Source: https://guthlabs.ai/docs/instruments/qtc-interval-calculator-education/implementation/

instrument implementation / implementation-contract

# QTc Interval Calculator (education) implementation

A source-bound implementation contract for QTc Interval Calculator (education); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-024

**Effect**: Computation or source lookup only

## Input and validation requirements

The zero-RR input produces undefined results and must be rejected. The specification also leaves QT/RR unit conventions and prolonged-reference thresholds insufficiently defined, allowing materially different results or an indeterminate prolonged flag.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "QT_ms": 400,
    "RR_ms": 1000
  },
  "expected_outputs": {
    "QTc_Bazett_ms": 400,
    "QTc_Fridericia_ms": 400
  },
  "working": "Convert: QT=400 ms=0.400 s; RR=1000 ms=1.000 s. Bazett: 0.400/sqrt(1.000)=0.400/1.000=0.400 s=400 ms. Fridericia: 0.400/(1.000)^(1/3)=0.400/1.000=0.400 s=400 ms."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/qtc-interval-calculator-education/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/qtc-interval-calculator-education/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/qtc-interval-calculator-education/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`