Medtronic 694458 Technical Manual

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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.
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The following are trademarks of Medtronic: Medtronic and Sprint Quattro
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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
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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.
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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.
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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.
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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.
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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.
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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)
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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
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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
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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.
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World Headquarters
Medtronic, Inc. 710 Medtronic Parkway Minneapolis, MN 55432-5604 USA www.medtronic.com Tel. +1-763-514-4000 Fax +1-763-514-4879
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
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. +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
Technical manuals: www.medtronic.com/manuals
© Medtronic, Inc. 2007 M220682A002B 2007-12-17
*M220682A002*
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