Mayo Clinic RBBB QTc Calculator

Mayo Clinic RBBB QTc Formula:

\[ QTc = \frac{QT - 0.5 \times (QRS - 120)}{\sqrt{RR}} \]

Corrected QT (QTc):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What Is The Mayo Clinic RBBB QTc Calculator?

The Mayo Clinic RBBB QTc Calculator is a specialized tool designed to accurately calculate the corrected QT interval (QTc) in patients with Right Bundle Branch Block (RBBB). It accounts for the prolonged QRS duration by adjusting the QT measurement before applying Bazett's correction formula.

2. How Does The Calculator Work?

The calculator uses the Mayo Clinic RBBB QTc formula:

\[ QTc = \frac{QT - 0.5 \times (QRS - 120)}{\sqrt{RR}} \]

Where:

\( QT \) — Measured QT interval (ms)
\( QRS \) — QRS duration (ms)
\( RR \) — RR interval (s) = 60 / HR
\( HR \) — Heart rate (bpm)

Explanation: The formula first modifies the QT interval by subtracting 50% of the excess QRS duration over 120 ms, then applies Bazett's formula to correct for heart rate.

3. Importance Of QTc Calculation In RBBB

Details: Accurate QTc calculation is essential in RBBB patients to avoid overestimation of QT prolongation, which could lead to misdiagnosis of long QT syndrome and inappropriate treatment decisions.

4. Using The Calculator

Tips: Enter QT and QRS intervals in milliseconds, heart rate in beats per minute. All values must be positive numbers. The calculator will compute the corrected QT interval specific for RBBB.

5. Frequently Asked Questions (FAQ)

Q1: Why is special QT correction needed for RBBB?
A: Standard QT correction formulas overestimate QT prolongation in RBBB due to the prolonged QRS duration. The Mayo Clinic formula provides more accurate correction.

Q2: What is the clinical significance of QTc prolongation?
A: Prolonged QTc is associated with increased risk of ventricular arrhythmias, particularly torsades de pointes, and sudden cardiac death.

Q3: When should this calculator be used?
A: This calculator should be used specifically for patients with Right Bundle Branch Block to obtain accurate QTc measurements.

Q4: Are there limitations to this formula?
A: The formula is specifically validated for RBBB and may not be appropriate for other conduction abnormalities or complex arrhythmias.

Q5: What are normal QTc values?
A: Normal QTc is typically <450 ms for men and <460 ms for women. Values above these thresholds may indicate prolonged QT interval.