Medtronic 694458 Technical Manual

SPRINT QUATTRO® 6944

Steroid eluting, quadripolar, ventricular lead with tined
tip and RV/SVC coil electrodes

Technical manual

Caution: Federal Law (USA) restricts this
device to sale by or on the order of a
physician.

The following are trademarks of Medtronic:
Medtronic and Sprint Quattro

Contents

Device description 5

Contents of package 5
Accessory descriptions 6

Indications for use 6

Contraindications 6

Warnings and precautions 7

Adverse events 9

Observed adverse events 9
Potential adverse events 11

Clinical studies 11

Directions for use 15

Opening the package 15
Inserting the lead 16
Positioning the lead 17
Taking electrical measurements and defibrillation efficacy

measurements 18
Anchoring the lead 20
Connecting the lead 21
Placing the device and leads into the pocket 21
Post-implant evaluation 22

Detailed device description 22

Specifications (nominal) 22
Specifications drawing (nominal) 23

Special notice 24

Service 24

6944 Technical Manual 3

Device description

The Medtronic Sprint Quattro Model 6944 steroid eluting,
quadripolar, ventricular lead with tined tip and right ventricular (RV)
and superior vena cava (SVC) coil electrodes is designed for pacing,
sensing, cardioversion, and defibrillation therapies.

The lead features tines, silicone insulation with overlay, and parallel
conductors. The four electrodes of the lead are tip, 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-1 connector (red band).

■

The SVC coil electrode is common to the connector pin of the
SVC DF-1 connector (blue band).

1

The IS-1
passage. The DF-1

The RV and SVC coils deliver cardioversion and defibrillation
therapies. Pacing and sensing occur between the tip and
ring electrodes.

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.

bipolar leg of the trifurcation features a lumen for stylet

2

connectors will not accept stylets.

Contents of package

The lead and accessories are provided sterile. Each package
contains the following:

■

One lead with one3 radiopaque anchoring sleeve, stylet,
stylet guide

■

One vein lifter

■

One slit anchoring sleeve

■

Extra stylets

■

Pin caps

■

Product literature

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.

3

Two anchoring sleeves are provided with leads 85 cm or longer.

6944 Technical Manual English 5

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 sleeves – An anchoring sleeve secures the lead from

moving and protects the lead insulation and conductors from damage
caused by tight ligatures.

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 for use

The lead is intended for single, long-term use in the right ventricle.

This lead has application for patients in which 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.

6 English 6944 Technical Manual

Warnings and precautions

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 (130°F).

■

Do not resterilize more than one 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 implantation of the system.

Steroid elution – 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 a listing of potentially adverse effects,
refer to the Physicians’ 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 implantation:

■

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 implantation.

6944 Technical Manual English 7

Handling the lead – Leads should be handled 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.

■

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 implantation.

■

Inserting the lead using a lead introducer that features a
hemostasis valve may require a larger introducer than the size
recommended. Do not withdraw the lead through a hemostasis
valve, to avoid distortion of the coil electrode.

Handling the stylets – Use care when handling stylets:

■

Do not use excessive force or surgical instruments when
inserting a stylet.

■

Avoid overbending, kinking, or blood contact.

■

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, implantation 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 implantation 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 two
anchoring sleeves. Use both anchoring sleeves to assure adequate
fixation, see the section “Anchoring the lead.”

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.

8 English 6944 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, and/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 or unused leads 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 a steroid eluting
lead’s low-threshold performance.

■

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.

Adverse events

Observed adverse events

The Sprint Quattro Model 6944 steroid eluting, quadripolar, tined,
ventricular, RV/SVC lead was utilized in the Model 6944 clinical study.
The Model 6944 clinical study was randomized between two patient
groups, with one group receiving the Model 6944 lead and the other
group receiving the Model 6942 lead. One hundred twelve (112)
patients were implanted with the Model 6944 lead and 122 patients
were implanted with the Model 6942 lead from February 25, 1999
through July 31, 1999. The required three month follow-up visits were
completed for this patient population as of November 30, 1999. As of
November 30, 1999, the Model 6944 lead exposure was 545 patient
months. Individual patient exposure averaged 4.9 months, with a
range of 0.5 to 7.6 months. As of November 30, 1999, the Model 6942
lead exposure was 551.6 patient months. Individual patient exposure
averaged 4.5 months, with a range of 0.1 to 7.4 months.

6944 Technical Manual English 9

Fourteen patient deaths occurred in this patient group during the
follow-up period. Thirteen of the deaths were reviewed and judged to
be non-system related by an independent advisory committee. One
patient died from complications of a motor vehicle accident and the
ICD system was not interrogated or explanted. Nine patients who
received the Model 6942 lead died of the following causes:
cardiogenic shock/myocardial infarction (1), ventricular fibrillation/
acute myocardial infarction (1), end stage congestive heart failure (1),
end stage congestive heart failure with ischemic cardiomyopathy (1),
heart failure (1), respiratory arrest (1), acute renal failure (1),
ischemic bowel (1), motor vehicle accident (1). Five patients who
received the Model 6944 lead died of the following causes:
congestive heart failure (1), cardiogenic shock following surgery (1),
pneumonia and respiratory failure (1), respiratory arrest (1),
myeloma (1).

Ventricular lead-related adverse events categorized as occurring at
implant, complications, and observations are summarized in Table 1.

Table 1. Model 6944 vs. Model 6942 Lead-related

complications and observations

6944

# of events

(n=112)

At implant

Cardiac
tamponade 1 1 0 0

Failure to implant
lead 0 0 1 1

To t al 1 1 1 1

Complications

Suspected micro­dislodgment 1 1 0 0

Loss of capture 1 1 1 1

Increased DFT 0 0 1 1

To t al 2 2 2 2

Observations

Decreased R­wave amplitude 4 4 1 1

HVB impedance
< 10 ohms
(Patient alert
triggered) 1 1 0 0

Increased pacing
threshold 1 1 1 1

Lead poking
under skin 1 1 0 0

Sensing of
charge noise 1 1 0 0

Vein occlusion 1 1 1 1

To t al 9 9 3 3

6944

#ofpatients

(n=112)

6942

#ofevents

(n=122)

6942

#ofpatients

(n=122)

10 English 6944 Technical Manual

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 studies

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 <
VT with inducible ventricular tachyarrhythmia.

35%, and 3) had a documented history of nonsustained

6944 Technical Manual English 11

Patients studied – Patient demographics for both the Model 6944
lead and the Model 6942 lead are provided in Table 2.

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 6944 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.

6944 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 6944 Technical Manual

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.

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 implantation procedure generally includes the following steps:

■

Opening the package

■

Selecting an insertion site

■

Positioning the lead

■

Taking electrical measurements and defibrillation
efficacy measurements

■

Anchoring the lead

■

Connecting the lead

■

Placing the device and leads into the pocket

Opening the package

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 disk tip 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 one
anchoring sleeve. Leads 85 cm or longer should have two
anchoring sleeves.

6944 Technical Manual English 15

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 techniques described as follows:

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/clavicular (thoracic inlet) space.

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 1).

Figure 1.

■

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 2).

Note: A percutaneous lead introducer kit may be used to
facilitate insertion.

16 English 6944 Technical Manual

Figure 2.

3. Advance the lead into the right atrium or the inferior vena cava
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.

Position the lead in the right ventricle using the technique described
as follows:

1. After the lead tip is passed into the atrium or the inferior vena
cava, 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.

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 3).

Figure 3.

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.

6944 Technical Manual English 17

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 (Figure 4). Use fluoroscopy
(lateral position) to ensure that the tip is not in a retrograde
position or lodged in the coronary sinus.

Figure 4.

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 the
following section.

Taking electrical measurements and defibrillation efficacy measurements

Caution: Prior to taking electrical or defibrillation efficacy

measurements, move objects made from conductive materials, such
as guidewires, away from all electrodes. Metal objects, such as
guidewires, can short a lead and an active implantable device,
causing electrical current to bypass the heart and possibly damage
the implantable device and lead.

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 on the use
of the testing device, consult the product literature for
that device.

In order to demonstrate reliable defibrillation efficacy, obtain
final electrical measurements for the lead system.

18 English 6944 Technical Manual

Recommended measurements at implant

(when using a pacing system analyzer)

Measurements required Acute lead system Chronic lead system

Capture threshold
(at 0.5 ms pulse width) ≤ 1.0 V ≤ 3.0 V

Pacing impedance ≥ 700 ohms ≥ 700 ohms

Filtered R-wave amplitude
(during sinus rhythm) ≥ 5mV ≥ 3mV

Slew rate ≥ 0.75 V/s ≥ 0.45 V/s

The Model 6944 defibrillation lead will exhibit higher acute and
chronic pacing impedances than previous Medtronic
defibrillation leads. Implant pacing impedance may exceed the
measurement range of some testing devices (e.g., >2000 Ω).
Therefore, if initial painless lead impedance measurements
deviate from the recommended values, it may be necessary to
repeat the testing procedure 15 minutes after final positioning.
If painless lead impedance measurements continue to exceed
the measurement range, the impedance is acceptable under
the following conditions:

■

Pacing thresholds and R-wave amplitudes are within the
recommended values.

■

Fluoroscopic images indicate that the electrodes are in an
acceptable position.

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.

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.

6944 Technical Manual English 19

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.

■

During anchoring, take care to avoid dislodging the lead tip.

■

Do not secure ligatures so tightly that they damage the vein,
lead, or anchoring sleeve (Figure 5).

■

Do not tie a ligature directly to the lead body (Figure 5).

Figure 5.

Anchor the lead using all three grooves, as described in the
following procedure:

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 three grooves (Figure 6).

Figure 6.

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 second anchoring sleeve is provided with leads 85 cm or
longer. For abdominal implants, redundant lead body (e.g., 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.

20 English 6944 Technical Manual

Connecting the lead

Connect the lead to an implantable device:

1. Carefully remove the stylet and stylet guide completely. When
removing the 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.

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 7).

Figure 7.

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 8).

Figure 8.

2. Insert the device and leads into the pocket.

3. Before closing the pocket, verify sensing, pacing,
cardioversion, and defibrillation efficacy.

6944 Technical Manual English 21

Post-implant evaluation

After implantation, 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, three
months after implant and every six months thereafter.

In the event of a patient death, all implanted leads and devices should
be explanted and returned to Medtronic with a completed Product
Information Report. Call the appropriate phone number on the back
cover if there are any questions on product handling procedures.

Detailed device description

Specifications (nominal)

Parameter Model 6944

Type Quadripolar

Position Right ventricle

Fixation Tined

Length 20-110 cm

Connectors Unipolar(2): DF-1

Bipolar: IS-1

Materials Conductors: MP35N composite coil

MP35N composite cables

MP35N cables

Insulator: Silicone

Overlay: Polyurethane

Electrodes: Platinized platinum alloy

RV/SVC coils: Platinum alloy-clad tantalum

DF-1 pins: Stainless steel

IS-1 pin and ring: Stainless steel

Steroid binder: Silicone

Steroid Type: Dexamethasone acetate

Dexamethasone sodium
phosphate

Amount: 1.0 mg maximum (combined)

Conductor resistances Pacing (unipolar): 4.5 Ω (65 cm)

Pacing (bipolar): 44.5 Ω (65 cm)

Defibrillation: < 1.2 Ω (65 cm)

Diameters Lead body: 2.7 mm

Tip: 2.7 mm

Lead introducer (recommended size)

Without guidewire: 9.0 French

With guidewire: 10.5 French

22 English 6944 Technical Manual

Specifications drawing (nominal)

Tip electrode

Surface area: 1.6 mm

Ring electrode

Surface area: 17 mm

2

2

RV coil electrode

Length: 57 mm
Surface area: 585 mm
Electrical shadow area: 483 mm

SVC coil electrode

Length: 80 mm
Surface area: 819 mm
Electrical shadow area: 677 mm

Anchoring sleeve

Note: Leads 85 cm or
longer have two anchoring
sleeves

2

2

2

2

DF-1 connector
(red band)
Note: Connector

pin is common to
RV coil electrode

DF-1 connector
(blue band)
Note: Connector

pin is common to
SVC coil electrode

IS-1 BI connector
Note: Connector pin is com mon to tip electrode;

connector ring is common to ring electrode

6944 Technical Manual English 23

Special notice

Medtronic implantable leads are implanted in the extremely hostile
environment of the human body. Leads are necessarily very small in
diameter and must still be very flexible, which unavoidably reduces
their potential performance or longevity. Leads may fail to function for
a variety of causes, including, but not limited to: medical
complications, body rejection phenomena, allergic reaction, fibrotic
tissue, or failure of leads by breakage or by breach of their insulation
covering. In addition, despite the exercise of all due care in design,
component selection, manufacture, and testing prior to sale, leads
may be easily damaged before, during, or after insertion by improper
handling or other intervening acts. Consequently, no representation
or warranty is made that failure or cessation of function of leads will
not occur or that the body will not react adversely to the implantation
of leads or that medical complications (including perforation of the
heart) will not follow the implantation of leads or that the lead will, in
all cases, restore adequate cardiac function.

For complete warranty information, see the accompanying card
enclosed in the package.

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.

24 English 6944 Technical Manual

World Headquarters

Medtronic, Inc.
710 Medtronic Parkway
Minneapolis, MN 55432-5604
USA
www.medtronic.com
Tel. [phone]
Fax [phone]

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/Africa/Middle East
Headquarters

Medtronic International Trading
Sàrl
Route du Molliau 31
Case Postale 84
CH-1131 Tolochenaz
Switzerland
www.medtronic.co.uk
Tel. [phone]
Fax [phone]

Medtronic E.C. Authorized
Representative/Distributed by

Medtronic B.V.
Earl Bakkenstraat 10
6422 PJ Heerlen
The Netherlands
Tel. [phone]
Fax [phone]

Technical manuals:
www.medtronic.com/manuals

© Medtronic, Inc. 2007
M220682A002B
2007-12-17

*M220682A002*