QTJTCalculator

QTJT Calculator is an educational calculator designed to streamline QTc and JTc interpretation, especially when QRS duration may affect repolarization assessment.

The app allows users to enter sex, QT interval, optional QRS duration, and either heart rate or RR interval. If heart rate is entered, RR is automatically calculated; if RR is entered, heart rate is automatically calculated. The app then applies a structured correction workflow and displays calculated outputs in a clean, easy-to-read interface.

Key features include:

• Automatic HR ↔ RR conversion
• QTc calculation using Hodges and Framingham correction
• Bogossian QTm adjustment when QRS is wide
• Rautaharju bivariate QTc correction using QT, RR, QRS, and sex-specific constants
• JTc calculation using Hodges and Framingham correction when QRS ≥ 110 ms
• Clear abnormal-value highlighting
• Instructions and formula reference built into the app
• For educational use only

This app is based on correction methods discussed in the literature for QT assessment in the setting of ventricular conduction delay or pacing. When QRS is widened, the measured QT interval may appear prolonged because the QRS duration itself contributes to QT length. QT/JT Correction helps demonstrate practical approaches to adjusting for this issue, including QTm modification and JT-based correction.

The app also avoids reliance on the Bazett correction, which can overestimate QTc at higher heart rates and underestimate QTc at lower heart rates. Instead, it focuses on Hodges, Framingham, Bogossian, and Rautaharju-based approaches.

The app is intended for educational purposes only. It is not a medical device, does not provide clinical recommendations, and should not be used for diagnosis, treatment, medication decisions, or patient care. Results should always be interpreted in the context of clinical judgment, institutional guidance, and validated clinical references.