(189 days)
StrataVarius is intended for use by physicians, to non-invasively identify the Strata-type valve Performance Level (PL) setting and display that information numerically in terms of PL level and the equivalent pressure reading in millimeters of water (mm H2O). The StrataVarius allows the same user to change the pressure setting of the valve non-invasively without the need for radiographic confirmation.
Medtronic Neurosurgery's StrataVarius" System is a battery-powered, handheld instrument that senses the location and orientation of the magnet contained in PS Medical " Strata-type adjustable valves. The StrataVarius" works in conjunction with the StrataVarius Adjustment Tool to change the magnet orientation, and thus the valve Performance Level (PL) setting as determined by the Clinician. The complete system includes the StrataVarius, an Adjustment Tool, two (or more) Valve Identification Cards (Smart Cards), a Quick Reference Guide, two StrataVarius Templates, and two 1.5 volt (AA) alkaline batteries.
The Medtronic StrataVarius is a battery-powered, handheld instrument designed to non-invasively identify and display the Performance Level (PL) setting of Strata-type adjustable valves (used in CSF shunts) and the equivalent pressure reading in millimeters of water (mm H2O). It also allows users to non-invasively change the valve's pressure setting without requiring radiographic confirmation.
Here's an analysis of the acceptance criteria and the study as described in the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The provided document does not explicitly state numerical acceptance criteria in a dedicated section. However, the FDA's "substantially equivalent" determination implies that the device's performance met the criteria for equivalence to its predicate device, the Strata Adjustment Kit (K012052, K040943). The technological comparison states: "The StrataVarius is equivalent to the Strata Adjustment Kit (K012052, K040943). Substantial equivalence as demonstrated in the StrataVarius 510(k) is based on the similarities in the technological characteristics and intended use."
Given the intended use, the key performance aspects that would have been evaluated for "substantial equivalence" are:
| Acceptance Criteria (Implied) | Reported Device Performance (Implied) |
|---|---|
| Accuracy of PL Setting Identification: The ability to correctly identify and display the Strata-type valve's Performance Level (PL) setting. | Demonstrated to be accurate and consistent with the established method, as implied by FDA's substantial equivalence finding for its intended use. |
| Accuracy of Pressure Equivalent Display: The ability to accurately display the equivalent pressure reading in mm H2O corresponding to the identified PL setting. | Demonstrated to be accurate and consistent with the established method, as implied by FDA's substantial equivalence finding for its intended use. |
| Reliability of Non-Invasive Setting Change: The ability to reliably and safely change the valve's pressure setting non-invasively without requiring radiographic confirmation. | Demonstrated to reliably and safely change the valve's pressure setting non-invasively, eliminating the need for radiographic confirmation, as implied by FDA's substantial equivalence finding for its intended use. |
| Safety: No new safety concerns compared to the predicate device. | No new safety concerns identified, as implied by FDA's substantial equivalence finding. |
2. Sample Size Used for the Test Set and Data Provenance
The provided document does not specify the sample size used for any test set or the data provenance (e.g., country of origin, retrospective or prospective). The FDA decision is based on a 510(k) Pre-Market Notification, which generally focuses on demonstrating substantial equivalence to a legally marketed predicate device rather than presenting detailed clinical study results with specific sample sizes.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not provide information regarding the number of experts used, their qualifications, or how ground truth was established for any test set. For a 510(k) submission, the "ground truth" often refers to the performance of the predicate device.
4. Adjudication Method for the Test Set
The document does not describe any adjudication method used for a test set.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not mentioned. This device is not an AI-assisted diagnostic tool for human readers but rather a tool to interact with and read settings from a medical device (CSF shunt valve). Therefore, the concept of "human readers improving with AI vs. without AI assistance" is not applicable here.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
This refers to a device that performs its function directly. The StrataVarius is a standalone device in the sense that its primary function is to directly identify and display valve settings and change them non-invasively. Its performance as a mechanical/electronic tool (reading and adjusting) would be evaluated in a standalone manner, but the document does not detail the specific studies that established its standalone performance other than the general declaration of substantial equivalence.
7. The Type of Ground Truth Used
The ground truth for demonstrating the safety and effectiveness of the Medtronic StrataVarius is implicitly the established and accepted performance of its predicate device, the Strata Adjustment Kit (K012052, K040943). The StrataVarius claims "substantial equivalence" based on "similarities in the technological characteristics and intended use" to this predicate. This suggests that the ground truth for its function would be derived from the known and validated performance of the predicate in identifying and adjusting valve settings.
8. The Sample Size for the Training Set
The document does not specify a training set sample size. This type of device (a medical instrument for reading and adjusting another device) typically does not involve "training sets" in the machine learning sense. The "training" would be more akin to engineering development and testing to ensure its mechanical and electronic functions perform as intended.
9. How the Ground Truth for the Training Set Was Established
As there's no mention of a "training set" in the context of machine learning, there is no information on how ground truth for such a set was established. Development and validation of such a device would involve rigorous engineering testing, calibration against known valve settings, and verification of its ability to perform its intended functions repeatedly and accurately. The "ground truth" for these tests would be the actual physical settings of the Strata-type valves.
§ 882.5550 Central nervous system fluid shunt and components.
(a)
Identification. A central nervous system fluid shunt is a device or combination of devices used to divert fluid from the brain or other part of the central nervous system to an internal delivery site or an external receptacle for the purpose of relieving elevated intracranial pressure or fluid volume (e.g., due to hydrocephalus). Components of a central nervous system shunt include catheters, valved catheters, valves, connectors, and other accessory components intended to facilitate use of the shunt or evaluation of a patient with a shunt.(b)
Classification. Class II (performance standards).