Online QT calculator for wide QRS (LBBB, RBBB, etc.)

This on-line QT calculator that we link to below was created by Arron Pearce. It is a work in progress — as Arron anticipates making this even more user friendly. But in the meantime — Try it out!

Click on the link:

•   Online QT calculator for wide QRS (LBBB, RBBB, etc.)

NOTE: This calculator works on an Excel spreadsheet. So after you click on the above link — You may need to download this calculator in Excel format.

Figure-1: Depending on your browser and computer — after clicking on the above link — you should get a worksheet looking something like this.
— Click on File.

Figure-2: After clicking on File — Click on Download in the menu.

Figure-3: Download the Microsoft Excel ( .xlxs ) format. And now when you open the downloaded Excel file on your computer — it should be easy to enter the heart rate and QT interval that you measure to instantly see QTc calculations in each of the 5 methods shown.
= = = = = 
For the modified QTc (when the QRS is wide) — Remember that QRS duration is in milliseconds (ie, a wide QRS = 0.15 second = 150 ms).
— The Rautaharju QTc calculation comes up immediately.
— To get the Bogossian QTc value, you'll need to enter the modified QT value into the QTc calculator on the left side of the page.

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Grauer: The fact that you will see slightly different values in the above QTc calculator conveys the lack of universal agreement on QTc calculation at different heart rates. That said — 4 of the 5 methods are generally quite close to each other (You might mentally take an average of those readings for the value you select — or pick your "favorite" among the methods).

• In our experience — We find the Bazett method potentially problematic, in that it tends to overestimate the QTc for faster heart rates — and underestimate the QTc for slower heart rates.