SPRINT FIDELIS™ 6948
A02224001C_view.pdf
Steroid eluting, quadripolar, ventricular lead with tined
tip and RV/SVC defibrillation coil electrodes
Technical manual
Caution: Federal Law (USA) restricts this
device to sale by or on the order of a
physician (or properly licensed
practitioner).
The following are trademarks of Medtronic: Medtronic, Sprint
Fidelis, Sprint Quattro, CapSure Sense
Table of Contents
Device description 5
Contents of package 6
Accessory descriptions 6
Indications 6
Contraindications 6
Warnings and precautions 7
Potential adverse events 10
Clinical study 10
Model 6944 clinical study 11
Model 4074 (CapSure Sense tip electrode) clinical study 15
Directions for use 20
Opening the package 21
Inserting the lead 21
Positioning the lead 22
Taking electrical measurements and defibrillation efficacy
measurements 23
Anchoring the lead 24
Connecting the lead 25
Placing the device and leads into the pocket 26
Post-implant evaluation 26
Detailed device description 27
Specifications (nominal) 27
Specifications drawing (nominal) 28
Medtronic warranty 29
Service 29
6948 Technical manual 3
Device description
The Medtronic Sprint Fidelis Model 6948 lead is a steroid eluting,
quadripolar, ventricular lead with tined tip and right ventricular (RV)
and superior vena cava (SVC) defibrillation coil electrodes. The lead
is designed for pacing, sensing, cardioversion, and defibrillation
therapies.
The lead features a tined tip, silicone insulation with overlay, parallel
conductors, titanium nitride coated platinum iridium tip and ring
electrodes, and RV and SVC coil electrodes. See “Specifications
drawing (nominal)” on page 28 for a lead drawing.
■
The tip electrode is common to the connector pin of the
1
bipolar leg.
IS-1
■
The ring electrode is common to the connector ring of the
1
bipolar leg.
IS-1
■
The RV coil electrode is common to the DF-12 leg of the
trifurcation, labeled and marked with a red band.
■
The SVC coil electrode is common to the DF-12 leg of the
trifurcation, labeled and marked with a blue band.
The RV and SVC coils deliver cardioversion and defibrillation
therapies. Pacing and sensing occur between the tip and ring
electrodes.
The IS-1 bipolar leg of the trifurcation features a lumen for stylet
passage. The DF-1 connectors will not accept a stylet.
The steroid dexamethasone sodium phosphate is located on the tip
electrode surface. The tip electrode also incorporates a steroid
eluting plug containing dexamethasone acetate. The tip electrode
contains a maximum of 1.0 mg of dexamethasone steroid. Exposure
to body fluids elutes the steroid from the lead tip. The steroid is known
to suppress the inflammatory response that is believed to cause
threshold rises typically associated with implanted pacing electrodes.
1
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.
2
DF-1 refers to the International Connector Standard (ISO 11318) whereby
pulse generators and leads so designated are assured of a basic
mechanical fit.
6948 Technical manual English 5
Contents of package
The lead and accessories are provided sterile. Each package
contains the following:
■
1 lead with 1 radiopaque anchoring sleeve1, stylet, and stylet
guide
■
1 vein lifter
■
1 slit anchoring sleeve
■
2 pin caps
■
extra stylets
■
product literature
Accessory descriptions
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 length.
Stylet guide – A stylet guide facilitates stylet insertion into the lead.
Anchoring sleeve – An anchoring sleeve secures the lead from
moving and protects the lead insulation and conductors from damage
caused by tight sutures.
Slit anchoring sleeve – A slit anchoring sleeve secures excess lead
length in the device pocket.
Pin cap – A pin cap covers and insulates unused connector pins.
Vein lifter – A vein lifter facilitates lead insertion into a vessel.
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 are indicated.
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
single dose of 1.0 mg of dexamethasone may be contraindicated.
1
Two anchoring sleeves are provided with leads 85 cm or longer.
6 English 6948 Technical manual
Warnings and precautions
For single use only – Do not resterilize and reimplant an
explanted lead.
Inspecting the sterile package – Inspect the package prior
to opening.
■
If the seal or package is damaged, contact your local
Medtronic representative.
■
Do not use the product after its expiration date.
Ethylene oxide resterilization – The lead has been sterilized with
ethylene oxide prior to shipment. If the integrity of the sterile package
has been compromised prior to the expiration date, resterilize using
ethylene oxide. Avoid resterilization techniques that could damage
the lead.
■
Refer to sterilizer instructions for operating instructions.
■
Use an acceptable method for determining sterilizer
effectiveness, such as biological indicators.
■
Before resterilization, remove the disk tip protector, and place
the device in an ethylene oxide permeable package.
■
Do not exceed temperatures of 55°C (131°F).
■
Do not resterilize more than 1 time.
■
After resterilization, allow the device to aerate ethylene
oxide residues.
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 apply to the use of this highly localized,
controlled-release device. For listing of potentially adverse effects,
refer to the Physician’s Desk Reference.
Handling the steroid tip – Reducing the available amount of steroid
may adversely affect low-threshold performance. Avoid reducing the
amount of steroid available prior to lead implant.
■
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 great 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.
6948 Technical manual English 7
■
Do not severely bend, kink, or stretch the lead.
■
Do not use surgical instruments to grasp the lead or
connector pins.
■
Do not immerse leads in mineral oil, silicone oil, or any other
liquid, except blood, at the time of implant.
■
Inserting the lead using a lead introducer that features 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 stylets – Use care when handling stylets.
■
Do not use excessive force or surgical instruments when
inserting a stylet.
■
Avoid overbending and kinking.
■
Use a new stylet when blood or other fluids accumulate on the
stylet. Accumulated fluids may cause lead damage or difficulty
in passing the stylet through the lead.
■
Do not use a sharp object to impart a curve to the distal end of
the stylet.
Necessary hospital equipment – Keep external defibrillation
equipment nearby for immediate use during the acute lead system
testing, implant procedure, or whenever arrhythmias are possible or
intentionally induced during post-implant testing.
Line-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.
Second anchoring sleeve – Leads 85 cm or longer feature
2 anchoring sleeves. Use both anchoring sleeves to assure adequate
fixation, see the section “Anchoring the lead” on page 24.
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, implantable
cardioverter defibrillators, and leads should generally be explanted.
Refer to “Chronic repositioning or removal” on page 9, for further
information on explanting leads.
8 English 6948 Technical manual
Diathermy – People with metal implants such as pacemakers,
implantable cardioverter defibrillators (ICDs), and accompanying
leads should not receive diathermy treatment. The interaction
between the implant and diathermy can cause tissue damage,
fibrillation, or damage to the device components, which could result
in serious injury, loss of therapy, or the need to reprogram or replace
the device.
Chronic repositioning or removal – Chronic repositioning or
removal of leads may be difficult because of fibrotic tissue
development. Return all removed leads, or lead segments, to
Medtronic. If a lead must be removed or repositioned, proceed with
extreme caution.
■
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 may adversely affect the low-threshold
performance of a steroid eluting lead.
■
Cap abandoned leads to avoid transmitting electrical signals.
■
For leads that have been severed, seal the remaining lead end
and suture the lead to adjacent tissue.
Connector compatibility – Although the lead conforms to the
International Connector Standards IS-1 and DF-1, do not attempt to
use the lead with any device other than a commercially available
implantable defibrillator system with which it has been tested and
demonstrated to be safe and effective. The potential adverse
consequences of using such a combination may include, but are not
limited to, undersensing cardiac activity and failure to deliver
necessary therapy.
6948 Technical manual English 9
Potential adverse events
The potential adverse events related to the use of transvenous leads
include, but are not limited to, the following patient-related conditions:
■
cardiac perforation
■
cardiac tamponade
■
constrictive pericarditis
■
embolism
■
endocarditis
■
fibrillation or other arrhythmias
■
heart wall rupture
■
hemothorax
■
infection
■
pneumothorax
■
thrombosis
■
tissue necrosis
Other potential adverse events related to the lead include, but are not
limited to, the following:
■
Insulation failure
■
Lead conductor or electrode fracture
■
Lead dislodgment
■
Poor connection to the device, which may lead to oversensing,
undersensing, or a loss of therapy
Clinical study
Clinical data was not collected in the approval process for this lead.
Clinical data from the Models 6944 and 4074 leads support the safety
and efficacy of the Model 6948 lead.
The Model 6948 lead is a downsized version of the Medtronic Sprint
Quattro Model 6944 lead. The Model 6948 lead includes a
combination of components used in currently marketed Medtronic
leads with some enhancements. All functional features of the Model
6948 lead have been approved in these currently marketed Medtronic
leads. Previous clinical studies have shown titanium nitride coated
electrodes (6948) do not significantly change clinical pacing
thresholds or sensing amplitudes as compared to platinized
electrodes (6944 and 4074). The overall surface of the defibrillation
electrodes falls within the range of currently approved Sprint leads.
Based upon its similarity to the Model 6944 and 4074 leads, the
clinical data from these lead models supports the safety and efficacy
of the Model 6948 lead (Table 1).
10 English 6948 Technical manual
Tab le 1.
Sprint Fidelis Model 6948
features:
RV/SVC defibrillation electrodes RV/SVC defibrillation
Passive fixation - tines Passive fixation - tines
Ring electrode for true bipolar
sensing
Steroid eluting Steroid eluting
Silicone insulation with
polyurethane overlay
a
Standard
Sprint Fidelis Model 6948
features:
CapSure Sense electrode tip CapSure Sense electrode tip
a
electrode spacing
8 mm tip to ring spacing, 12 mm tip to RV coil spacing
Sprint Quattro Model 6944
clinical data supports:
electrodes
Ring electrode for true bipolar
sensing
Silicone insulation with
polyurethane overlay
a
Standard
CapSure Sense Model 4074
clinical data supports:
electrode spacing
Model 6944 clinical study
Note: The leads used for the Model 6944 clinical study contained
only dexamethasone acetate in a steroid plug.
The Model 6944 clinical study was a prospective, randomized,
multicenter trial evaluating the safety and efficacy of the Sprint
Quattro
Model 6944 lead for the treatment of life threatening
arrhythmias. The Model 6944 was compared to the market released
Sprint Model 6942 lead.
The Model 6944 lead was implanted in 112 patients and the
Model 6942 lead was implanted in 122 patients in 27 centers located
in the United States and Canada between February 25, 1999 and
July 30, 1999. All but 17 of the patients received the Model 7227 ICD,
the Model 7271 ICD or the Model 7273 ICD.
Patients had to meet the following eligibility criteria: 1) able to receive
a pectoral implant, and 2) survival of at least one episode of cardiac
arrest due to a ventricular tachyarrhythmia or episodes of recurrent,
poorly tolerated, sustained VT (spontaneous or induced). In addition,
patients in Canada could be included in the study if they were able to
receive a pectoral implant and met all of the following three
conditions: 1) prior myocardial infarction, 2) a left ventricular ejection
fraction of <
35%, and 3) had a documented history of nonsustained
VT with inducible ventricular tachyarrhythmia.
Patients studied
Patient demographics for both the Model 6944 lead and the Model
6942 lead are provided in Table 2.
6948 Technical manual English 11
Table 2. Model 6944 vs. Model 6942 patient demographics
Patient demographic 6944 (n = 112) 6942 (n =122)
Gender (N,%)
Male 93 (83.0%) 101 (82.8%)
Female 19 (17.0%) 21 (17.2%)
Age (years)
Mean 64.7 65.6
Range (32.0 - 84.6) (41.0 - 88.8)
Standard deviation 12.2 10.5
Primary indication (mutually exclusive, N,%)
SCD 13 (11.6%) 14 (11.5%)
VT 64 (57.1%) 78 (63.9%)
SCD/VT 34 (30.4%) 30 (24.6%)
MADIT 1 (0.9%) 0
Primary cardiovascular history (non-exclusive, N,%)
CAD and MI 77 (68.8%) 90 (73.8%)
CAD without MI 14 (12.5%) 18 (14.8%)
MI without CAD 9 (8.0%) 5 (4.1%)
Cardiomyopathy (dilated/
ischemic) 65 (58.0%) 85 (69.7%)
Primary electrical disease 1 (0.9%) 2 (1.6%)
Valvular heart disease 41 (36.6%) 29 (23.8%)
Pacemaker dependence 5 (4.5%) 5 (4.1%)
Congestive heart failure 58 (51.8%) 64 (52.5%)
Ejection fraction (%)
Mean 32.1 32.0
Range 10 - 68 4 - 70
Standard deviation 14.2 14.1
Not available 7 (6.3%) 2 (1.6%)
NYHA classification (N,%)
Class I 29 (25.9%) 26 (21.3%)
Class II 54 (48.2%) 63 (51.6%)
Class III 23 (20.5%) 28 (23.0%)
Class IV 4 (3.6%) 3 (2.5%)
Unknown 2 (1.8%) 2 (1.6%)
Objectives
The primary objectives of the study were to show equivalence in:
■
Ventricular lead-related event-free survival at three months
■
Pacing thresholds at one and three months
■
R-wave amplitudes at three months.
12 English 6948 Technical manual
Methods
Pulse width thresholds, R-wave amplitudes (EGM), pacing lead
impedances, and subthreshold high voltage lead impedances were
measured at implant and at one and three months post-implant.
Adverse events were collected throughout the study.
Result addressing the primary objective (ventricular
lead-related event-free survival at three months)
The Kaplan-Meier estimate of the ventricular lead-related event-free
survival at three months was 92.7% (95% confidence interval of
86.0% to 96.3%) for the Model 6944 lead and 97.4% (95%
confidence interval of 92.2% to 99.2%) for the Model 6942 lead. The
upper 95% confidence limit on the difference of 4.7% between the
Model 6944 and the Model 6942 leads was 9.4%, which is below the
equivalence of 10%. Thus the ventricular lead-related event-free
survival at three months for the Model 6944 lead was equivalent to
that of the Model 6942 lead.
Result addressing the primary objective (pacing thresholds at
one month and three months)
The upper 95% confidence limits on the differences in average pulse
width thresholds at one volt pulse amplitude between the Model 6944
lead and the Model 6942 lead were 0.059 ms at one month and 0.043
ms at three months. Since the upper 95% confidence limits were
below the equivalence bound of 0.10 ms, the pulse width thresholds
at one and three months for the Model 6944 lead are equivalent to
those of the Model 6942 lead.
Result addressing the primary objective (R-wave amplitudes at
three months)
The difference in mean R-wave amplitudes between the Model 6944
and the Model 6942 leads at three months was 1.4 mV with an upper
confidence limit of 2.16 mV. The objective was written with an
equivalence bound of 2 mV. However, this equivalence bound did not
take into account the differences in the sensing mechanisms of the
Model 6944 (true bipolar) and the Model 6942 (integrated bipolar)
leads. Even though the R-wave amplitudes of the Model 6944 lead
are not equivalent to the Model 6942 lead (with equivalence defined
as to within 2 mV), the R-wave amplitudes of the Model 6944 lead are
on average consistent over time and of adequate magnitude for
clinically acceptable sensing performance.
Pace/sense measurement results
The pace/sense measurements for the Model 6944 lead are
summarized in Table 3 and the pace/sense measurements for the
Model 6942 are summarized in Table 4.
6948 Technical manual English 13
Tab l e 3. Model 6944 pace/sense measurements at implant,
Pulse width thresholds at one volt
N 105 86 90
Median (ms) 0.10 0.20 0.20
Range (ms) (0.03 - 0.40) (0.03 - 0.90) (0.03 - 1.40)
R-wave amplitude (EGM)
N 110 100 99
Mean (mV) 9.1 9.5 9.2
Standard deviation 2.7 3.9 3.2
Pacing lead impedance
N 112 103 101
Median (ohms) 985 776 776
Range (ohms) (564 - 1722) (410 - 1389) (410 - 1156)
High voltage lead impedance (subthreshold)
N 105 97 96
Median (ohms) 14 17 17
Range (ohms) (10 - 25) (12 - 30) (12 - 32)
1 month, 3 months
Implant 1 month 3 months
Tab le 4. Model 6942 pace/sense measurements at implant,
Pulse width thresholds at one volt
N 111 107 96
Median (ms) 0.10 0.12 0.20
Range (ms) (0.03 - 2.00) (0.03 - 1.00) (0.03 - 1.00)
R-wave amplitude (EGM)
N 119 111 100
Mean (mV) 10.3 11.0 10.6
Standard deviation 3.7 4.0 3.5
Pacing lead impedance
N 120 112 105
Median (ohms) 412.5 410 410
Range (ohms) (275 - 776) (275 - 716) (275 - 661)
High voltage lead impedance (subthreshold)
N 110 101 98
Median (ohms) 14 18 17.5
Range (ohms) (10 - 21) (14 -27) (13 - 23)
1 month, 3 months
Implant 1 month 3 months
14 English 6948 Technical manual
Model 6944 conclusion
The Model 6944 lead is equivalent to the Model 6942 lead with
respect to safety and pacing performance. The sensing performance
of the Model 6944 lead is clinically appropriate.
The Model 6944 lead’s higher impedance values and low pacing
threshold combine to reduce pacing system energy requirements potentially improving pacing system longevity. For specific pacing
system longevity values, refer to the applicable implantable
cardioverter defibrillator product literature.
The clinical experience with the Model 6944 lead demonstrates that
the lead is safe and effective for human use.
Model 4074 (CapSure Sense tip electrode) clinical study
A multi-center, prospective, nonrandomized, historically controlled
clinical study conducted at 19 investigational sites in the United
States and 4 investigational sites in Canada compared the
Model 4074 and Model 4574 pacing leads to the Medtronic
Model 4092, Model 4592, and Model 5072 pacing leads (historical
control leads).
Clinical experience from the market released Model 4092 and
Model 4592 leads was used as the historical control for the safety,
pacing threshold, ventricular sensing, and impedance objectives. The
market released Model 5072 lead was used as the historical control
for the atrial sensing objective because it has a tip to ring spacing of
10 mm which is similar to the 9 mm tip to ring spacing in the
Model 4574 lead.
During the study, 132 patients received Model 4074 leads in the
ventricle and 132 patients received Model 4574 leads in the atrium. A
total of 132 patients participated in the clinical study.
Primary objectives
The clinical study has four primary objectives for safety and
effectiveness.
■
Lead related events
– Verify the safety of the Model 4074 lead as measured by
ventricular lead-related adverse events compared to the
Model 4092.
– Verify the safety of the Model 4574 lead as measured by
atrial lead-related adverse events compared to the
Model 4592.
6948 Technical manual English 15
■
Pacing performance
– Verify pacing performance of the Model 4074 lead as
measured by ventricular pacing thresholds compared to the
Model 4092.
– Verify pacing performance of the Model 4574 lead as
measured by atrial pacing thresholds compared to the
Model 4592.
■
Sensing performance
– Verify sensing performance of the Model 4074 lead as
measured by ventricular R-wave amplitudes compared to
the Model 4092.
– Verify sensing performance of the Model 4574 lead as
measured by atrial P-wave amplitudes compared to the
Model 5072.
■
Lead impedance
– Verify pacing impedance of the Model 4074 lead as
measured by ventricular pacing impedance compared to the
Model 4092.
– Verify pacing impedance of the Model 4574 lead as
measured by atrial pacing impedance compared to the
Model 4592.
Results
For Model 4074 lead related adverse events, the 95% upper
confidence bound on the difference between lead-related adverse
event rates was 7.75%, which is below the 10% upper bound criteria
(Table 5). Therefore, the objective concerning the equivalence of
ventricular lead-related adverse event rates was met. For Model 4574
lead related adverse events, the 95% upper confidence bound on the
difference between lead-related adverse event rates was 4.98%,
which is below the 10% upper bound criteria (Table 6). Therefore, the
objective concerning the equivalence of atrial lead-related adverse
event rates was met.
Tab l e 5. Ventricular lead related events: number (rate per patient month)
Event Complication Observation
Failure to capture/Loss of capture 1 (0.002) 0
Lead dislodgement 6 (0.013) 0
a
Other
To ta l: 8 (0.017) 0 (0)
a
During atrial lead placement, the physician elected to reposition the
ventricular lead, which required a longer lead length.
1 (0.002) 0
16 English 6948 Technical manual
Tab le 6. Atrial lead related events: number (rate per patient month)
Event Complication Observation
Elevated pacing thresholds 2 (0.004) 1 (0.002)
Failure to capture/Loss of capture 2 (0.004) 1 (0.002)
Lead dislodgement 4 (0.008) 0
To ta l: 8 (0.017) 2 (0.004)
For Model 4074 pacing performance, the 95% upper confidence
bound on the difference between the two means was 0.011 ms, which
was below the 95% upper bound criteria of 0.06 ms. Therefore, the
objective concerning the equivalence of ventricular pulse width
thresholds was met (Figure 1).
Figure 1. Ventricular pulse width thresholds at 2.5 V
6948 Technical manual English 17
For Model 4574 pacing performance, the 95% upper confidence
bound on the difference between the two means was 0.008 ms, which
was below the 95% upper bound criteria of 0.06 ms. Therefore, the
objective concerning the equivalence of atrial pulse width thresholds
was met (Figure 2).
Figure 2. Atrial pulse width thresholds at 2.5 V
For Model 4074 sensing performance, the 95% upper confidence
bound on the difference between the two means was 0.997 mV, which
was below the 95% upper bound criteria of 3.0 mV. Therefore, the
objective concerning the equivalence of ventricular R-wave
amplitudes was met (Figure 3).
Figure 3. Ventricular R-wave amplitude
18 English 6948 Technical manual
For Model 4574 sensing performance, the 95% upper confidence
bound on the difference between the two means was 0.003 mV, which
was below the 95% upper bound criteria of 1.5 mV. Therefore, the
objective concerning the equivalence of atrial P-wave amplitudes was
met (Figure 4).
4574
Figure 4. Atrial P-wave amplitude
For Model 4074 lead impedance, the 95% upper confidence bound
on the difference between the two means was -59 Ω, which was
below the 95% upper bound criteria of 200 Ω. Therefore, the objective
concerning the equivalence of ventricular pacing impedances was
met (Figure 5).
Figure 5. Ventricular pacing impedances
6948 Technical manual English 19
For Model 4574 lead impedance, the 95% upper confidence bound
on the difference between the two means was -21 Ω, which was
below the 95% upper bound criteria of 200 Ω. Therefore, the objective
concerning the equivalence of atrial pacing impedances was met
(Figure 6).
Figure 6. Atrial pacing impedances
Secondary objective
Lead performance with Ventricular Capture Management
■
Characterize the distribution of false negative increases in
ventricular output due to the Ventricular Capture Management
feature.
Results
In order to fully evaluate Ventricular Capture Management (VCM), a
patient needs to have a continuum of data from each device
interrogation. There were 122 patients with Ventricular Capture
Management data available to analyze. Of those patients, six
experienced at least one false negative in ventricular output due to
the Ventricular Capture Management feature. The 1-sided lower
confidence bound on the proportion of patients who did not
experience a false negative (116/122 = 95.1%) was 90.5%.
Directions for use
Proper surgical procedures and sterile techniques are the
responsibility of the medical professional. The following procedures
are provided for information only. Each physician must apply the
information in these instructions according to professional medical
training and experience.
The implant procedure generally includes the following steps:
■
Opening the package
■
Inserting the lead
■
Positioning the lead
20 English 6948 Technical manual
■
Taking electrical measurements and defibrillation efficacy
measurements
■
Anchoring the lead
■
Connecting the lead
■
Placing the device and leads into the pocket
■
Post-implant evaluation
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. Spread the slot in the disc-shaped tine protector at the distal
end of the lead and carefully remove it from the lead.
3. Inspect the lead. Leads shorter than 85 cm should have
1 anchoring sleeve on the lead body. Leads 85 cm or longer
should have 2 anchoring sleeves on the lead body.
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 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.
Caution: Certain anatomical abnormalities, such as thoracic
outlet syndrome, may also precipitate pinching and subsequent
fracture of the lead.
Caution: 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 7).
6948 Technical manual English 21
Figure 7.
■
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 8).
Note: A percutaneous lead introducer (PLI) kit may be used to
facilitate insertion. Refer to the technical manual packaged with
an appropriate percutaneous introducer for further instructions.
Figure 8.
3. Advance the lead into the right atrium using a straight stylet to
facilitate movement through the veins.
Positioning the 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. Replacing the straight stylet with a
gently curved stylet may add control in maneuvering the lead
through the tricuspid valve.
22 English 6948 Technical manual
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 9).
Figure 9.
Note: Passing the lead tip through the tricuspid valve or
chordae tendineae may be difficult due to the tines and the
flexible nature of the lead body. Rotating the lead body as the
tip passes through the valve may 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 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.
4. After final positioning, remove the stylet guide and stylet
completely. When removing the stylet guide, grip the lead firmly
just below the connector pin, to help prevent possible lead
dislodgment.
5. Obtain final electrical measurements as defined in “Taking
electrical measurements and defibrillation efficacy
measurements” on page 23.
Taking electrical measurements and defibrillation
efficacy measurements
Caution: Prior to taking electrical or defibrillation efficacy
measurements, move objects made of 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 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.
6948 Technical manual English 23
2. Use a testing device, such as a pacing system analyzer, for
obtaining electrical measurements. For information on the use
of the testing device, consult the product literature for
that device.
In order to demonstrate reliable defibrillation efficacy, obtain final
defibrillation measurements for the lead system.
Tab l e 7. Recommended measurements at implant
(when using a pacing system analyzer)
Measurements required Acute
a
lead system
Chronic
b
lead system
Capture threshold
(at 0.5 ms pulse width) ≤ 1.0 V ≤ 3.0 V
Pacing impedance 200 - 1000 ohms 200 - 1000 ohms
Filtered R-wave amplitude
(during sinus rhythm)
≥ 5 mV (during
sinus rhythm)
≥ 3 mV (during
sinus rhythm)
Slew rate ≥ 0.75 V/s ≥ 0.45 V/s
a
< 30 days after implant.
b
> 30 days after implant.
If initial electrical measurements deviate from the recommended
values, it may be necessary to repeat the testing procedure
15 minutes after final positioning. Initial electrical measurements may
deviate from the recommended values:
■
Initial impedance values may exceed the measuring
capabilities of the testing device, resulting in an error message.
■
Values may vary depending upon lead type, implantable device
settings, cardiac tissue condition, and drug interactions.
If electrical measurements do not stabilize to acceptable levels, it may
be necessary to reposition the lead and repeat the testing procedure.
In order to keep patient morbidity and mortality to a minimum,
patients should be rescued promptly with an external defibrillator if
the implanted lead system fails to terminate a VF episode. At least
5 minutes should elapse between VF inductions.
For more information on obtaining electrical measurements, consult
the technical manual supplied with the testing device.
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 10).
■
Do not tie a suture directly to the lead body (Figure 10).
24 English 6948 Technical manual
Figure 10.
Use the following steps to anchor the lead using all 3 grooves:
Note: The anchoring sleeves contain 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 11).
Figure 11.
3. Use at least 1 additional suture in 1 of the grooves to secure the
anchoring sleeve and lead body to the fascia.
4. A second anchoring sleeve is provided with leads 85 cm or
longer. For abdominal implants, redundant lead body (for
example, a curve for strain relief) should be placed just proximal
to the first anchoring sleeve. Then, the second anchoring
sleeve may be lightly sutured to the lead body and fascia to hold
the curve in place. This procedure helps isolate the vein entry
site from tension on the proximal end of the lead body.
5. 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.
Connecting the lead
Use the following steps to connect the lead to an implantable device:
1. Carefully remove the stylet and stylet guide. When removing
the stylet and stylet guide, grip the lead firmly just below the
connector pin, to prevent dislodgment.
2. Insert the lead connectors into the connector block. Consult the
product literature packaged with the implantable device for
instructions on proper lead connections.
6948 Technical manual English 25
Placing the device and leads 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 dislodgment (Figure 12).
Figure 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 13).
Figure 13.
2. Insert the device and leads into the pocket.
3. Before closing the pocket, verify sensing, pacing,
cardioversion, and defibrillation efficacy.
Post-implant evaluation
After implant, monitor the patient’s electrocardiogram until the patient
is discharged. If a lead dislodges, it usually occurs during the
immediate postoperative period.
Recommendations for verifying proper lead positioning include x-rays
and pacing/sensing thresholds taken at pre-hospital discharge,
3 months after implant, and every 6 months thereafter.
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.
26 English 6948 Technical manual
Detailed device description
Specifications (nominal)
Parameter Model 6948
Type Quadripolar
Position Right ventricle
Fixation Tined
Length 40-110 cm
Connectors Unipolar (2): DF-1
Bipolar: IS-1
Materials Conductors: MP35N coil
Insulator: Silicone/ETFE
Electrodes: Titanium nitride coated platinum
RV/SVC coils: Platinum-clad tantalum
DF-1 connector pins: Stainless steel
IS-1 connector pin and ring: Stainless steel
Steroid Type: Dexamethasone acetate
Amount: 1.0 mg maximum (combined)
Steroid binder: Silicone
Conductor resistances
Pacing (unipolar): 44.7 Ω at 65 cm
Pacing (bipolar): 91.7 Ω at 65 cm
Defibrillation: < 2.4 Ω at 65 cm
Diameters Lead body: 2.2 mm
Lead introducer (recommended size)
Without guide wire: 7.0 French
With guide wire: 9.0 French
MP35N composite cables
Overlay: Polyurethane
iridium
Dexamethasone sodium phosphate
Tip: 2.2 mm
6948 Technical manual English 27
Specifications drawing (nominal)
180 mm
12 mm
8 mm
Tip electrode
Surface area: 2.5 mm
Ring electrode
Surface area: 20.2 mm
RV coil electrode
Length: 62 mm
Surface area: 513 mm
2
2
2
Electrical shadow area: 430 mm
SVC coil electrode
Length: 80 mm
Surface area: 663 mm
2
Electrical shadow area: 556 mm
Anchoring sleeve
Note: Leads 85 cm or
longer have 2 anchoring
sleeves
2
2
DF-1 connector
(red band)
Note: Connector
pin is common to
RV coil electrode
IS-1 BI connector
Note: Connector pin is common
DF-1 connector
(blue band)
Note: Connector
pin is common to SVC
coil electrode
to tip electrode; connector ring is
common to ring electrode
28 English 6948 Technical manual
Medtronic warranty
For complete warranty information, see the accompanying warranty
document.
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 medical consultation,
Medtronic can often refer product users to outside medical
consultants with appropriate expertise. 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.
6948 Technical manual English 29
World Headquarters
Medtronic, Inc.
710 Medtronic Parkway
Minneapolis, MN 55432-5604
USA
Internet: www.medtronic.com
Tel. 763-514-4000
Fax 763-514-4879
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
Heart Failure: 1-800-505-4636
Europe/Africa/Middle East
Headquarters
Medtronic Europe Sàrl
Route du Molliau 31
Case Postale
CH-1131 Tolochenaz
Switzerland
Internet: www.medtronic.co.uk
Tel. 41-21-802-7000
Fax 41-21-802-7900
Medtronic E.C. Authorized
Representative/Distributed by
Medtronic B.V.
Earl Bakkenstraat 10
6422 PJ Heerlen
The Netherlands
Tel. 31-45-566-8000
Fax 31-45-566-8668
Asia
Medtronic International Ltd.
Suite 1602 16/F, Manulife Plaza
The Lee Gardens,
33 Hysan Avenue
Causeway Bay
Hong Kong
Tel. 852-2891-4068
Fax 852-2591-0313
Aust ralia
Medtronic Australasia Pty. Ltd.
Unit 4/446 Victoria Road
Gladesville NSW 2111
Australia
Tel. 61-2-9879-5999
Fax 61-2-9879-5100
Canada
Medtronic of Canada Ltd.
6733 Kitimat Road
Mississauga, Ontario L5N 1W3
Tel. 905-826-6020
Fax 905-826-6620
Toll-free in Canada:
1-800-268-5346
Japan
Medtronic Japan
Solid Square West Tower 6F,
580 Horikawa-cho, Saiwai-ku,
Kawasaki, Kanagawa 210-0913
Japan
Tel. 81-44-540-6112
Fax 81-44-540-6200
*A02224001*
© Medtronic, Inc. 2004
All Rights Reserved
A02224001
2004-09-14
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