PISA Calculator
Calculate pisacalculator quickly with our cardiovascular system tool. Get results based on evidence-based formulas with clear explanations.
Formula
Meridional Stress = (0.334 x P x r) / (h x (1 + h/r))
Where P = systolic blood pressure (mmHg), r = LV internal radius (cm), h = wall thickness (cm). End-systolic stress uses end-systolic pressure and dimensions. Ventriculo-arterial coupling = Ees/Ea, where Ees = end-systolic elastance (ESP/ESV) and Ea = arterial elastance (ESP/SV).
Worked Examples
Example 1: Normal Cardiac Wall Stress Assessment
Problem: A healthy patient has SBP 120 mmHg, LVEDD 50 mm, wall thickness 10 mm, and EF 60%. Calculate wall stress parameters.
Solution: Meridional Wall Stress = (0.334 x 120 x 5.0) / (1.0 x (1 + 1.0/5.0))\n= 200.4 / 1.2 = 167.0 kdynes/cm2\n\nCircumferential Stress = (120 x 5.0) / (2 x 1.0) = 300.0 kdynes/cm2\n\nEnd-Systolic Pressure = 0.9 x 120 = 108 mmHg\nESD estimate = 5.0 x (1 - 0.36) = 3.2 cm\nEnd-Systolic Wall Stress = (0.334 x 108 x 3.2) / (1.15 x (1 + 1.15/3.2)) = 80.1 kdynes/cm2
Result: Meridional Stress: 167 | End-Systolic Stress: 80 | VA Coupling: Normal
Example 2: Dilated Cardiomyopathy Wall Stress
Problem: A heart failure patient has SBP 100 mmHg, LVEDD 70 mm, wall thickness 8 mm, and EF 25%. Calculate wall stress and coupling.
Solution: Meridional Wall Stress = (0.334 x 100 x 7.0) / (0.8 x (1 + 0.8/7.0))\n= 233.8 / 0.891 = 262.4 kdynes/cm2\n\nEnd-Systolic Pressure = 90 mmHg\nESD estimate = 7.0 x (1 - 0.15) = 5.95 cm\nESWT = 0.92 cm\nEnd-Systolic Wall Stress = markedly elevated\n\nStroke volume is reduced, arterial elastance elevated relative to LV elastance.
Result: Wall Stress: Severely Elevated | VA Coupling: Impaired | Afterload mismatch present
Frequently Asked Questions
How accurate are the results from PISA Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
Does PISA Calculator work offline?
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Can I use PISA Calculator on a mobile device?
Yes. All calculators on NovaCalculator are fully responsive and work on smartphones, tablets, and desktops. The layout adapts automatically to your screen size.
Can I use the results for professional or academic purposes?
You may use the results for reference and educational purposes. For professional reports, academic papers, or critical decisions, we recommend verifying outputs against peer-reviewed sources or consulting a qualified expert in the relevant field.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
Is PISA Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.