Whether you are estimating on the spot or checking a result somebody else gave you, the pisa calculator is the quickest way to get from velocity time integral (vti), vmax, vr, α angle and r to effective regurgitant orifice (ero, eroa), regurgitant volume (rvol) and mitral valve area (mva).
What Is the PISA Calculator?
The pisa calculator gives you an estimate of effective regurgitant orifice (ero, eroa), regurgitant volume (rvol) and mitral valve area (mva) based on velocity time integral (vti), vmax, vr, α angle and r.
It is a quick reference figure rather than a diagnosis, and it is most useful for tracking how a number moves over time rather than for interpreting a single reading.
How the PISA Estimate Is Worked Out
The calculation follows published reference relationships, so it is a reasonable approximation when the inputs are accurate. It assumes an average adult and does not account for individual variation.
If you are comparing two people, or the same person over a period of weeks, keep the method and the inputs identical. A change in the method can easily look like a change in the person.
What This Calculator Does Not Do
It does not diagnose anything, and it does not replace advice from a clinician. If a figure comes out at an extreme, or if it differs sharply from what you expect, that is a reason to speak to a professional rather than to adjust the inputs.
Nothing you type here is stored or sent anywhere. The whole calculation happens in your browser.
A Worked Example
Working through an example, with velocity time integral (vti) set to 10, vmax set to 5, vr set to 2, the calculator returns mitral valve area (mva) of 139.62634, and volume flow rate (vfr) of 1,256.63706, and effective regurgitant orifice (ero, eroa) of 25,132.74123. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out effective regurgitant orifice (ero, eroa)?
Enter velocity time integral (vti), vmax, vr, α angle and r. The calculator then works through the relationship and reports effective regurgitant orifice (ero, eroa), regurgitant volume (rvol) and mitral valve area (mva).
What does the pisa actually calculate?
It takes velocity time integral (vti), vmax, vr, α angle and r and converts them into effective regurgitant orifice (ero, eroa), regurgitant volume (rvol) and mitral valve area (mva) using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter velocity time integral (vti)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Does anything you type get stored?
No. The whole calculation runs inside your browser, and nothing you enter is uploaded, logged or sent anywhere.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.