🧵Left Atrial Strain. 1/...
Highlights
- 🧵Left atrial strain. 1/ Left atrial strain is the deformation of the left atrium, measured throughout the heart cycle. There are three phases as recommended by present guidelines: LA reservoir strain, LA conduit strain and LA contractile strain as shown in the figure
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- 2/ But what does these measures signify physiologically? Taking a look at the atrial and ventricular strain curves from the same ventricle is interesting. As we see, the two sets of curves are reciprocal.
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- 3/ this of course signifies a great degree of interdependency, as shown: https://t.co/rpftZxPjpW (View Tweet)
- 4/ This, of course is because both are reflections of the mitral annulus motion, the long axis function of the heart. The mitral annular motion from the same patient, shown by TDI, has the same shape.
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- 5/ Systolic ventricular strain is AV-plane motion with LV wall length as denominator. The mitral annular-plane motion (MAPSE) is the main determinant of the global LV systolic function https://t.co/LlRdLs1fb0 and can also be derved by M-mode (still same pat.) (View Tweet)
- 6/ Atrial strain, is Mitral annular plane motion with atrial wall length as denominator. Atrial reservoir strain is the atrial expansion during ventricular ejection, the energy is provided by the ventricular myocardium, although the atrium is expanded. https://t.co/M8Rzq6FWeV (View Tweet)
- 7/ This means that reduced LA reservoir strain may just as well be due to reduced LV systolic function (MAPSE is reduced both in HFrEF and HFpEF ), as reduced LV systolic function is also a cause for increased LA pressure.
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- 8/ LA reservoir strain = MAPSE / LA wall length, and ↓ LV function is a confounder. ↑ LA size is also a factor in ↓ LA reservoir strain, but causality may be reversed, ↑ LAP may give ↑ LA size which gives ↓ LA reservoir strain. (View Tweet)
- 9/ And of course confounding and reverse causality becomes even more tangled in AF. AF in itself →↑LA size, and both HF and ↑ LAP → ↑ LA size, which → ↑ risk of AF. At some later time, I'll take a closer look at the LA "conduit strain"
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