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Basic science
Left ventricular twist dynamics: principles and applications
  1. Carmen C Beladan,
  2. Andreea Călin,
  3. Monica Roşca,
  4. Carmen Ginghină,
  5. Bogdan A Popescu
  1. Department of Cardiology, “Carol Davila” University of Medicine and Pharmacy, “Prof Dr C C Iliescu” Institute of Cardiovascular Diseases, Bucharest, Romania
  1. Correspondence to Associate Professor Bogdan A Popescu, “Carol Davila” University of Medicine and Pharmacy—Euroecolab, “Prof Dr C C Iliescu” Institute of Cardiovascular Diseases, Sos Fundeni 258, sector 2, Bucharest 022328, Romania; bogdan.a.popescu{at}

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Physiological fundamentals of left ventricular torsion

Left ventricular anatomy

The normal left ventricular (LV) shape has been assimilated to a thick walled prolate ellipsoid with its long axis directed from apex to base.1 w1 The normal LV morphology is characterised by a high degree of regional heterogeneity. With the use of tagging magnetic resonance, a wide variation in circumferential and longitudinal radii of LV wall curvature has been shown, with a more oval shaped LV cavity in the short axis direction and more flattened LV wall towards the apex.2 In addition, a gradual thinning of the LV wall was noted toward the apex, whereas around the LV circumference, the posterolateral wall was significantly thicker than the septum.2 The law of Laplace and variations in the amount of longitudinally and circumferentially oriented fibres have been used to explain the wide variation in the thickness of the LV wall.2 w2 w3

The myocardial architecture of the left ventricle has been described in most studies as having an oblique helical fibre arrangement with a right handed helix in the subendocardial region that gradually changes into a left handed helix in the subepicardial region.3 ,4 w4–w7 Myocardial fibres in the mid LV wall are mainly oriented in the circumferential direction, whereas epicardial fibres spiral obliquely toward the apex and endocardial fibres spiral obliquely toward the base (figure 1).w8 w9 This counterdirectional helical arrangement of myocardial fibres is energetically efficient and necessary for uniform redistribution of stresses and strain in the heart, as demonstrated using mathematical models.w5

Figure 1

(A) Dissection of the human heart illustrating the progressive change in the orientation of myocardial fibres of the left ventricular (LV) wall. (a) Fibres in the superficial subepicardial layer course obliquely toward the apex in a left handed helix. (b) In the mid LV wall fibres are mainly …

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