues with the sensing integrity of the
electrodes and abnormal Capture Management results. These observations can also
warn you about possible inconsistencies in the performance of the device.
●
Diagnostic data observations report noteworthy events, such as conditions that prevent
diagnostic data from being collected effectively.
●
Clinical status observations alert you to abnormal patient conditions, such as high
pacing thresholds and a potential lack of effective VDD therapy.
On the Quick Look II screen, if you select one of the displayed observations and more
information about the selected observation is available, the becomes active. You can use
the to look at the relevant details.
3.2 Rate histograms
Information about heart rates recorded between patient sessions can help you to monitor a
patient’s condition to assess the effectiveness of therapies. Rate histograms show the
distribution of atrial mechanical sensed-ventricular paced (AM-VP) events, atrial mechanical
sensed-ventricular sensed (AM-VS) events, ventricular sensed (VS) only events, and
ventricular paced (VP) only events.
To access the rate histograms data, select Data > Diagnostics > Rate Histograms > [Open
Data].
3.2.1 Information provided by rate histograms
Rate histograms report the atrial and ventricular event data stored by the device. There are
histograms for 2 types of heart rate data: ventricular rate and atrial ventricular (AV) rate. The
histograms include data from the current collection period. Data storage for rate histograms
is automatic; no setup is required.
The rate histogram shows the percentage of time that the device was pacing and sensing
within rate ranges. There are 20 rate ranges that are each 10 bpm in length. Rates slower
than 40 bpm are included in the < to 40 range; rates faster than 220 bpm are included in the
220 to > range.
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% of Time – This section shows the percentage of the total time that the device paced or
sensed during the collection period. If atrial data was collected during this time, the device
will also show the percent of events that were preceded by an atrial mechanical sense
(AM-VP and AM-VS).
Atrial ventricular rate histogram – The atrial ventricular rate histogram shows the rate
distribution of ventricular events, both ventricular sense (VS) and ventricular pace (VP),
denoting which ventricular events were preceded by atrial mechanical sensing events
(AM-VS and AM-VP). This rate histogram appears only when atrial data has been collected.
Ventricular rate histogram – The ventricular rate histogram shows the rate distribution of
ventricular sensed and paced events.
3.3 Battery and device performance data
The device automatically measures and records battery and device performance data every
day. This information can help you assess the status of the device battery and identify issues
with performance. The device records the following types of performance data:
●
Remaining longevity estimate and replacement indicators
●
Electrode impedance trend
●
Sensing amplitude trends (R-wave amplitude and A4 amplitude)
●
Capture threshold trend
●
Sensing integrity counter
You can access battery and device performance data from several different screens on the
programmer:
●
Quick Look II screen: Data > Quick Look II
●
Battery and device measurements window: Data > Diagnostics > Battery and Device
Measurements > Open Data
●
Electrode impedance window: Data > Diagnostics > Electrode Impedance Trend >
Open Data
●
Capture threshold window: Data > Diagnostics > Capture Threshold Trend > Open Data
●
R-wave amplitude window: Data > Diagnostics > R-Wave Amplitude Trend > Open Data
●
A4 amplitude window: Data > Diagnostics > A4 Amplitude Trend > Open Data
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3.3.1 Remaining Longevity estimate and replacement indicators
The device automatically measures the battery voltage once a day at 02:30. The automatic
daily battery voltage measurement is displayed on the Data – Battery and Device
Measurements screen.
The programmer is able to estimate the remaining device longevity (the number of years until
the battery reaches RRT) after 11 days of the device manufacture date. Longevity estimates
are based on a history of battery voltage measurements made by the device since the
manufacture date.
The Battery and Device Measurements screen provides the mean (Estimated at), minimum,
and maximum values for remaining longevity. These values are based on a statistical
analysis of accelerated battery discharge data. The maximum and minimum remaining
longevity estimates are 95th percentile values calculated from the distribution of this data.
That is, approximately 95% of devices are expected to reach RRT before the reported
maximum value and approximately 95% of devices are expected to reach RRT after the
reported minimum value.
If the device longevity estimator determines that there are less than 6 months (180 days) until
the End of Service (EOS), the programmer displays the RRT symbol and the date when the
battery reached the RRT condition. If the programmer displays the RRT symbol, contact your
Medtronic representative and schedule a patient appointment to implant a new device.
The expected service life of the device after RRT, defined as the Prolonged Service Period
(PSP), is 6 months (180 days). After the first 90 days of the PSP have passed, the device
reaches the Elective Replacement Indicator (ERI) and the programmer displays the ERI
indicator.1 When the device reaches the ERI condition, it automatically changes the pacing
mode to VVI and sets the pacing rate to 65 bpm, unless the device is programmed to a
non-pacing mode. It also changes Rate Hysteresis to Off if this feature is programmed to
On. When the ERI indicator is displayed on the programmer, implant a new device
immediately. For more information, see the Micra AV SW044 Programming Guide. The
device reaches End of Service (EOS) based on battery voltage and switches to the Device
Off mode, permanently deactivating the pacing operation. The programmer displays the
EOS symbol.
1
Note: After ERI, all pacing parameters can be programmed, including mode and rate.
Reprogramming the pacing parameters may reduce the duration of the ERI to EOS period.
Warning: When the battery voltage reaches the EOS condition, the device permanently
deactivates pacing and sensing and switches to the Device Off mode. The EOS symbol
appears on the programmer screen.
1
ERI may be indicated before the end of 90 days, and EOS may be indicated before the end of 180 days if the
actual battery usage exceeds the expected conditions during the Prolonged Service Period. For an explanation
of these conditions, see the Micra AV MC1AVR1 Device Manual.
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3.3.2 Electrode impedance trend
Every day at 02:30, the device delivers a ventricular pace and automatically measures the
electrode impedance. If the intrinsic heart rate is faster than the programmed pacing rate, the
device increases the pacing rate to be slightly faster than the intrinsic rate for 1 interval.
The daily automatic electrode impedance measurements are displayed on the Electrode
Impedance Trend screen, which plots the data as a graph. The graph shows up to 15 of the
most recent measurements and up to 80 weekly summary measurements, providing
minimum and maximum values for each week. Significant or sudden changes in electrode
impedance may indicate a problem with the pacing electrode.
If the device is unable to perform automatic electrode impedance measurements, gaps are
present in the trend graph.
3.3.3 Sensing amplitude trend
After completing the electrode impedance measurement, which starts at 02:30 every day,
the device begins to measure the amplitude of intrinsic ventricular sensed events. The
device attempts to measure the amplitude of 5 normal intrinsic ventricular sensed events.
After collecting these measurements, the device records their median value as the most
recent R-wave amplitude measurements. If the device has not collected 5 amplitude
measurements for the day by midnight, no measurement is recorded. The sensing amplitude
trend graph shows a gap for that day.
Note: The A4 Amplitude Trend measures the maximum acceleration in the A4 window,
which may not be the true A4 amplitude if the A4 signal does not occur in the A4 window.
The daily automatic sensing amplitude measurements are displayed on the R-Wave
Amplitude Trend and A4 Amplitude Trend windows, which plot the data as a graph. The
graph shows up to 15 of the most recent measurements and up to 80 weekly summary
measurements, providing minimum and maximum values for each week. Significant or
sudden changes in the R-wave amplitude may indicate a problem with the sensing
electrode. Significant or sudden changes in the A4 amplitude may indicate a problem with
effective VDD pacing therapy.
When operating in the VDD mode, the device periodically collects A4 amplitude
measurements over the course of the day. The A4 amplitude is measured as the maximum
acceleration in the A4 window. This measurement is collected regardless of whether an atrial
sense occurred in that cycle. At the end of the day at midnight (00:00), the device stores the
most common measured A4 amplitude of the day in the A4 Amplitude Trend. If the device has
not collected enough measurements for the day, no measurement is recorded. The A4
Amplitude Trend graph shows a gap for that day. This gap can happen if the device does not
spend enough time per day operating in the VDD mode.
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To view the R-wave sensing amplitude trend, tap Data > Diagnostics > R-Wave Amplitude
Trend > Open Data.
To view the A4 sensing amplitude trend, tap Data > Diagnostics > A4 Amplitude Trend >
Open Data.
Micra™ AV MC1AVR1
3.3.4 Capture threshold trend
If the Capture Management feature is programmed to Adaptive or Monitor, the device
automatically performs daily pacing threshold searches and records the results in the
Capture Threshold Trend data. In the adaptive mode, Capture Management also performs
hourly pacing threshold confirmation checks. For more information about Capture
Management, see Section 4.5, “Pacing with Capture Management”, page 50.
The results of the most recent daily pacing threshold measurements are displayed on the
Data – Trends window on the capture threshold trend graph. The graph shows up to 15 of the
most recent measurements and up to 80 weekly summary measurements, including
minimum and maximum values for each week. The Capture Threshold window also shows
programmed values for pacing output and Capture Management parameters, the last
measured threshold value, and a link to a detailed view of the last 15 days of the threshold
measurement data.
The Capture Management (Last 15 days detail) window shows daily results from the last 15
days of threshold measurements. These results include the dates, times, threshold
measurements, pacing amplitude values, and notes describing the results of each pacing
threshold search.
The Capture Threshold trend data provides a means to evaluate the operation of Capture
Management and the appropriateness of the current pacing output values. In addition,
sudden or significant changes in the pacing threshold may indicate a problem with the
pacing electrode.
Note: It is possible for a high threshold observation to occur without a corresponding value
shown on the Capture Threshold Trend graph. The observation occurs when a single
Capture Management test is aborted due to a high threshold value. When a single Capture
Management test is aborted due to a high threshold value, the device attempts a new
Capture Management test an hour later. If the new test does not result in a high threshold
value, the device stores this result in the Capture Threshold Trend for the day. If 3 consecutive
Capture Management tests are aborted due to a high threshold, a threshold value of > 5.0 V
is stored in the Capture Threshold Trend. The device does not attempt any more Capture
Management tests for that day.
To view the capture threshold trend on the programming screen, tap Data > Diagnostics >
Capture Threshold Trend > Open Data.
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3.3.5 Sensing Integrity Counter
The Sensing Integrity Counter records the number of short ventricular intervals that occur
between patient sessions. A large number of short ventricular intervals may indicate
oversensing.
To view the Sensing Integrity Counter on the programming screen, tap Data > Diagnostics >
Battery and Device Measurements > Open Data.
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4 Configuring pacing therapies
4.1 Sensing
Effective sensing is essential for the safe and effective use of the device. The device must
sense the occurrence of intrinsic cardiac events while avoiding oversensing so that it can
deliver therapies appropriately. Effective ventricular sensing can reduce the effects of long
depolarizations after paced events, oversensing the same event, and sensing T-waves,
noise, and interference. Effective atrial sensing can improve the efficacy of VDD pacing
therapy.
Programmable blanking periods and atrial refractory periods help to screen out extraneous
sensing or to prevent the device from responding to it. Both blanking periods and atrial
refractory periods follow pacing pulses and sensed events. Sensing is inhibited during
blanking periods. The device is able to sense events that occur during atrial refractory
periods, but it marks them as refractory events. Refractory events generally have no effect on
the timing of subsequent pacing events.
4.1.1 Ventricular sensing
The device senses electrically in the right ventricle. No sensing occurs in the left ventricle.
Each sensitivity setting represents a threshold value that defines the minimum electrical
amplitude recognized by the device as a sensed event in the right ventricle. Selecting a
higher value for the sensing threshold reduces the sensitivity to lower amplitude signals.
4.1.1.1 Operation of ventricular sensing threshold
Ventricular sensing operates at a fixed, programmed ventricular sensitivity.
4.1.1.2 Operation of ventricular blanking periods
Ventricular blanking periods follow paced and sensed ventricular events. Ventricular
blanking periods help to prevent the device from sensing pacing pulses, post-pacing
depolarization, T-waves, and oversensing of the same event.
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Ventricular
blanking
Markers
Medtronic Micra™ AV MC1AVR1
Figure 1. Programmable blanking periods
1 For the duration of this ventricular blanking period, which is defined by the Blank Post VS
parameter, ventricular sensing is disabled after a sensed ventricular event.
2 For the duration of this ventricular blanking period, which is defined by the Blank Post VP
parameter, ventricular sensing is disabled after a paced ventricular event.
4.1.1.3 Noise reversion in the VVI and VVIR modes
The operation associated with continuous noise sensing is called noise reversion. During
continuous noise reversion, ventricular sensing is disabled and ventricular pacing occurs at
the sensor-indicated rate in the VVIR mode and at the programmed lower rate in the VVI
mode.
4.1.1.4 Preventing noise sensing
Noise reversion may be caused by electromagnetic interference (EMI) or low sensitivity
settings. You can reduce or eliminate noise reversion by one of the following actions:
●
Identify the source of EMI and increase the distance between the patient and the EMI
source.
●
Reprogram Sensitivity to a less sensitive setting (higher numerical value).
●
Reprogram Blank Post VP and Blank Post VS to blank the T-waves.
4.1.1.5 Ventricular sensing parameters
Table 1. How to navigate to ventricular-electrical sensing parameters
Parameters Path
RV Sensitivity Params > Sensitivity
Blank Post VP
Blank Post VS
Params > RV Blanking
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4.1.2 Atrial mechanical sensing
Although the device is located entirely in the right ventricle, mechanically sensing the atrium
from the ventricle makes it possible to provide AV synchronous pacing for patients with AV
block. The device senses and paces electrically in the right ventricle. The device also uses
an accelerometer to detect the mechanical vibrations produced by the atrial contraction,
called A4. The ventricular contraction and relaxation also produces mechanical vibrations,
called A1, A2, and A3. The timing of A1, A2, A3, and A4 is similar to the heart sounds S1, S2,
S3, and S4, respectively.
Warning: Patient activities and environments which present mechanical vibrations to the
patient can interfere with the mechanical sensing of atrial contractions. This can result in loss
of AV synchrony.
The signals are defined as follows:
●
The A1 signal:
– Occurs at the beginning of ventricular systole and represents the closing of the mitral
valve and the tricuspid valve
– Occurs after the beginning of the QRS complex on an ECG
●
The A2 signal:
– Occurs at the completion of ventricular systole and represents the closing of the aortic
valve and the pulmonary valve
– Occurs near the end of the T-wave on an ECG
●
The A3 signal:
– Occurs during ventricular diastole
– Occurs after the T-wave on an ECG
– Corresponds in timing to the E-wave on a Doppler echo
– Represents the passive filling of blood from the atrium into the ventricle
●
The A4 signal:
– Occurs when the atrium contracts and pushes blood into the ventricle
– Occurs after the P-wave on an ECG
– Corresponds in timing to the A-wave on a Doppler echo
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