Medtronic 457430 Technical Manual

CAPSURE SENSE® 4574

Steroid-eluting, bipolar, implantable, tined, atrial, transvenous lead

Technical Manual

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

The following list includes trademarks or registered trademarks of Medtronic in the United States and possibly in other countries.
All other trademarks are the property of their respective owners.

CapSure, CapSure Sense, Capture Management, Medtronic

Contents

1 Description 3
2 Drug component description 3
3 Indications 3
4 Contraindications 3
5 Warnings and precautions 4
6 Drug information 5
7 Potential adverse events 6
8 Clinical data 6

9 Directions for use 9
10 Specifications (nominal) 12
11 Medtronic warranty 14
12 Service 14

1 Description

The Medtronic CapSure Sense Model 4574 steroid-eluting,
bipolar, implantable, tined, atrial, transvenous lead is designed
for atrial pacing and sensing. The platinum alloy tip and ring
electrodes feature a high-active surface area of titanium nitride
microstructure. This electrode configuration contributes to low
polarization.

The tip electrode of the lead incorporates a steroid-eluting plug
containing dexamethasone acetate. The tip electrode contains a
target nominal dosage of 272 µg of dexamethasone. Upon
exposure to body fluids, the steroid elutes from the electrode.

The lead is designed to provide low chronic pacing thresholds via
steroid treatment of cardiac tissue near the lead tip. Steroid
suppresses the inflammatory response that is believed to cause
threshold rises typically associated with implanted pacing
electrodes.

The distal portion of the lead is J-shaped. This facilitates
placement of the electrode in or near the apex of the right atrial
appendage.

The lead features four polyurethane tines near the electrode tip,
MP35N nickel alloy conductors, polyurethane outer insulation,
silicone inner insulation, and an IS-1 Bipolar (BI)1 lead connector.

1.1 Package contents

Leads and accessories are supplied sterile. Each package
contains the following items:

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1 lead with anchoring sleeve, stylet, and stylet guide

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1 vein lifter

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extra stylets

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product documentation

1.2 Accessory descriptions

Dispose of all single-use accessories according to local
environmental requirements.

Anchoring sleeve – An anchoring sleeve secures the lead to
prevent it from moving and protects the lead insulation and
conductors from damage caused by tight sutures.

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.

Vein lifter – A vein lifter facilitates lead insertion into a vein.

2 Drug component description

The active ingredient in the Model 4574 lead is dexamethasone
acetate. Dexamethasone acetate is 9-Fluoro-11β,
17,21-trihydroxy-16α-methylpregna-1,4-diene-3,20-dione
21-acetate. Dexamethasone acetate has a molecular formula of
C24H31FO6 and a molecular weight of 434.50. The MCRD
excipient is silicone. See Figure 1 for the structural formula.

Figure 1.

The target dosage of dexamethasone acetate is 272 µg per lead.

3 Indications

The Model 4574 implantable, atrial, transvenous lead has
application where implantable atrial single-chamber or
dual-chamber pacing systems are indicated. The lead is intended
for pacing and sensing in the atrium.

4 Contraindications

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Use of atrial tined transvenous leads may be contraindicated
in the absence of a right atrial appendage.

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Use of steroid-eluting transvenous leads is contraindicated in
patients for whom a single dose of 272 µg dexamethasone
acetate may be contraindicated.

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IS-1 BI refers to an International Connector Standard (ISO 5841-3) whereby pulse generators and leads so designated are assured of a basic mechanical fit.

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5 Warnings and precautions

Note: Medical procedure warnings and precautions that pertain

to the Medtronic implanted system are provided in the manual that
is packaged with the device or on the Medtronic Manual Library
website (www.Medtronic.com/manuals).

Line-powered and battery-powered equipment – An
implanted lead forms a direct current path to the myocardium.
During lead implant and testing, use only battery-powered
equipment or line-powered equipment specifically designed for
this purpose to protect against fibrillation that may be caused by
alternating currents. Line-powered equipment used in the vicinity
of the patient must be properly grounded. Lead connector pins
must be insulated from any leakage currents that may arise from
line-powered equipment.

Diathermy treatment (including therapeutic ultrasound) –

Diathermy is a treatment that involves the therapeutic heating of
body tissues. Diathermy treatments include high frequency, short
wave, microwave, and therapeutic ultrasound. Except for
therapeutic ultrasound, do not use diathermy treatments on
cardiac device patients. Diathermy treatments may result in
serious injury or damage to an implanted device and leads.
Therapeutic ultrasound is the use of ultrasound at higher energies
than diagnostic ultrasound to bring heat or agitation into the body.
Therapeutic ultrasound is acceptable if treatment is performed
with a minimum separation distance of 15 cm (6 in) between the
applicator and the implanted device and leads.

Vessel and tissue damage – Use care when positioning the
lead. Avoid known infarcted or thin ventricular wall areas to
minimize the occurrence of perforation and dissection.

Single use – The lead and accessories are for single use only.

Inspecting the sterile package – Inspect the sterile package

with care before opening it.

●

If the seal or package is damaged, contact a Medtronic
representative.

●

Store at 25 °C (77 °F). Excursions from this storage
temperature are permitted in the range of 15 to 30 °C (59 to
86 °F). (See USP Controlled Room Temperature.) According
to USP excursion conditions, transient spikes up to 40 °C
(104 °F) are permitted as long as they do not exceed 24 hours.

●

Do not use the product after its expiration date.

Sterilization – Medtronic has sterilized the package contents
with ethylene oxide before shipment. This lead is for single use
only and is not intended to be resterilized.

Steroid use – It has not been determined whether the warnings,
precautions, or complications usually associated with injectable
dexamethasone acetate apply to the use of this highly localized,
controlled-release lead. For a list of potential adverse effects,
refer to the Physicians’ Desk Reference.

Handling the steroid tip – Avoid reducing the amount of steroid
available before implanting the lead. Reducing the available

amount of steroid may adversely affect low-threshold
performance.

●

Do not allow the electrode surface to come in contact with
surface contaminants.

●

Do not wipe or immerse the electrode in fluid, except blood,
at the time of implant.

Handling a tined lead – Handle the lead with care at all times.

●

Do not implant the lead if it is damaged. Return the lead to a
Medtronic representative.

●

Protect the lead from materials that shed small 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 immerse the lead in mineral oil, silicone oil, or any other
liquid, except blood, at the time of implant.

●

Do not use surgical instruments to grasp the lead.

●

Do not force the lead if resistance is encountered during lead
passage.

Handling the stylet – Handle the stylet with care at all times.

●

Curve the stylet before inserting it into the lead to achieve a
curvature at the lead’s distal end. Do not use a sharp object
to impart a curve to the distal end of the stylet.

●

Do not use excessive force or surgical instruments when
inserting the stylet into the lead.

●

Avoid overbending or kinking the stylet.

●

Use a new stylet when blood or other fluids accumulate on
the stylet. Accumulated blood or other fluids may damage the
lead or cause difficulty in passing the stylet into the lead.

Necessary hospital equipment – Keep external defibrillation
equipment nearby for immediate use during acute lead system
testing, the implant procedure, or whenever arrhythmias are
possible or intentionally induced during post-implant testing.

Magnetic resonance imaging (MRI) – An MRI is a type of
medical imaging that uses magnetic fields to create an internal
view of the body. Do not conduct MRI scans on patients who have
this device or lead implanted. MRI scans may result in serious
injury, induction of tachyarrhythmias, or implanted system
malfunction or damage.

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.

Chronic repositioning or removal of a tined lead – Proceed
with extreme caution if a lead must be removed or repositioned.
Chronic repositioning or removal of tined transvenous leads may
be difficult because of fibrotic tissue development on the lead. In
most clinical situations, it is preferable to abandon unused leads

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in place. Return all removed leads, unused leads, or lead sections
to Medtronic for analysis.

●

Lead removal may result in avulsion of the endocardium,
valve, or vein.

●

Lead junctions may separate, leaving the lead tip and bare
wire in the heart or vein.

●

Chronic repositioning of a lead may adversely affect a steroid
lead’s low-threshold performance.

●

An abandoned lead should be capped so that the lead does
not transmit electrical signals.

●

Severed leads should have the remaining lead end sealed
and the lead body sutured to adjacent tissue.

Connector compatibility – Although the lead conforms to the
IS-1 International Connector Standard, do not attempt to use the
lead with any device other than a commercially available
implantable pacing 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.

6 Drug information

6.1 Mechanism of action

Steroid suppresses the inflammatory response that is believed to
cause threshold rises typically associated with implanted pacing
electrodes. Dexamethasone acetate is a synthetic steroid of the
glucocorticoid family. Glucocorticoids have potent
anti-inflammatory actions via direct and indirect effects on major
inflammatory cells. Glucocorticosteroids bind to a cytoplasmic
glucocorticoid receptor as well as a membrane-bound receptor.
Binding to the cytoplasmic receptor leads to receptor activation
and translocation to the nucleus. The receptor interacts with
specific DNA sequences within the regulatory regions of affected
genes. Thus, glucocorticoids inhibit the production of multiple cell
factors that are critical in generating the inflammatory response.

6.2 Pharmacokinetics and metabolism

Pharmacokinetics – The pharmacokinetics (local drug levels

and systemic levels) of dexamethasone acetate and its
metabolites following implant were not evaluated in human
clinical trials. When delivered intra-muscularly, the lipid-soluble
dexamethasone acetate is slowly absorbed throughout the
tissue.

Metabolism – The conversion of dexamethasone acetate to
dexamethasone occurs within hours. The dexamethasone
alcohol (dexamethasone) is the active glucocorticoid used in this
Medtronic lead. Steroid is applied via MCRD (Monolithic
controlled release device) and eluted to the tissue interface where
it will be used. The form of the steroid, whether it is a prodrug or
the pharmacologically active dexamethasone, is irrelevant, as the
steroid is directly present at the injury site to treat the
inflammation. Dexamethasone acetate is hydrolyzed into
dexamethasone, which is readily absorbed by the surrounding

tissue and body fluids. Glucocorticoids, when given systemically,
are eliminated primarily by renal excretion of inactive metabolites.

6.3 Mutagenesis, carcinogenicity, and reproductive toxicity

The mutagenesis, carcinogenicity, and reproductive toxicity of
the Model 4574 lead have not been evaluated. However, the
mutagenesis, carcinogenicity, and reproductive toxicity of
dexamethasone acetate have previously been evaluated.

Mutagenesis – Genotoxicity evaluation of dexamethasone was
undertaken using in vitro and in vivo assays. Analyses of
chromosomal aberrations, sister-chromatid exchanges in human
lymphocytes, and micronuclei and sister-chromatid exchanges in
mouse bone marrow showed dexamethasone to be capable of
attacking the genetic material. However, the Ames/Salmonella
assay, both with and without S9 mix, did not show any increase
His+ revertants.

Carcinogenicity – Although adequate and well-controlled
animal studies have not been performed on Dexamethasone
acetate, use in humans has not shown an increase in malignant
disease.

Reproductive Toxicity – Adrenocorticoids have been reported
to increase or decrease the number and motility of spermatozoa.
However, it is not known whether reproductive capacity in
humans is adversely affected.

Pregnancy – Adrenocorticoids cross the placenta. Although
adequate studies have not been performed in humans, there is
some evidence that pharmacologic doses of adrenocorticoids
may increase the risk of placental insufficiency, decreased birth
weights or stillbirth. However, tetrogenic effects in humans have
not been confirmed.

Infants born to mothers who have received substantial doses of
adrenocorticoids during pregnancy should be carefully observed
for signs of hypoadrenalism and replacement therapy
administered as required.

Prenatal administration of dexamethasone to the mother to
prevent respiratory distress syndrome in the premature neonate
has not been shown to affect the child’s growth or development
adversely. Physiologic replacement doses of adrenocorticoids
administered for treatment of adrenal insufficiency are also
unlikely to adversely affect the fetus or neonate. Animal studies
have shown that adrenocorticoids increase the instance of cleft
palate, placental insufficiency, spontaneous abortions, and
intrauterine growth retardation.

Lactation – Problems in humans have not been documented.
Adrenocorticoids are excreted in breast milk and may cause
unwanted defects such as growth suspension and inhibition of
endogenous steroid production in the infant.

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