O Overview

g Assurrance
Sensing Assurance allows
s for automattic adjustmen
nts to program
mmed sensittivity in pacing devices, aiding in
ppropriate se
ensing during
g AF and pre
eventing overrsensing due to large T w
waves. It allow
ws for the automatic
djustment of atrial and ve
entricular sen
nsitivity levels
s in IPGs by monitoring P
P- and R-wavve values.
Sensing Assurance will ad
djust sensitivity only if the programmed
d mode allow
ws both senssing and pacing in a
hamber, with
h the exceptio
ons that adjustments are allowed in th
he VDD, AAI<
<=>DDD, an
nd AAIR<=>D
modes, and are not allowe
ed in the AAT
T/VVT modes
s. It is nomina
ally On.
To program th
his feature, go to Params -> Atrial / Ve
entricular Sen
 While Sensing Ass
surance is On
n, there are limits to man ually program
mming sensitivity values
ence table be
 Ventric
cular Safety Pacing (VSP
P) must be prrogrammed O
On for ventriccular Sensing
g Assurance
Feature Ope
The following steps describe how Sens
sing Assuran
nce operates..
Step 1: Devic
ce calculates
s Target Sen
nsing Margin
Each nonrefractory sensed ev
vent (AS or VS)
V is measu red and com
mpared to the Target Senssing
Margin, which varries dependin
ng on the sen
nsitivity settin
ng, the type o
of lead (A an
nd V) and its polarity.
See table
on the next
© 2013 Medtron
nic, Inc.
ww w.medtronic
Page 1 of 4
Chamber and Sensing Polarity
Target Sensing Margin
Atrial Bipolar
4.0 - 5.6 x (programmed value)
Atrial & Ventricular Unipolar
or Ventricular Bipolar
2.8 - 4.0 x (programmed value)
Example: A bipolar atrial lead set to 0.5 mV yields a target Atrial Sensing margin = 2.0 mV to 2.8 mV
(4 x 0.5 mV to 5.6 x 0.5 mV).
Step 2: Classification of each P wave
The sensed P wave is then classified as either a low, adequate, or high amplitude.
Step 3: Reprogramming sensitivity
If 17 consecutive beats are “Low,” the sensitivity is adjusted to the next programmable value that is
more sensitive. If 36 consecutive beats are “High,” the sensitivity is adjusted to the next less sensitive
Sensing Assurance will not adjust Sensitivity during temporary operation.
While Sensing Assurance is designed to adapt sensitivity margins in response to changes in sensed event
amplitudes, Sensing Assurance may not eliminate all sources of oversensing.
© 2013 Medtronic, Inc.
Page 2 of 4
Sensing Assurance Off:
When P wave amplitudes
decrease during atrial flutter,
the smaller P waves could be
undersensed (as shown in
the ECG to the right).
Sensing Assurance On:
When P wave amplitude
decreases during atrial flutter,
sensing assurance will
readjust the sensitivity level
to sense smaller P waves.
Performance Data
The following clinical data supports the need for an automatic sensing feature:
 Changes in P and R wave signal amplitudes may occur with lead maturation, myocardial infarction,
antiarrhythmia medications, atrial arrhythmias, and exercise.1
 Atrial arrhythmias and exercise have been shown to affect signal amplitudes.2
 Programming the sensitivity threshold and safety margin using the sinus rhythm signal amplitude may
not be adequate to sense the atrial events during the atrial arrhythmias.3
Adapta® DR, Adapta SR, Versa® DR, Sensia® DR, Sensia SR
1. Castro A, Liebold A, Vincente J, Dungan T, Allen JC Jr. Evaluation of autosensing as an automatic means of
maintaining a 2:1 sensing safety margin in an implanted pacemaker. Autosensing Investigation Team. PACE.
November 1996;19(11, Part II):1708-1713.
2. Frohlig G, Schwerdt H, Schieffer H, Bette L. Atrial signal variations and pacemaker malsensing during exercise: a study
in the time and frequency domain. J Am Coll Cardiol. April 1988;11(4):806-813.
3. Wood MA, Moskovljevic P, Stambler BS, Ellenbogen KA. Comparison of bipolar atrial electrogram amplitude in sinus
rhythm, atrial fibrillation, and atrial flutter. PACE. February 1996;19(2):150-156.
Source: Medtronic Adapta /Versa /Sensia Reference Guide.
This document is provided for general educational purposes only and should not be considered the exclusive source for this
type of information. At all times, it is the professional responsibility of the practitioner to exercise independent clinical judgment in
a particular situation. Changes in a patient’s disease and/or medications may alter the efficacy of a device’s programmed
parameters or related features and results may vary. The device functionality and programming described in this document are
based on Medtronic products and can be referenced in the published device manuals.
© 2013 Medtronic, Inc.
Page 3 of 4
Indications, Safety, and Warnings
Brief Statement: IPGs
Implantable pulse generators (IPGs) are indicated for rate adaptive pacing in patients who may benefit from increased pacing rates concurrent
with increases in activity and increases in activity and/or minute ventilation. Pacemakers are also indicated for dual chamber and atrial tracking
modes in patients who may benefit from maintenance of AV synchrony. Dual chamber modes are specifically indicated for treatment of
conduction disorders that require restoration of both rate and AV synchrony, which include various degrees of AV block to maintain the atrial
contribution to cardiac output and VVI intolerance (e.g. pacemaker syndrome) in the presence of persistent sinus rhythm. For the MR
Conditional IPG, a complete pacing system consisting of an RVDR01 IPG and 2 SureScan leads is required for use in the MR environment.
IPGs are contraindicated for dual chamber atrial pacing in patients with chronic refractory atrial tachyarrhythmias; asynchronous pacing in the
presence (or likelihood) of competitive paced and intrinsic rhythms; unipolar pacing for patients with an implanted cardioverter defibrillator
because it may cause unwanted delivery or inhibition of ICD therapy; and certain IPGs are contraindicated for use with epicardial leads and with
abdominal implantation.
Changes in a patient’s disease and/or medications may alter the efficacy of the device’s programmed parameters. Patients should avoid sources
of magnetic and electromagnetic radiation to avoid possible underdetection, inappropriate sensing and/or therapy delivery, tissue damage,
induction of an arrhythmia, device electrical reset or device damage. Do not place transthoracic defibrillation paddles directly over the device.
Potential Complications
Potential complications include, but are not limited to, rejection phenomena, erosion through the skin, muscle or nerve stimulation, oversensing,
failure to detect and/or terminate arrhythmia episodes, and surgical complications such as hematoma, infection, inflammation, and thrombosis.
See the device manual for detailed information regarding the implant procedure, indications, contraindications, warnings, precautions, and
potential complications/adverse events. For further information, please call Medtronic at 1-800-328-2518 and/or consult Medtronic’s website at
Caution: Federal law (USA) restricts these devices to sale by or on the order of a physician.
World Headquarters
Medtronic, Inc.
710 Medtronic Parkway
Minneapolis, MN 55432-5604
© 2013 Medtronic, Inc.
Tel: (763) 514-4000
Fax: (763) 514-4879
Toll-free: 1 (800) 328-2518
(24-hour technical support for physicians and medical professionals)
Page 4 of 4