Myocardial mechanics — the left ventricle
Contractile cardiomyocytes are connected and build up the majority of the myocardium ➜ interconnected network ➜ multilayer architecture with contraction & relaxation
3 layers but no strict borders ➜ subendocardial (rightward oriented), mid-wall & subepicardial (leftward oriented)
1 outer helix, one inner helix & mid-wall myocardium
Normal contraction in 4D multi-slice
Normal contraction in 4D multi-slice
Subepicardial — leftward-oriented helical fibres, 25% of the myocardial wall ➜ Apex “torsion” relative to the base of the heart
Midwall — 53-59% of the myocardial wall thickness with a larger extent because of ageing, circumferential fibres parallel to the mitral valve — radial contraction
Subendocardial — thin, < 20% of the myocardial wall, rightward-oriented helical fibres, longitudinal function, and rotation
HFrEF with WMA septal & contrast without a specified preset
HFrEF with WMA septal & contrast without a specified preset
Nakatani S, 2011
Torrent Guasp Model — 1 muscle band (helical & circumferential fibres)
1 basal loop, 2 segments (ascending epicardial & descending endocardial), and an apical loop with a fixed apex
Descending endocardial = longitudinal shortening (+ apex rotation clockwise & heart base counterclockwise).
Apex & base rotation is mirror-inverted in systole & diastole.
During the IVRT & IVCT apex & base rotate in the same direction
3D data set — resting study
3D data set — resting study
Gaus 2004, Di Salvo et al., J Cardiovasc Echo, 2015
Systole: apical counterclockwise (descending segment subendocardial); vs stronger (greater radius) ascending subepicardial segment; less rotation at the base of the heart clockwise
Diastole: Apex rotates clockwise, the base counterclockwise
IVC (isovolumic contraction): Base & apex rotate counterclockwise (circumferential contraction, ascending segment without contraction but with elongation & narrowing of the LV)
IVR (isovolumic relaxation): Base & apex rotate clockwise (no contraction descending & circumferential (recoil), ascending only little contraction (LV elongates & stretches (a little bit))
3D adenosine-stress echo
4D STEMI (LAD)
3D adenosine-stress echo
4D STEMI (LAD)
Time in between contraction of the ascending and descending segments is 80-90 ms — shortening = post systolic shortening leads therefore to ineffective filling (descending fibres shorten persistently during diastole) = 50% of „untwisting“ inefficient.
Ischemic CMP, severely reduced LV-function, severely dilated LV, apical WMA
Ischemic CMP, severely reduced LV-function, severely dilated LV, apical WMA
Di Salvo et al., J Cardiovasc Echo, 2015
