SPRINT QUATTRO SECURE MRI™ SURESCAN™ 6947
MR Conditional, steroid-eluting, quadripolar, screw-in, ventricular lead with RV/SVC defibrillation coil electrodes
Technical Manual
Caution: Federal law (USA) restricts this device to sale by or on the order of a physician.
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.
Evera, Evera MRI, Medtronic, Sprint Quattro, Sprint Quattro Secure, Sprint Quattro Secure MRI, SureScan, Tensi-Lock
Contents
1 Description 3
2 Indications 4
3 Drug component description 4
4 Contraindications 4
5 Warnings and precautions 4
6 Drug information 6
7 Pharmacodynamics of the Model 6947 lead 6
8 Adverse events and clinical trial data 7
9 Implant procedure 8
10 Specifications (nominal) 13
11 Medtronic warranty 14
12 Service 14
1 Description
The Medtronic Sprint Quattro Secure MRI SureScan 6947 lead is
a steroid-eluting, quadripolar, screw-in, ventricular lead with right
ventricular (RV) and superior vena cava (SVC) defibrillation coil
electrodes. This lead is designed for pacing, sensing,
cardioversion, and defibrillation therapies. The lead has been
tested for use in the Magnetic Resonance Imaging (MRI)
environment. The following lead lengths are MR Conditional:
58 cm and 65 cm. Other lead lengths are not MR conditional. The
lead also features Tensi-Lock and silicone-backed defibrillation
coils1.
The lead features an extendable and retractable helix electrode,
silicone insulation, and parallel conductors. The 4 electrodes of
the lead are the helix, ring, RV coil, and SVC coil.
●
The tip electrode is common to the connector pin of the IS-1
BI connector.
●
The ring electrode is common to the connector ring of the IS-1
BI connector.
●
The RV coil electrode is common to the connector pin of the
RV DF-13 connector (red band).
●
The SVC coil electrode is common to the connector pin of the
SVC DF-1 connector (blue band).
The RV and SVC coils deliver cardioversion and defibrillation
therapies. Pacing and sensing occur between the helix and
ring electrodes.
The helix electrode is made of platinized platinum alloy that can be
actively fixed into the endocardium. The helix electrode can be
extended or retracted by rotating the IS-1 connector pin with the
fixation tool.
The IS-1 bipolar leg of the trifurcation features a lumen for stylet
passage. The DF-1 connectors do not accept stylets.
The distal tip contains a nominal dosage of 685 µg of
dexamethasone acetate and 59 µg of dexamethasone sodium
phosphate. Upon exposure to body fluids, the steroids elute from
the lead tip. The steroids are known to suppress the inflammatory
response that is believed to cause threshold rises typically
associated with implanted pacing electrodes.
1.1 Medtronic SureScan system
A complete SureScan defibrillation system is required for
use in the MR environment. A complete SureScan system
includes a Medtronic SureScan device with the appropriate
number of Medtronic SureScan leads.The Model 6947 lead is
part of the Medtronic SureScan defibrillation system. Labeling for
SureScan system components displays the SureScan logo and
the MR Conditional symbol. To verify that components are part of
a SureScan system, visit http://www.mrisurescan.com. Any other
combination may result in a hazard to the patient during an MRI
scan.
SureScan logo
MR Conditional symbol. The Medtronic SureScan system is MR Conditional and is designed to allow implanted patients to undergo an MRI scan under the specified MRI conditions for use.
The MRI SureScan feature permits a mode of operation that
allows a patient with a SureScan device to be safely scanned by
an MRI machine while the device continues to provide appropriate
pacing. When programmed to On, MRI SureScan operation
disables arrhythmia detection, magnet mode, and all
user-defined diagnostics. Before performing an MRI scan,
2
refer to the SureScan system MRI technical manual for
important information about procedures and MRI-specific
warnings and precautions.
1.2 Package contents
Leads and accessories are supplied sterile. Each package
contains the following items:
●
1 lead with 1 radiopaque anchoring sleeve, stylet, and stylet
guide
●
1 slit anchoring sleeve
●
1 vein lifter
●
2 fixation tools
●
2 pin caps
●
extra stylets
●
product literature
1
Tensi-Lock is an exclusive Medtronic design feature that utilizes lead body cables to act like a built-in locking stylet and add tensile strength to the lead.
2
IS-1 refers to the International Connector Standard ISO 5841-3, whereby pulse generators and leads so designated are assured of a basic mechanical fit.
3
DF-1 refers to the International Connector Standard ISO 11318, whereby pulse generators and leads so designated are assured of a basic mechanical fit.
3
1.3 Accessory descriptions
Dispose of all single-use accessories according to local
environmental requirements.
Anchoring sleeve – An anchoring sleeve secures the lead to
prevent it from moving and protects the lead insulation and
conductors from damage caused by tight sutures.
Fixation tool – A fixation tool facilitates connector pin rotation.
Pin cap – A pin cap covers and insulates unused connector pins.
Slit anchoring sleeve – A slit anchoring sleeve secures excess
lead length in the device pocket.
Stylet – A stylet provides additional stiffness and controlled
flexibility for maneuvering the lead into position. Each stylet knob
is labeled with the stylet diameter and corresponding lead length.
Stylet guide – A stylet guide facilitates stylet insertion into the
lead.
Vein lifter – A vein lifter facilitates lead insertion into a vein.
2 Indications
The lead is intended for single, long-term use in the right ventricle.
This lead has application for patients for whom implantable
cardioverter defibrillators (ICDs) are indicated.
3 Drug component description
The active ingredients in the 6947 lead are dexamethasone
acetate [21-(acetyloxy)-9-fluoro-11β,
17-trihydroxy-16α-methylpregna-1,4-diene-3,20-dione] and
dexamethasone sodium phosphate [9-fluoro-11β,
17-dihydroxy-16α-methyl-21-(phosphonooxy)
pregna-1,4-diene-3,20-diene-3,20-dione disodium salt].
The structural formula for each of these steroids is shown below:
Figure 1. Structural formula for dexamethasone sodium phosphate (DSP)
Dexamethasone sodium phosphate is an inorganic ester of
dexamethasone, a synthetic adrenocortical steroid.
Dexamethasone sodium phosphate is a white or slightly yellow
crystalline powder. It is freely soluble in water and is very
hygroscopic.
Figure 2. Structural formula for dexamethaxone acetate (DXAC)
Dexamethasone acetate is a white to practically white, odorless
powder. Dexamethasone acetate is a practically insoluble ester of
dexamethasone, a synthetic adrenocortical steroid.
The maximum dosage of dexamethasone sodium phosphate and
dexamethasone acetate is less than 1.0 mg per lead.
4 Contraindications
Before performing an MRI scan, refer to the SureScan
system MRI Technical Manual for MRI-specific
contraindications.
Atrial use – The lead is contraindicated for the sole use of
detection and treatment of atrial arrhythmias.
Ventricular use – The lead is contraindicated for ventricular use
in patients with tricuspid valvular disease or a tricuspid
mechanical heart valve.
Transient ventricular tachyarrhythmias – The lead is
contraindicated for patients with transient ventricular
tachyarrhythmias due to reversible causes (drug intoxication,
electrolyte imbalance, sepsis, hypoxia) or other factors
(myocardial infarction, electric shock).
Steroid use – The lead is contraindicated in patients for whom a
combined dose of 1.0 mg of dexamethasone sodium phosphate
and dexamethasone acetate may be contraindicated.
4
5 Warnings and precautions
A complete SureScan defibrillation system is required for
use in the MR environment. A complete SureScan
defibrillation system includes a SureScan device with the
appropriate number of SureScan leads. To verify that
components are part of a SureScan system, visit
http://mrisurescan.com. Any other combination may result in a
hazard to the patient during an MRI scan.
Single use – The lead and accessories are for single use only.
Inspecting the sterile package – Inspect the sterile package
with care before opening it.
●
If the seal or package is damaged, contact a Medtronic
representative.
●
Store at 25 °C (77 °F). Excursions from this storage
temperature are permitted in the range of 15 to 30 °C (59 to
86 °F). (See USP Controlled Room Temperature.) According
to USP excursion conditions, transient spikes up to 40 °C
(104 °F) are permitted as long as they do not exceed 24 hours.
●
Do not use the product after its expiration date.
Sterilization – Medtronic has sterilized the package contents
with ethylene oxide before shipment. This lead is for single use
only and is not intended to be resterilized.
Electrophysiologic testing – Prior to lead implant, it is strongly
recommended that patients undergo a complete cardiac
evaluation, which should include electrophysiologic testing. Also,
electrophysiologic evaluation and testing of the safety and
efficacy of the proposed pacing, cardioversion, or defibrillation
therapies are recommended during and after the implant of the
system.
Steroid use – It has not been determined whether the warnings,
precautions, or complications usually associated with injectable
dexamethasone sodium phosphate or dexamethasone acetate
apply to the use of this highly localized, controlled-release lead.
For a list of potentially adverse effects, refer to the Physicians’
Desk Reference.
Handling the steroid tip – Avoid reducing the amount of steroid
available before implanting the lead. Reducing the available
amount of steroid may adversely affect low-threshold
performance.
●
Do not allow the electrode surface to come in contact with
surface contaminants.
●
Do not wipe or immerse the electrode in fluid, except blood, at
the time of implant.
Handling the lead – Handle the lead with care at all times.
●
Protect the lead from materials shedding particles such as lint
and dust. Lead insulators attract these particles.
●
Handle the lead with sterile surgical gloves that have been
rinsed in sterile water or a comparable substance.
●
Do not severely bend, kink, or stretch the lead.
●
Do not use surgical instruments to grasp the lead or
connector pins.
●
Do not immerse the leads in mineral oil, silicone oil, or any
other liquid, except blood, at the time of implantation.
●
Do not implant the lead without first verifying the mechanical
functioning of the helix electrode. Refer to Section 9.2,
“Verifying the mechanical functioning of the helix electrode”,
page 9 for complete instructions.
●
Do not rotate the helix electrode after it is fully extended or fully
retracted. The number of rotations required to fully extend or
retract the helix electrode is variable. Furthermore, do not
exceed the recommended maximum number of rotations to
extend or retract the helix electrode. Exceeding the maximum
number may result in fracture or distortion of the inner
conductor or helix electrode. Refer to Section 10.1 for the
recommended maximum number of rotations.
●
Inserting the lead using a lead introducer that has a
hemostasis valve may require a larger introducer than the size
recommended. To avoid distortion of the coil electrode, do not
withdraw the lead through a hemostasis valve.
Handling the stylet – Handle the stylet with care at all times.
●
Do not use a sharp object to impart a curve to the distal end of
the stylet.
●
Do not use excessive force or surgical instruments when
inserting the stylet into the lead.
●
Avoid overbending or kinking the stylet.
●
Use a new stylet when blood or other fluids accumulate on the
stylet. Accumulated blood or other fluids may damage the
lead or cause difficulty in passing the stylet into the lead.
Necessary hospital equipment – Keep external defibrillation
equipment nearby for immediate use during acute lead system
testing, the implant procedure, or whenever arrhythmias are
possible or intentionally induced during post-implant testing.
Line-powered and battery-powered equipment – An
implanted lead forms a direct current path to the myocardium.
During lead implant and testing, use only battery-powered
equipment or line-powered equipment specifically designed for
this purpose to protect against fibrillation that may be caused by
alternating currents. Line-powered equipment used in the vicinity
of the patient must be properly grounded. Lead connector pins
must be insulated from any leakage currents that may arise from
line-powered equipment.
Concurrent devices – Output pulses, especially from unipolar
devices, may adversely affect device sensing capabilities. If a
patient requires a separate stimulation device, either permanent
or temporary, allow enough space between the leads of the
separate systems to avoid interference in the sensing capabilities
of the devices. Previously implanted pulse generators and
implantable cardioverter defibrillators should generally be
explanted.
Magnetic resonance imaging (MRI) – An MRI is a type of
medical imaging that uses magnetic fields to create an internal
view of the body. If certain criteria are met and the warnings and
precautions provided by Medtronic are followed, patients with an
MR Conditional device and lead system are able to undergo an
MRI scan; for details, refer to the SureScan MRI technical manual
that Medtronic provides for an MR Conditional device.
Diathermy treatment (including therapeutic ultrasound) –
Diathermy is a treatment that involves the therapeutic heating of
body tissues. Diathermy treatments include high frequency, short
wave, microwave, and therapeutic ultrasound. Except for
therapeutic ultrasound, do not use diathermy treatments on
cardiac device patients. Diathermy treatments may result in
serious injury or damage to an implanted device and lead system.
Therapeutic ultrasound (including physiotherapy, high intensity
therapeutic ultrasound, and high intensity focused ultrasound), is
the use of ultrasound at higher energies than diagnostic
ultrasound to bring heat or agitation into the body. Therapeutic
ultrasound is acceptable if treatment is performed with a minimum
5
separation distance of 15 cm (6 in) between the applicator and the
implanted device and lead system, as long as the ultrasonic beam
is pointing away from the device and lead system.
Chronic lead removal and the SureScan defibrillation
system – When implanting a SureScan defibrillation system,
consider the risks associated with removing previously implanted
leads before doing so. Abandoned leads or previously implanted
non-SureScan labeled leads compromise the ability to safely
scan the SureScan defibrillation system during MRI scans.
Chronic repositioning or removal of a screw-in lead –
Proceed with extreme caution if a lead must be removed or
repositioned. Chronic repositioning or removal of screw-in
transvenous leads may not be possible because of blood or
fibrotic tissue development into the helix mechanism on the lead.
In most clinical situations, it is preferable to abandon unused leads
in place. Return all removed leads, unused leads, or lead sections
to Medtronic for analysis.
Note: If a helix does not disengage from the endocardium by
rotating the connector pin, rotating the lead body
counterclockwise may withdraw the helix and decrease the
possibility of damage to cardiovascular structures during removal.
●
Lead removal may result in avulsion of the endocardium,
valve, or vein.
●
Lead junctions may separate, leaving the lead tip and bare
wire in the heart or vein.
●
Chronic repositioning of a lead may adversely affect the
low-threshold performance of a steroid lead.
●
An abandoned lead should be capped so that the lead does
not transmit electrical signals.
●
Severed leads should have the remaining lead end sealed
and the lead body sutured to adjacent tissue.
External defibrillation and cardioversion – External
defibrillation and cardioversion are therapies that deliver an
electrical shock to the heart to convert an abnormal heart rhythm
to a normal rhythm.
Medtronic cardiac devices are designed to withstand exposure to
external defibrillation and cardioversion. While damage to an
implanted system from an external shock is rare, the probability
increases with increased energy levels. These procedures may
also temporarily or permanently elevate pacing thresholds or
temporarily or permanently damage the myocardium. If external
defibrillation or cardioversion are required, consider the following
precautions:
●
Use the lowest clinically appropriate energy.
●
Position the patches or paddles no closer than 15 cm (6 in) to
the device.
●
Position the patches or paddles perpendicular to the device
and lead system.
●
If an external defibrillation or cardioversion is delivered within
15 cm (6 in) of the device, use a Medtronic programmer to
evaluate the device and lead system.
6 Drug information
Steroid mechanism of action – Steroid suppresses the
inflammatory response that is believed to cause threshold rises
typically associated with implanted pacing electrodes.
Dexamethasone sodium phosphate and dexamethasone acetate
are synthetic steroids of the glucocorticoid family. Glucocorticoids
have potent anti-inflammatory actions via direct and indirect
effects on major inflammatory cells. Glucocorticosteroids bind to
a cytoplasmic glucocorticoid receptor as well as a
membrane-bound receptor. Binding to the cytoplasmic receptor
leads to receptor activation and translocation to the nucleus. The
receptor interacts with specific DNA sequences within the
regulatory regions of affected genes. Thus, glucocorticoids inhibit
the production of multiple cell factors that are critical in generating
the inflammatory response.
7 Pharmacodynamics of the Model 6947 lead
Pharmacokinetics – The pharmacokinetics (local drug levels
and systemic levels) of dexamethasone acetate (DXAC) and
dexamethasone sodium phosphate (DSP) and their metabolites
following lead implantation were not evaluated in human clinical
trials.
The in-vivo elution profile of a tined pacemaker lead with a DSP
monolithic controlled release device, based upon an assay of
explanted leads, is shown in Mond and Stokes4.
Metabolism – The conversion of DSP to dexamethasone occurs
within minutes; the conversion of DXAC to dexamethasone
occurs within hours. The dexamethasone alcohol
(dexamethasone) is the active glucocorticoid used in Medtronic
leads. Steroid is applied to the tip and eluted through the electrode
tip to the tissue interface where it will be used. Dexamethasone
acetate and Dexamethasone sodium phosphate are hydrolyzed
into dexamethasone, which is readily absorbed by the
surrounding tissue and body fluids. Glucocorticoids, when given
systemically, are eliminated primarily by renal excretion of inactive
metabolites.
Mutagenesis, carcinogenicity and reproductive toxicology –
The mutagenesis, carcinogenicity, and reproductive toxicity of the
Model 6947 lead have not been evaluated. However, the
mutagenesis, carcinogenicity, and reproductive toxicity of
dexamethasone acetate and dexamethasone sodium phosphate
have been evaluated previously.
Carcinogenesis, mutagenesis, impairment of fertility – No
adequate studies have been conducted in animals to determine
whether corticosteroid have a potential for carcinogenesis (tumor
initiation or promotion). Dexamethasone was genotoxic in assays
for clastogenicity (including sister chromatid exchange in human
lymphocytes) but not in an assay for mutagenicity in salmonella
(Ames test).
Adrenocorticoids have been reported to increase or decrease the
number and mobility of spermatozoa in some patients.
4
Mond, H. and Stokes, K.B., The Electrode - Tissue Interface: The Revolutionary Role of Steroid Elution, Pacing and Clinical Electrophysiology, Vol. 15, No. 1, pp
95-107
6
Pregnancy – Pregnancy category C. Dexamethasone acetate
and Dexamethasone sodium phosphate have been shown to be
teratogenic in many species when given in doses equivalent to the
human dose. There are no adequate and well-controlled studies
in pregnant women. Dexamethasone acetate and
Dexamethasone sodium phosphate should be used during
pregnancy only if the potential benefit justifies the potential risk to
the fetus. Studies in mice, rats, and rabbits have shown that
adrenocorticoids increase the incidence of cleft palate, placental
insufficiency, and spontaneous abortions, and can decrease the
intrauterine growth rate.
Nursing mothers – Systemically administered corticosteroids
appear in human milk and could suppress growth, interfere with
endogenous corticosteroid production, or cause other untoward
effects in nursing infants. Because of the potential for serious
adverse reactions in nursing infants from corticosteroids, a
decision should be made whether to discontinue nursing or to use
a non-steroidal lead, taking into account the importance of the
lead and the drug to the mother.
8 Adverse events and clinical trial data
Observed adverse events – The Model 6947 Lead was utilized
in a prospective, nonrandomized, multicenter trial to assess the
handling and performance of the Sprint Quattro Secure Model
6947 Lead.
A total of 22 cardiovascular-related adverse events were reported.
Two of the 22 events were ventricular lead-related and both
occurred at implant. One event was a microdislodgement and one
was induced VT as a result of lead manipulation.
Two deaths occurred in this patient group during the follow-up
period. Both deaths were classified as non-sudden cardiac and
were judged to be non-system related by an independent advisory
committee.
Information regarding clinical studies and adverse events related
to this lead is available at www.medtronic.com/manuals. The
following clinical studies are related to this lead:
●
Model 6932 RV Lead clinical study
●
Model 6947 RV Lead clinical study
●
Evera MRI System study – This clinical study was executed to
confirm safety and efficacy of the Evera MRI system in the
clinical MRI environment when subjects receive MRI scans up
to 2 W/kg SAR without positioning restrictions (MRI scans
may occur anywhere on the body), providing support for the
Sprint Quattro Secure Model 6947 device.
If you do not have web access, a printed copy of the related clinical
study summary can be obtained from your Medtronic
representative, or you can call the toll-free number located on the
back cover.
Potential adverse events – The potential adverse events
associated with the use of transvenous leads and pacing systems
include, but are not limited to, the following events:
●
acceleration of tachyarrhythmias (caused by device)
●
air embolism
●
bleeding
●
body rejection phenomena, including local tissue reaction
●
cardiac dissection
●
cardiac perforation
●
cardiac tamponade
●
chronic nerve damage
●
constrictive pericarditis
●
death
●
device migration
●
endocarditis
●
erosion
●
excessive fibrotic tissue growth
●
extrusion
●
fibrillation or other arrhythmias
●
fluid accumulation
●
formation of hematomas/seromas or cysts
●
heart block
●
heart wall or vein wall rupture
●
hemothorax
●
infection
●
keloid formation
●
lead abrasion and discontinuity
●
lead migration/dislodgement
●
mortality due to inability to deliver therapy
●
muscle and/or nerve stimulation
●
myocardial damage
●
myocardial irritability
●
myopotential sensing
●
pericardial effusion
●
pericardial rub
●
pneumothorax
●
poor connection of the lead to the device, which may lead to
oversensing, undersensing, or a loss of therapy
●
threshold elevation
●
thrombosis
●
thrombotic embolism
●
tissue necrosis
●
valve damage (particularly in fragile hearts)
●
venous occlusion
●
venous perforation
Other potential adverse events related to the lead include, but are
not limited to, the following conditions:
●
insulation failure
●
lead conductor or electrode fracture
●
lead dislodgement
●
poor connection to the device, which may lead to
oversensing, undersensing, or a loss of therapy
The Model 6947 clinical study was a prospective,
nonrandomized, multicenter trial assessing the lead handling and
performance of the Sprint Quattro Secure Model 6947 Lead.
The Model 6947 lead was implanted in 80 patients at 15
investigative centers in the United States and at 2 investigative
centers in Canada between April 27, 2001 and August 2, 2001.
7
Patients were included in this study if they met the following
criteria: 1) able to receive a pectoral implant and 2) survived at
least one episode of cardiac arrest due to a ventricular
tachyarrhythmia; or had poorly tolerated, sustained ventricular
tachycardia that occurred spontaneously; or had poorly tolerated,
sustained ventricular tachycardia that could be induced.
Patients studied – The Model 6947 study population consisted
of 63 males and 17 females. The mean age was 64.4 years. The
most frequently reported indication for implant was inducible
ventricular tachycardia without sudden cardiac death (SCD)
(47.5%). The mean ejection fraction was 35.5%. The most
frequently reported NYHA classifications were Class I (35.0%)
and Class II (36.3%).
Cardiovascular history included coronary artery disease with
myocardial infarction (62.5%), hypertension (58.8%),
cardiomyopathy (65.0%), congestive heart failure (47.5%),
syncope/presyncope (46.3%) and previous cardiac surgery
(68.8%).
Objectives – The objectives of the study were to report the
following:
●
Pacing thresholds
●
R-wave amplitudes
●
Pacing impedance
●
Lead handling
●
Adverse events
Methods – Pulse width thresholds, R-wave amplitudes, and
pacing impedances were measured at implant and at one month
post-implant. Adverse events were collected throughout the
study. A lead handling questionnaire was completed by the
implanting physician at each implant. The implanting physicians
evaluated the performance of the Model 6947 lead with regard to:
●
Ease of lead insertion into the vein
●
Ease of helix extension
●
Visibility of helix extension
●
Steerability
●
Torqueability
●
Lead placement time
●
Ability to traverse the tricuspid annulus
●
Comfort level with handling the lead
●
Slipperiness of lead surfaces
●
Stiffness of the lead
●
Ease of obtaining adequate R-wave sensing
●
Ease of obtaining adequate VF sensing
●
Ease of obtaining adequate DFTs
●
Overall ease of lead placement
Results – The mean follow-up duration was 0.96 months
(range: 0.00 – 1.71 months) with a cumulative follow-up duration
of 76.82 months. The pace/sense measurements are
summarized in Table 1.
Table 1. Pace/Sense measurements
Implant One month
Pulse-width threshold at one volt
N 80 61
Median 0.20 ms 0.20 ms
25th – 75th Percentile (0.20 – 0.20) (0.20 – 0.30)
Range (0.03 – 0.60) (0.20 – 0.80)
R-wave amplitude (EGM)
N 78 64
Median 8.0 mV 9.3 mV
25th – 75th Percentile (7.0 – 11.0) (7.5 – 12.8)
Range (3.0 – 24.0) (3.5 – 20.0)
Pacing lead impedance
N 80 66
Median 564.0 Ω 481.0 Ω
25th – 75th Percentile (481.0 – 611.0) (444.0 – 521.0)
Range (378.0 – 985.0) (323.0 – 985.0)
On the lead handling survey, for all items rated, the adjusted rating
of the Model 6947 lead fell between 1 (very good) and 2
(excellent). The adjusted rating for each item is an average across
physicians, accounting for multiple responses per physician.
The overall ease of lead placement was considered good, very
good, or excellent by all implanting physicians, with an adjusted
rating of 1.7 (the minimum rating on the questionnaire was –2.0
and the maximum rating was 2.0).
Conclusion – In this clinical study, the Model 6947 lead
demonstrated acceptable clinical performance. Through
questionnaire responses, implanting physicians verified
acceptable overall lead performance and handling during the
implant procedure.
9 Implant procedure
Warning: Before implanting a SureScan system, consider the
risks associated with removing previously implanted leads.
Abandoned leads or previously implanted leads not tested for MRI
compatibility compromise the ability to safely scan the SureScan
system during MRI scans.
Proper surgical procedures and sterile techniques are the
responsibility of the medical professional. The following
procedures are provided for information only. Some implant
techniques vary according to physician preference and the
patient’s anatomy or physical condition. Each physician must
apply the information in these instructions according to
professional medical training and experience.
8
9.1 Opening the package
Use the following steps to open the sterile package and inspect
the lead:
1. Within the sterile field, open the sterile package and remove
the lead and accessories.
2. Inspect the lead to verify that there is an anchoring sleeve on
the lead body.
9.2 Verifying the mechanical functioning of the helix electrode
Before implantation, verify the mechanical functioning of the helix
electrode:
1. With a stylet inserted into the lead, press both legs of the
fixation tool together and place the most distal hole of the
fixation tool on the connector pin (Figure 3).
Note: The stylet guide may be removed by gently pulling it
off. To reattach a stylet guide, gently push it onto the
connector pin.
Figure 3.
2. Hold the IS-1 connector leg of the lead with the thumb on one
side and four fingers on the other side. Keep the lead body
and the IS-1 connector leg as straight as possible (Figure 3).
Ensure that the stylet is fully inserted, then rotate the fixation
tool clockwise until the helix electrode is fully extended.
When the helix electrode is fully extended, approximately 1.5
to 2 helix coils are exposed.
Caution: Do not severely bend the IS-1 connector leg or the
lead body while extending the helix electrode (Figure 4). If
the lead is bent on either side of the lead trifurcation during
helix electrode extension or retraction, the lead may be
damaged.
Figure 4.
Caution: Over-rotating the connector pin after the helix
electrode is fully extended or fully retracted may damage the
lead. The number of rotations required to extend or retract
the helix electrode increases proportionately with the length
of the lead. Additional curvatures made to the stylet may
increase the number of rotations needed to extend or retract
the helix electrode. Rotation of the fixation tool should be
stopped once full helix retraction is visually verified.
Over-retraction of the helix may result in the inability to
extend the helix. If the helix is unable to extend, use a new
lead.
During the initial helix electrode extension, the helix
electrode may extend suddenly due to accumulated torque
in the lead, or the helix electrode may require additional turns
for extension.
3. Disconnect the fixation tool from the connector pin and
release the proximal end of the lead body. Allow several
seconds for relief of the residual torque in the lead.
4. After allowing for relief of the residual torque, reattach the
fixation tool and rotate it counterclockwise until the helix
electrode tip is retracted into the sheath.
9.3 Inserting the lead
Caution: Use care when handling the lead during insertion.
●
Do not severely bend, kink, or stretch the lead.
●
Do not use surgical instruments to grasp the lead or
connector pins.
Insert the lead using the following techniques:
1. Select a site for lead insertion. The lead may be inserted by
venotomy through several different venous routes, including
the right or left cephalic vein, the subclavian vein, or the
external or internal jugular vein. Use the cephalic vein
whenever possible to avoid lead damage in the first rib or
clavicular (thoracic inlet) space.
9
Cautions:
1
●
Certain anatomical abnormalities, such as thoracic
outlet syndrome, may also precipitate pinching and
subsequent fracture of the lead.
●
When using a subclavian approach, avoid techniques
that may damage the lead.
●
Place the insertion site as far lateral as possible to avoid
clamping the lead body between the clavicle and the first
rib (Figure 5).
Figure 5.
1 Suggested entry site
●
Do not force the lead if significant resistance is
encountered during lead passage.
●
Do not use techniques such as adjusting the patient’s
posture to facilitate lead passage. If resistance is
encountered, it is recommended that an alternate
venous entry site be used.
2. Insert the tapered end of a vein lifter into the incised vein and
gently push the lead tip underneath and into the vein
(Figure 6).
Note: A percutaneous lead introducer (PLI) kit may be used
to facilitate insertion. Refer to the technical manual packaged
with an appropriate percutaneous lead introducer for further
instructions.
Figure 6.
3. Advance the lead into the right atrium using a straight stylet to
facilitate movement through the veins.
9.4 Positioning a screw-in ventricular lead
Caution: Use care when handling the lead during positioning.
●
Do not severely bend, kink, or stretch the lead.
●
Do not use surgical instruments to grasp the lead or
connector pins.
Use the following steps to position the lead:
1. After the lead tip is passed into the atrium, advance the lead
through the tricuspid valve. Replace the straight stylet with a
gently curved stylet to add control when maneuvering the
lead through the tricuspid valve.
Caution: Do not use a sharp object to impart a curve to the
distal end of the stylet. Imparting a curve to the stylet can be
accomplished with a smooth-surface, sterile instrument
(Figure 7).
Figure 7.
Note: When you pass the lead tip through the tricuspid valve
or chordae tendineae, it may be difficult due to the flexible
nature of the lead body. Rotate the lead body as the tip
passes through the valve to facilitate passage.
2. After the lead tip is in the ventricle, the curved stylet may be
replaced with a straight stylet. Withdraw the stylet slightly, to
avoid using excessive tip force while achieving final
electrode position. Avoid known infarcted or thin wall areas to
minimize the occurrence of perforation.
3. Proper positioning of the helix electrode is essential for
stable endocardial pacing. A satisfactory position usually is
achieved when the lead tip points straight toward the apex, or
when the distal end dips or bends slightly. Use fluoroscopy
(lateral position) to ensure that the tip is not in a retrograde
position or lodged in the coronary sinus.
Note: With the helix electrode retracted, the distal end of the
lead may be used to map a desirable site for electrode
fixation. Mapping may reduce the need to repeatedly extend
and fixate the helix electrode.
4. After placing the lead in a satisfactory position, extend the
helix electrode by following the procedure in Section 9.5.
9.5 Securing the helix electrode into the endocardium
Secure the helix electrode using the following techniques:
1. Press both legs of the fixation tool together and place the
most distal hole on the IS-1 connector pin (Step 1).
10
2. Press the lead tip against the endocardium by gently pushing
A B
AB
the stylet and lead at the vein entry site.
3. Rotate the fixation tool clockwise until the helix electrode is
fully extended.
Caution: Do not severely bend the IS-1 connector leg or the
lead body while extending the helix electrode. If the lead is
bent on either side of the lead trifurcation during helix
electrode extension or retraction, the lead may be damaged.
Use fluoroscopy to verify helix electrode extension. The
fluoroscope head may need to be rotated to obtain an
adequate view. Both a visual and fluoroscopic view of a fully
retracted and extended helix electrode is shown in Figure 8.
Closing of the space between the indicator stop (A) and the
indicator ring (B) implies complete extension of the helix
electrode.
Figure 8.
1 Fully retracted visual
2 Fully retracted fluoroscopic
3 Fully extended visual
4 Fully extended fluoroscopic
Cautions:
●
The number of rotations required to fully extend or retract
the helix electrode is variable. Rotation should be
stopped once full helix extension or retraction is verified
with fluoroscopy as shown in Figure 8. Over-retraction of
the helix, during initial implant or subsequent
repositioning, may result in the inability to extend the
helix. If the helix is unable to extend, replace with a new
lead.
●
Do not exceed the recommended maximum number of
rotations to extend or retract the helix electrode.
Exceeding the maximum number may result in fracture
or distortion of the inner conductor or helix electrode.
Refer to Chapter 10 for the recommended maximum
number of rotations.
●
Prolonged implant procedures or multiple repositionings
may allow blood or body fluids to build up on the helix
electrode mechanism. This may result in an increased
number of rotations required to extend or retract the
helix electrode.
4. Remove the fixation tool from the IS-1 connector pin, and
release the proximal end of the lead body. Allow several
seconds for relief of the residual torque in the lead.
5. To assure helix electrode fixation, leave the stylet in place,
hold the lead by the connector, and carefully rotate the lead
body in 2 clockwise rotations.
6. Partially withdraw the stylet.
7. Obtain electrical measurements to verify satisfactory
placement and electrode fixation. Refer to Section 9.6,
“Taking electrical measurements and defibrillation efficacy
measurements”, page 11.
8. Verify that the lead is affixed. Gently pull back on the lead,
and check for resistance to verify fixation. A properly affixed
helix electrode will remain in position. If the helix electrode is
not properly affixed, the lead tip may become loose in the
right ventricle.
9. If repositioning is required, reattach the fixation tool, and
rotate counterclockwise until the helix electrode is retracted.
Use fluoroscopy to verify withdrawal of the helix electrode
before attempting to reposition.
10. After final positioning, make sure that the stylet, stylet guide,
and fixation tool have been completely removed. When
removing the stylet guide, grip the lead firmly just below the
connector pin to help prevent lead dislodgement.
11. Obtain final electrical measurements. Refer to Section 9.6.
9.6 Taking electrical measurements and defibrillation efficacy measurements
Caution: Prior to taking electrical or defibrillation efficacy
measurements, move objects made from conductive materials,
such as guide wires, away from all electrodes. Metal objects, such
as guide wires, can short a lead and an active implantable device,
causing electrical current to bypass the heart and possibly
damage the implantable device and lead.
Use the following steps to take electrical measurements:
1. Attach a surgical cable to the lead connector pin. A notch in
the stylet guide allows connection of a surgical cable for
obtaining electrical measurements.
2. Use a testing device, such as a pacing system analyzer, for
obtaining electrical measurements. For information about
the use of the testing device, consult the product
documentation for that device.
In order to demonstrate reliable defibrillation efficacy, obtain final
defibrillation measurements for the lead system.
Table 2. Recommended measurements at implant (when using a pacing system analyzer)
Measurements
required Acutea lead system
Capture threshold
(at 0.5 ms pulse width)
Pacing impedance 200–1000 Ω 200–1000 Ω
≤1.0 V ≤3.0 V
Chronicb lead sys-
tem
11
Table 2. Recommended measurements at implant
(when using a pacing system analyzer) (continued)
Measurements
required Acutea lead system
Filtered R-wave
amplitude (during
sinus rhythm)
Slew rate ≥0.75 V/s ≥0.45 V/s
a
≤30 days after implant.
b
>30 days after implant.
≥5 mV ≥3 mV
Chronicb lead sys-
tem
If pacing thresholds and R-wave amplitudes do not stabilize to
acceptable levels, it may be necessary to reposition the lead and
repeat the testing procedure.
Values may vary depending upon implantable device settings,
cardiac tissue condition, and drug interactions.
Warning: If the implanted lead system fails to terminate a VF
episode, rescue the patient promptly with an external defibrillator .
At least 5 min should elapse between VF inductions.
For more information about obtaining electrical measurements,
consult the product documentation supplied with the testing
device.
9.7 Anchoring the lead
Caution: Use care when anchoring the lead.
●
Use only nonabsorbable sutures to anchor the lead.
●
Do not attempt to remove or cut the anchoring sleeve from the
lead body.
●
During lead anchoring, take care to avoid dislodging the
lead tip.
●
Do not secure sutures so tightly that they damage the vein,
lead, or anchoring sleeve (Figure 9).
●
Do not tie a suture directly to the lead body (Figure 9).
Figure 9.
Figure 10.
3. Use at least one additional suture in one of the grooves to
secure the anchoring sleeve and lead body to the fascia.
4. A slit anchoring sleeve may be used in the device pocket to
secure excess lead length. First, secure the anchoring
sleeve to the lead body. Then, orient the slit toward the fascia
and secure the anchoring sleeve to the fascia with sutures.
9.8 Connecting the lead
Use the following steps to connect the lead to an implantable
device:
1. Make sure that the stylet and all accessories have been
completely removed. When removing the accessories, grip
the lead firmly just below the connector pin to prevent
dislodgement.
2. Insert the lead connectors into the connector block. Consult
the product documentation packaged with the implantable
device for instructions on proper lead connections.
9.9 Placing the device and lead into the pocket
Caution: Use care when placing the device and leads into
the pocket.
●
Ensure that the leads do not leave the device at an acute
angle.
●
Do not grip the lead or device with surgical instruments.
●
Do not coil the lead. Coiling the lead can twist the lead body
and may result in lead dislodgement (Figure 11).
Figure 11.
Use the following steps to anchor the lead using all 3 grooves:
Note: The anchoring sleeve contains a radiopaque substance,
which allows visualization of the anchoring sleeve on a standard
x-ray and may aid in follow-up examinations.
1. Position the distal anchoring sleeve against or near the vein.
2. Secure the anchoring sleeve to the lead body by tying a
suture firmly in each of the 3 grooves (Figure 10).
12
Use the following steps to place the device and leads into the
pocket:
1. To prevent undesirable twisting of the lead body, rotate the
device to loosely wrap the excess lead length (Figure 12).
Figure 12.
2. Insert the device and leads into the pocket.
3. Before closing the pocket, verify sensing, pacing,
cardioversion, and defibrillation efficacy.
9.10 Post-implant evaluation
After implant, monitor the patient’s electrocardiogram until the
patient is discharged. If a lead dislodges, it typically occurs shortly
after implant.
Recommendations for verifying proper lead positioning include
x-rays and pacing and sensing threshold measurements.
In the event of a patient death, explant all implanted leads and
devices and return them to Medtronic with a completed Product
Information Report form. Call the appropriate phone number on
the back cover if there are any questions on product handling
procedures.
10 Specifications (nominal)
10.1 Detailed device description
Table 3. Specifications (nominal)
Parameter Model 6947
Type Quadripolar
Position Right ventricle
Fixation Extendable/retractable helix
Length 58 cm, 65 cm
Connector Unipolar (2) DF-1
Bipolar IS-1
Materials Conductors: MP35N coil
MP35N composite cables
Insulation: Silicone, PTFE, ETFE
Overlay: Polyurethane
Electrodes (pace, sense): Platinized platinum alloy
RV/SVC coils: Platinum-clad tantalum
DF-1 pins: Stainless steel
IS-1 pin and ring: Stainless steel
Steroid Type: Dexamethasone acetate
Dexamethasone sodium phosphate
Amount: 685 µg dexamethasone acetate
59 µg dexamethasone sodium
phosphate
Steroid binder: Silicone
Table 3. Specifications (nominal) (continued)
Parameter Model 6947
Conductor
resistances
Helix length (extended) 1.8 mm
Diameters Lead body: 2.8 mm
Lead introducer (recommended
size)
Pacing (unipolar): 29 Ω (65 cm)
Pacing (bipolar): 32.3 Ω (65 cm)
Defibrillation: <1.2 Ω (65 cm)
Tip: 2.8 mm
Helix: 1.4 mm
without guide wire: 3.0 mm (9.0 French)
with guide wire: 3.7 mm (11.0 French)
Table 4. Maximum number of rotations to extend or retract the helix electrode
Lead length Number of rotations
58 cm 18
65 cm 20
Table 5. Respective electrode distances
Helix electrode to ring electrode 8 mm
Helix electrode to RV coil electrode 12 mm
Helix electrode to SVC coil electrode 180 mm
13
Figure 13. Model 6947 distal lead components
1
234
5
Figure 14. Model 6947 proximal lead components
1 Helix electrode; surface area: 5.7 mm
2 Ring electrode; surface area: 25.2 mm
3 RV coil electrode; length: 57 mm; surface area: 614 mm2; electrical
shadow area: 506 mm
4 SVC coil electrode; length: 80 mm; surface area: 860 mm2; electrical
shadow area: 709 mm
5 Anchoring sleeve
14
2
2
2
2
1 DF-1 Connector (red band); Connector pin is common to RV coil
electrode
2 DF-1 Connector (blue band); Connector pin is common to SVC coil
electrode
3 IS-1 BI contact; Connector pin is common to tip electrode; connector
ring is common to ring electrode
11 Medtronic warranty
For complete warranty information, see the accompanying
warranty document.
12 Service
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. Medtronic also maintains a professional staff
to provide technical consultation to product users. For more
information, contact your local Medtronic representative, or call or
write Medtronic at the appropriate telephone number or address
listed on the back cover.
Medtronic, Inc.
*M965526A001*
710 Medtronic Parkway
Minneapolis, MN 55432
USA
www.medtronic.com
+1 763 514 4000
Medtronic USA, Inc.
Toll-free in the USA (24-hour technical consultation for
physicians and medical professionals)
Bradycardia: +1 800 505 4636
Tachycardia: +1 800 723 4636
Europe/Middle East/Africa
Medtronic International Trading Sàrl
Route du Molliau 31
Case Postale 84
CH-1131 Tolochenaz
Switzerland
+41 21 802 7000
Technical manuals
www.medtronic.com/manuals
© 2016 Medtronic
M965526A001 B
2016-03-10
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