🧵 on the Geometry of SV,...
Highlights
- 🧵 on the geometry of SV, EF and MAPSE.
1: SV is proportional to MAPSE x outer LV area. https://t.co/Iu4n3vZPVF (View Tweet)
- 2/ Left: cavity volume reduction, as function of cavity longitudinal and endocardial shortening. Right: total LV volume = cavity + myocardial volume. Given a minimally incompressible myocardium, ⬇️ in total volume = ⬇️ in cavity volume, as myocardial volume is constant.
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- 3/ EF = SV/LVEDV. In dilated ventricles, ⬆️ in LVEDV, can maintain (resting) SV, as ⬇️EF. As SV is proportional to MAPSE x diameter, MAPSE will ⬇️ in close relation to EF as diameter increases
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- 4/ In concentric ventricles, The LVEDV is ⬇️. SV is ⬇️ in proportion. (Thus there is systolic dysfunction), maintained EF is not maintained systolic function, and this is not "diastolic HF". EF is maintained due to concomitant ⬇️ in both LVEDV and SV. (View Tweet)
- 5/ LV outer diameter may be ⬆️➡️or⬇️, depending on the pattern of wall thickening, but LVIDD and LVEDV are ⬇️ in concentric geometry (per definition). As SV = MAPSE x outer diameter, MAPSE will be ⬇️ in relation to the ⬇️ SV (not EF).
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- 6/ the concept that EF is ➡️through an ⬆️ short axis function, is misunderstood geometry. In concentric ventricles FS is ➡️or ⬆️ trough ⬇️LVIDD, despite ⬇️ wall thickening.
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- 7/ EF in HFpEF is preserved by simultaneous reduction in SV and LVEDV, MAPSE is ⬇️, and there is no such thing as "compensatory short axis function. (View Tweet)