The BIOTRONIK RETROX RX 53/60-BP and RETROX RX 45/53-JBP transvenous, active fixation endocardial leads are indicated for permanent pacing and sensing. Active fixation pacing leads with a bipolar (BP) IS-1 connector configuration are designed for use in conjunction with implantable pulse generators. The leads may be used with singleor dual-chamber pacing systems. RETROX RX-BP and RX-JBP leads differ in the shape of the distal portion of the lead. The RX-BP models are intended for placement in the ventricle or atrium and have straight distal ends. The RX-JBP models have a pre-formed J-shaped distal end to facilitate lead placement in the right atrial appendage. The indications for use of a RETROX lead in combination with a connected cardiac pacemaker follow those recommended in the Class I definition of the ACC/AHA Task Force Report, entitled "Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmic Devices" (JACC, Vol. 18, No. 1, July 1991:1-13.)
Device Story
Bipolar endocardial lead for permanent cardiac pacing/sensing; connects to implantable pulse generator. Features active-fixation helix tip (70% platinum/30% iridium) for tissue attachment; quadrafilar MP35N wire conductor; NuSil MED-4750 silicone rubber insulation. RX-BP models feature straight distal ends; RX-JBP models feature pre-formed J-shape for atrial appendage placement. Implanted by physicians in clinical settings. Provides electrical interface between pulse generator and heart tissue; enables pacing therapy delivery. Benefits include secure fixation and long-term pacing reliability.
Clinical Evidence
Clinical investigation included 19 patients with 31 implanted leads (14 RETROX, 17 control). Data collected from Nov 1997 to March 1998. Three anticipated adverse events for RETROX leads; four for control. No unanticipated adverse device effects reported. One patient death occurred, determined unrelated to pacing system.
Technological Characteristics
Bipolar endocardial lead; NuSil MED-4750 silicone rubber insulation; quadrafilar MP35N wire conductor; 70% platinum/30% iridium active-fixation helix tip with PVD iridium treatment. IS-1 BP connector configuration. Mechanical, electrical, and environmental testing performed per national/international standards.
Indications for Use
Indicated for patients requiring permanent pacing and sensing via single or dual-chamber implantable pulse generators. RX-BP models for ventricular or atrial placement; RX-JBP models for right atrial appendage placement.
Regulatory Classification
Identification
Temporary pacemaker electrode: A device consisting of flexible insulated electrical conductors with one end connected to an external pacemaker pulse generator and the other end applied to the heart. The device is used to transmit a pacing electrical stimulus from the pulse generator to the heart and/or to transmit the electrical signal of the heart to the pulse generator. Permanent pacemaker electrode: A device consisting of flexible insulated electrical conductors with one end connected to an implantable pacemaker pulse generator and the other end applied to the heart. The device is used to transmit a pacing electrical stimulus from the pulse generator to the heart and/or to transmit the electrical signal of the heart to the pulse generator.
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#### Safety and Effectiveness Summary 1.4
The RETROX endocardial lead is a safe and effective biopolar sense/pace lead used with implantable cardiac pacemakers when an active-fixation endocardial lead is preferred. The lead body insulation is NuSil MED-4750 silicone rubber tubing, with a conductor of quadrafilar MP35N wire.
These leads provide long-term safe and effective pacing through overall quality of design, manufacture and the surface structure of the active-fixation electrode tip. This tip is a single helically-wound fixation wire ("fixation screw") composed of 70% platinum and 30% iridium. This is the same material used for the active-fixation helix of the BIOTRONIK ELC lead. a unipolar epicardial active-fixation lead (ELC xx-UP Epicardial Lead, 510(k) #K965106, cleared January 27, 1998).
The patient-contact materials used to manufacture RETROX leads are commonly used in marketreleased leads. Additionally, corrosion studies were completed to address both long-term toxicity and durability of the physical vapor deposition (PVD) iridium treatment. The testing conducted for biocompatibility as well as extensive clinical experience confirms that iridium is safe for use as an implantable material, and analyses supporting this view have been published within technical journals. Long-term corrosion testing results substantiate that iridium is a non-toxic and durable material for use in implantable devices.
Additional validation testing results validate the safety and effectiveness of the lead design and materials used. RETROX leads undergo extensive device and component evaluations, including IS-1 BP connector testing, Si tube abrasion testing, lead tip and ring testing, complete lead mechanical, electrical and environmental testing, silicone adhesive testing, suture sleeve testing and sterile package testing. All test results were within specifications.
Based on the similarity of RETROX lead design to other market-released active fixation retractable endocardial leads, in-vitro and other validation testing performed by the manufacturer, non-U.S. and limited U.S. clinical experience, the risk to the patient in using these leads is the same as that of any implantable endocardial lead.
Potential complications resulting from the use of endocardial leads include, but are not limited to: thombosis, embolism, body rejection phenomena, cardiac tamponade, muscle/nerve stimulation, fibrillation, and infection. Lead perforation through the myocardium has been rarely observed.
BIOTRONIK, March 23, 1998
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Table 3 below summarizes some of the potential symptoms indicating a complication and possible corrective actions:
| SYMPTOM | POTENTIAL COMPLICATION | POTENTIAL CORRECTIVE ACTION |
|--------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------|
| Loss of pacing or<br>sensing | • Electrode dislodgement<br>• Lead fracture<br>• Setscrew penetration of<br>lead insulation<br>• Improper lead to<br>pacemaker connection | • Reposition lead<br>• Replace lead<br>• Replace lead<br>• Reconnect lead to pacemaker |
| Increase or decrease<br>in threshold | • Fibrotic tissue formation | • Adjust pulse generator output;<br>• Reposition lead |
Table 3 Lead Complications
#### Summary of Studies 1.5
## 1.5.1 NONCLINICAL STUDIES
Validation testing was performed to evaluate the final device as well as various manufacturing processes. All applicable national and international standards and/or criteria were evaluated. In all cases, test specifications were met. Tests were performed in the following categories:
- IS-1 BP connector testing ●
- Si tube abrasion testing .
- lead tip and ring testing .
- complete lead mechanical, electrical and environmental testing .
- stylet testing .
- . silicone adhesive testing
- suture sleeve testing .
- sterile package testing .
# 1.5.2 CLINICAL STUDIES
The Interim Clinical Investigation Summary is presented within Appendix 3. A total of 31 leads were implanted in a total of 19 patients prior to discontinuation of the study; 14 RETROX leads and 17 control (Oscor) leads were implanted. The Interim Clinical Investigation Summary presents data received between the date of study initiation (November 26, 1997) and March 15, 1998. Data from implant documentation, patient follow-up visits and out-of-service case report forms are included.
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Three anticipated adverse events have been recorded associated with the 14 study leads implanted to date; four anticipated adverse events have been recorded associated with the 17 control leads implanted to date. There have been no unanticipated adverse device effects experienced with the RETROX pacing leads as defined in 21 CFR 812.3(s); there have been no reported patient complaints regarding RETROX pacing leads.
There was one patient death reported during the clinical investigation. The patient had been randomized to control leads in both the atrium and the ventricle. This death was evaluated by the investigator and determined to be unrelated to the pacing system; relevant information is presented within the Interim Clinical Investigation Summary.
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Image /page/3/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a stylized eagle or bird-like symbol with three curved lines forming its body and wings. The text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" is arranged in a circular fashion around the symbol.
Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850
JUL 22 1998
Ms. Lauren L. Foote Christensen Manager, Regulatory Affairs Bradycardia Biotronik, Inc. 6024 Jean Road 97035-5369 Lake Oswego, OR
Re: K981083 Trade Name: Retrox RX 53-BP, Retrox RX 60-BP, Retrox RX 45-JBP, and Retrox 53-JBP Active Fixation Endocardial Leads Regulatory Class: III Product Code: DTB Dated: June 17, 1998 Received: June 19, 1998
Dear Ms. Christensen:
We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments. You may, therefore, market the device, subject to the general controls provisions of the Federal Food, Drug, and Cosmetic Act (Act). The general controls provisions of the Act include requirements for annual registration, listinq of devices, qood manufacturing practice, and labeling, and prohibitions against misbranding and adulteration.
If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval) it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with the Current Good Manufacturing Practice requirements, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic QS inspections, FDA will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory action. In addition, the
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Page 2 - Ms. Lauren L. Foote Christensen
Food and Drug Administration (FDA) may publish further announcements concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under section 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal Laws or Regulations.
On August 16, 1993 the Final Rule for Device Tracking was published in the Federal Register, pages 43442-43455 (copy enclosed). Be advised that under Section 519(e) of the Act as amended by the Safe Medical Devices Act of 1990, FDA has identified the above device as a device which requires tracking. Because the device is subject to tracking, you are required to adopt a method of tracking that follows the devices through the distribution chain and then identifies and follows the patients who receive them. The specific requirements of the regulation are found in 21 CFR 821 as described in the August 16, 1993 Federal Register beginning on page 43447.
This letter will allow you to begin marketing your device as described in your 510 (k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.
If you desire specific advice for your device on our labeling regulation (21 CFR part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4618. Additionally, for questions on the promotion and advertising of your device, please contact the Office of
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Page 3 - Ms. Lauren L. Foote Christensen
Compliance at (301) 594-4639. Also, please not the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act, may be obtained from the Division of Small Manufacturers Assistance at its toll free number (800) 638-2041 or (301) 443-6597, or at its internet address "http://www.fda.gov/cdrh/dsma/dsmamain.html".
Sincerely yours,
Thomas J. Walsh.
Thomas J. Callahan, Ph.D. Director Division of Cardiovascular, Respiratory and Neurological Devices Office of Device Evaluation Center for Devices and Radiological Health
- * -
Enclosures
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### Indications for Use
The BIOTRONIK RETROX RX 53/60-BP and RETROX RX 45/53-JBP transvenous, active fixation endocardial leads are indicated for permanent pacing and sensing. Active fixation pacing leads with a bipolar (BP) IS-1 connector configuration are designed for use in conjunction with implantable pulse generators. The leads may be used with singleor dual-chamber pacing systems.
RETROX RX-BP and RX-JBP leads differ in the shape of the distal portion of the lead. The RX-BP models are intended for placement in the ventricle or atrium and have straight distal ends. The RX-JBP models have a pre-formed J-shaped distal end to facilitate lead placement in the right atrial appendage.
The indications for use of a RETROX lead in combination with a connected cardiac pacemaker follow those recommended in the Class I definition of the ACC/AHA Task Force Report, entitled "Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmic Devices" (JACC, Vol. 18, No. 1, July 1991:1-13.)
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Learn the FDA Browser
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.