# Brugada 1991 wide-QRS algorithm

Brugada

Status: LIVE
Price: $0.005 USDC
`GET /api/calc/brugada`
HTML: https://magentlab.com/docs/brugada
Markdown: https://magentlab.com/docs/brugada.md

Not a medical device. Not a diagnosis, dose, or listing recommendation.

## What it computes

Apply the Brugada 1991 four-step algorithm for regular wide-QRS tachycardia and return diagnosis vt or svt plus the step that stopped the tree.

## When to use

When an agent already has the four Brugada 1991 ECG step findings as assigned by the caller and needs the published sequential VT versus SVT result. magent does not interpret ECGs. Not Brugada syndrome and not a cardioversion order.

## When not to use

- Not a medical device.
- magent does not interpret ECGs. The caller assigns each Brugada 1991 step finding as true or false.
- This tool is the Brugada 1991 algorithm for regular wide-QRS tachycardia only. Not Brugada syndrome (coved ST), not Vereckei aVR, not RWPT, and not Sgarbossa.
- Not a cardioversion order or a rhythm diagnosis beyond the published four-step tree.

## Formula

```
VT iff no_rs_precordial or else rs_interval_gt_100 or else av_dissociation or else morphology_vt (Brugada 1991; stop at first true); else SVT
```

## Citation

[A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex](https://doi.org/10.1161/01.CIR.83.5.1649)
Brugada P, Brugada J, Mont L, Smeets J, Andries EW
Circulation. 1991;83(5):1649-1659
DOI: [10.1161/01.CIR.83.5.1649](https://doi.org/10.1161/01.CIR.83.5.1649)

## Worked example

### All four steps false

Given: `av_dissociation=false, morphology_vt=false, no_rs_precordial=false, rs_interval_gt_100=false`

1. All four Brugada 1991 steps are false as assigned by the caller
2. No step is positive, so diagnosis is svt and stopped_at is none


## Also searched as

- Brugada algorithm
- Brugada 1991
- wide complex tachycardia algorithm
- VT versus SVT
- regular wide QRS tachycardia
- RS interval 100 ms
- precordial RS complex
- AV dissociation VT
- Brugada criteria wide QRS

## Parameters

- `no_rs_precordial` (boolean, required): Step 1: absence of an RS complex in all precordial leads (Brugada 1991). true or false as assigned by the caller. true diagnoses VT and stops the tree. magent does not interpret ECGs.
- `rs_interval_gt_100` (boolean, required): Step 2: RS interval >100 ms in one precordial lead (Brugada 1991). true or false as assigned by the caller. Evaluated only when step 1 is false. magent does not measure the tracing.
- `av_dissociation` (boolean, required): Step 3: atrioventricular dissociation (Brugada 1991). true or false as assigned by the caller. Evaluated only when steps 1 and 2 are false. magent does not interpret ECGs.
- `morphology_vt` (boolean, required): Step 4: both V1–V2 and V6 morphology criteria for VT as in Brugada 1991. true or false as assigned by the caller. Evaluated only when steps 1–3 are false. magent does not interpret ECGs.

## Bulk (POST)

POST the same path with a JSON items array. The first item is the GET unit; each additional item is $0.002. Invalid items return HTTP 400 before settlement.

Method: `POST /api/calc/brugada`
Max items: 25
Price: unit_amount + extra_item_amount * (n - 1) (unit 5000 atomic, extra 2000 atomic)
Status: PREVIEW

- 1 to 25 items. Each item uses the same keys as the GET query parameters.
- POST of 1 item costs the same as GET. Lists longer than 25: chunk into multiple POSTs. Extra items still execute; do not pad dummy rows.
- The first invalid item fails the whole request (index in the 400 JSON). You are not charged.
- HTTP 200 is {count, path, items}. Each items[i] is the GET 200 body for that row.
- Catalog misses (empty matches, found=false) stay paid 200s inside that slot.
- x402 resource URL is this path plus n and body_sha256. Browsers that prefer text/html get the same paywall as GET; Pay retries POST with the same items.

Example request:

```json
{
  "items": [
    {
      "av_dissociation": "false",
      "morphology_vt": "false",
      "no_rs_precordial": "false",
      "rs_interval_gt_100": "false"
    },
    {
      "av_dissociation": "false",
      "morphology_vt": "false",
      "no_rs_precordial": "false",
      "rs_interval_gt_100": "false"
    }
  ]
}
```

Human paywall (two-item fixture): https://api.magentlab.com/paywall/bulk/brugada

Example 200:

```json
{
  "count": 2,
  "path": "/api/calc/brugada",
  "items": [
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Brugada P, Brugada J, Mont L, Smeets J, Andries EW",
        "doi": "10.1161/01.CIR.83.5.1649",
        "id": "brugada-1991",
        "pmid": "2022022",
        "source": "Circulation. 1991;83(5):1649-1659",
        "title": "A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex"
      },
      "formula": "brugada",
      "formula_expression": "VT iff no_rs_precordial or else rs_interval_gt_100 or else av_dissociation or else morphology_vt (Brugada 1991; stop at first true); else SVT",
      "criteria": [
        {
          "factor": "no_rs_precordial",
          "met": false
        },
        {
          "factor": "rs_interval_gt_100",
          "met": false
        },
        {
          "factor": "av_dissociation",
          "met": false
        },
        {
          "factor": "morphology_vt",
          "met": false
        }
      ],
      "av_dissociation": false,
      "diagnosis": "svt",
      "morphology_vt": false,
      "no_rs_precordial": false,
      "rs_interval_gt_100": false,
      "stopped_at": "none"
    },
    {
      "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
      "citation": {
        "authors": "Brugada P, Brugada J, Mont L, Smeets J, Andries EW",
        "doi": "10.1161/01.CIR.83.5.1649",
        "id": "brugada-1991",
        "pmid": "2022022",
        "source": "Circulation. 1991;83(5):1649-1659",
        "title": "A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex"
      },
      "formula": "brugada",
      "formula_expression": "VT iff no_rs_precordial or else rs_interval_gt_100 or else av_dissociation or else morphology_vt (Brugada 1991; stop at first true); else SVT",
      "criteria": [
        {
          "factor": "no_rs_precordial",
          "met": false
        },
        {
          "factor": "rs_interval_gt_100",
          "met": false
        },
        {
          "factor": "av_dissociation",
          "met": false
        },
        {
          "factor": "morphology_vt",
          "met": false
        }
      ],
      "av_dissociation": false,
      "diagnosis": "svt",
      "morphology_vt": false,
      "no_rs_precordial": false,
      "rs_interval_gt_100": false,
      "stopped_at": "none"
    }
  ]
}
```

## Response fields

- `formula` (string): brugada
- `formula_expression` (string): Brugada 1991 four-step sequential tree
- `diagnosis` (string): vt if any step is the first true finding; otherwise svt. Not a diagnosis of Brugada syndrome.
- `stopped_at` (string): First positive step: no_rs_precordial, rs_interval_gt_100, av_dissociation, or morphology_vt; none when all four are false
- `no_rs_precordial` (boolean): Echo of the caller-assigned step 1 flag
- `rs_interval_gt_100` (boolean): Echo of the caller-assigned step 2 flag
- `av_dissociation` (boolean): Echo of the caller-assigned step 3 flag
- `morphology_vt` (boolean): Echo of the caller-assigned step 4 flag
- `criteria` (array): Per-step rows with factor and met; met echoes that caller-assigned flag
- `citation` (object): Brugada et al. Circulation 1991 citation
- `disclaimer` (string): Not-a-device notice

## Example JSON

Frozen fixture. Not a live lookup.

```json
{
  "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
  "citation": {
    "authors": "Brugada P, Brugada J, Mont L, Smeets J, Andries EW",
    "doi": "10.1161/01.CIR.83.5.1649",
    "id": "brugada-1991",
    "pmid": "2022022",
    "source": "Circulation. 1991;83(5):1649-1659",
    "title": "A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex"
  },
  "formula": "brugada",
  "formula_expression": "VT iff no_rs_precordial or else rs_interval_gt_100 or else av_dissociation or else morphology_vt (Brugada 1991; stop at first true); else SVT",
  "criteria": [
    {
      "factor": "no_rs_precordial",
      "met": false
    },
    {
      "factor": "rs_interval_gt_100",
      "met": false
    },
    {
      "factor": "av_dissociation",
      "met": false
    },
    {
      "factor": "morphology_vt",
      "met": false
    }
  ],
  "av_dissociation": false,
  "diagnosis": "svt",
  "morphology_vt": false,
  "no_rs_precordial": false,
  "rs_interval_gt_100": false,
  "stopped_at": "none"
}
```

## Errors

- HTTP 400 `invalid_flag`: boolean clinical flags must be true or false Returned before settlement; you are not charged.
- HTTP 400 `invalid_brugada`: each Brugada 1991 step must be true or false. Returned before settlement; you are not charged.
- HTTP 400 `invalid_items`: POST body must be a JSON object with only an items array Returned before settlement; you are not charged.
- HTTP 400 `invalid_item_count`: items must be an array of 1 to 25 objects Returned before settlement; you are not charged.
- HTTP 400 `invalid_item`: each items entry must be a JSON object Returned before settlement; you are not charged.

Shared HTTP 402 and 503: https://magentlab.com/docs/payments

## Related tools

- [Sgarbossa](https://magentlab.com/docs/sgarbossa) — Sum the three Sgarbossa 1996 GUSTO-1 ECG criteria in left bundle-branch block and return whether the total is ≥3.
- [QTc](https://magentlab.com/docs/qtc) — Compute heart-rate-corrected QT using Bazett or Fridericia. The formula argument is required.

## Payment

Unpaid requests return HTTP 402 even if query parameters or POST items are missing or invalid, so CDP and agents can index the path. After a PAYMENT-SIGNATURE, invalid params return HTTP 400 JSON before settlement. magent does not charge. Fix the params, then request a new 402 quote for that complete URL. Catalog misses (empty matches, found=false) are valid paid 200s.

- GET the tool with Accept: application/json (do not send Accept: text/html unless you want the human paywall).
- HTTP 402 means you have not paid. Decode the base64 PAYMENT-REQUIRED header. HTTP 503 is not a new quote.
- Sign accepts[0] (exact, EIP-3009) with validBefore = now + maxTimeoutSeconds (600 seconds), or accepts[1] (batch-settlement deposit/voucher) on product GET. Ping and POST {items} stay exact. Magent retries transient facilitator 429/5xx before answering.
- Retry the same URL with PAYMENT-SIGNATURE (base64 JSON of accepted and payload). Magent attaches canonical extensions.bazaar on CDP verify/settle; echoing 402 bazaar is optional.
- Success is HTTP 200 JSON plus PAYMENT-RESPONSE. exact settles before the tool. batch-settlement verifies (and deposit-settles) before the tool and commits the charge after HTTP 2xx. HTTP 503: retry the same PAYMENT-SIGNATURE. Mint a new exact nonce only after a new HTTP 402.

- offered `exact` on eip155:8453: Fixed-price USDC on Base. The buyer authorizes the advertised amount (EIP-3009). magent settles before the tool runs (paymentFlow upfront). extra.assetTransferMethod=eip3009 extra.paymentFlow=upfront.
- offered `batch-settlement` on eip155:8453: Payment-channel vouchers claimed later in batches. Exact stays accepts[0]. Same-path POST {items} is still exact. extra.assetTransferMethod=eip3009 extra.paymentFlow=authorization.

- not offered `upto`: Not offered. Usage-based: buyer authorizes a ceiling, seller settles the actual amount after work. Reserved for a future metered tool. Not for current calculators or code search.

Same-path POST {items} is still scheme exact: one EIP-3009 authorization for GET unit plus $0.002 per extra item. That is not x402 batch-settlement (payment channels / vouchers).

Shared HTTP 402 and 503 table: https://magentlab.com/docs/payments

Stdio MCP (one process per host): https://magentlab.com/docs/mcp

## Guarantees

- HTTP 402 is unpaid, including a missing query. After PAYMENT-SIGNATURE, invalid parameters return HTTP 400 before settlement. You are not charged. HTTP 402 never includes the tool JSON.
- exact: settlement finishes before the tool (paymentFlow upfront). batch-settlement: verify/deposit before the tool; chargedCumulativeAmount commits after HTTP 2xx. Uncertain or failed settlement fails closed (HTTP 503). Retry the same PAYMENT-SIGNATURE.
- HTTP 402 is unpaid only. Do not sign a second authorization because of a 503.
- Execution is timeout-bounded and concurrency-capped.
- Calculator inputs are stored encrypted for allowlisted operators (Magent Console). They are not in public logs, SSH lookups, catalog, or rollups. Request logs store path without query.