PSI & Dispersion
Post-systolic index & post-systolic shortening (vendor differences)!
Calculation: 100% × (maximum post-systolic strain — end-systolic strain)/maximum post-systolic strain.
Here, as an example, with the green strain curve (next slide, septal), calculation (strain values are positive for the calculation) in an ACS: PSI= 17,5 - 15 /17,5 = 14,3%
Mechanical dispersion
Standard deviation of the time until maximal segmental contraction. Dispersion Bullseye with different times to maximal contraction in relation to the heart cycle in a patient with amyloid heart disease & AFIB, with a globally severely prolonged Dispersion with 97.6ms
As a ground rule
No mechanical Dispersion means no relevant PSS and vice versa
