Regional left ventricular rotation and back-rotation in patients with reverse septal curvature hypertrophic cardiomyopathy.
ABSTRACT AIMS: This study sought to investigate regional left ventricular (LV) rotation in patients with hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: The study comprised 44 patients with HCM with a typical reverse septal curvature (age 40 ± 14 years, 33 men) and 44 healthy volunteers (age 39 ± 14 years, 32 men) in whom LV rotation could be assessed at the basal and apical LV level with speckle-tracking echocardiography, using the QLAB Advanced Quantification Software version 6.0 (Philips, Best, The Netherlands). In HCM patients, lower values of initial counter-clockwise rotation at the basal LV level (1.5 ± 1.2 vs. 0.6 ± 0.9°, P < 0.001) were seen, in particular in the septal segment (1.7 ± 1.6 vs. 0.4 ± 0.7°, P < 0.001). After this period, the direction of rotation changed to clockwise with a peak basal rotation of -4.8 ± 2.0° in controls vs. -6.1 ± 2.5° in HCM patients (P < 0.05). Peak basal rotation in HCM patients was in particular higher in the anterior (-6.6 ± 3.0 vs. -4.4 ± 2.4°, P < 0.01) and septal (-5.4 ± 2.6 vs. -3.9 ± 1.9°, P < 0.05) segments. The normalized (corrected for peak basal rotation) global back-rotation rate was lower in HCM patients (4.1 ± 3.1 vs. 6.3 ± 4.9 s(-1), P < 0.05), in particular driven by a lower rate in the septal segment (3.8 ± 2.6 vs. 6.4 ± 4.8 s(-1), P < 0.01). At the apical level, changes in rotation and back-rotation were more homogeneous. CONCLUSION: Changes in rotation and back-rotation at the LV basal level in HCM patients are mainly caused by regional changes in the basal septal and anterior segments, the segments mostly involved in the hypertrophic process.
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ABSTRACT: Previous studies suggest that intramural myocardial architecture is arranged to maximize the efficiency of contraction. To examine the topography of the cardiac ventricles for a possible similar functional economy, measurements were made of the heart weight and ventricular wall curvature, thickness, chamber volumes and axial diameters in 80 hearts, with and without ventricular dilatation or hypertrophy, or both, that had normal coronary arteries and no myocardial lesions. Hearts in various positions of contraction were studied after postmortem arteriography and fixation in distension. Indexes of curvature-thickness were calculated from the measurements using the Laplace relation. The ventricles consist of three mutually intersecting curved partitions, right and left free walls and interventricular septum, which are segments of prolate spheroids. The septum usually curves so as to function as part of the left ventricle but is thinner and flatter than the free wall. Indexes of curvature-thickness showed that in the distended position ventricles are more globular and thin-walled; in the contracted position they are more cylindrical and thicker. The left ventricular free wall index showed greater change between distension and contraction than the other components.The results suggest that ventricular configuration is a compromise between a spherical shape that would need the least energy for diastolic ventricular filling and a tubular shape that would permit maximal conversion of systolic myocardial muscle cell tension into cavitary pressure increase. Ventricular topography probably develops as that geometry that requires the minimal energy expenditure in the overall economy of the circulation. Clinical determination of curvature-thickness indexes, similar to the postmortem indexes studied here, may find practical implementation in the assessment of cardiac diseases with two dimensional echocardiography and radionuclide imaging.The American Journal of Cardiology 05/1978; 41(4):646-54. · 3.21 Impact Factor
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ABSTRACT: In order to investigate the possibility of regional variation of ventricular structure, 25 normal postmortem human hearts were studied by inspection of cavity shape and subepicardial fibre orientation, by dissection, and by the histology of sections in two orthogonal planes. Ventricular architecture was complex. Inlet and outlet long axes were separated by 30 degrees in the left ventricle. In the right the corresponding figure was 90 degrees. The thickest part of the left ventricular wall was at the base. At the apex there was potential endo- and epicardial continuity. Left ventricular cavity shape departed significantly from any simple geometric figure, there being, consistently, regions of both positive and negative curvature on the diaphragmatic aspect. The presence of trabeculae caused considerable variation in wall thickness. Striking variation was found in the arrangement of subepicardial muscle fibres. Most pronounced was the contrast between the longitudinal arrangement of fibres observed on the oblique margin and the circumferential arrangement of those on the acute. On the diaphragmatic surface of the left ventricle, fibres near the crux and apex ran circumferentially while those between ran obliquely; those on the diaphragmatic surface of the right ventricle also ran circumferentially. Deeper in the myocardium the arrangement was simpler. In the mid-wall of the left ventricle fibres were circumferential, best developed towards the base and in the upper part of the septum. Near the apex of the left ventricle and in the mid-wall of the right ventricle such fibres were sparse. The subendocardial region consisted of longitudinally directed fibres forming the trabeculae and papillary muscles, while fibres deep to and between the trabeculae coursed more obliquely. These findings were confirmed by histology. Models based on uniform myocardial fibre structure cannot explain wall movement in normal subjects, and are likely to have significant limitations if used to investigated left ventricular function in disease.Heart 04/1981; 45(3):248-63.
Article: Mechanics of ventricular torsion.[Show abstract] [Hide abstract]
ABSTRACT: Recent research suggests that left ventricular torsion is an important indicator of cardiac function. We used two theoretical models to study the mechanics of this phenomenon: a compressible cylinder and an incompressible ellipsoid of revolution. The analyses of both models account for large- strain passive and active material behavior, with a muscle fiber angle that varies linearly from endocardium to epicardium. Relative to the end- diastolic configuration, the predicted torsion exhibits several experimentally observed features, including a peak near end systole, rapid untwisting during isovolumic relaxation, and increased twist near the apex. The magnitude of the twist is sensitive to the fiber architecture, the ventricular geometry, and the compressibility and contractility of the myocardium. In particular, the model predicts that the systolic twist increases with increasing compressibility, contractility, and wall thickness, while it decreases with increasing cavity volume. The peak twist approximately doubles (from about 0.02 to 0.04 rad cm(-1)) with a doubling of myocardial compressibility or with a change in the endocardial/epicardial muscle fiber angles from 90/ -90 degrees to 60/ -60 degrees. The twist is less sensitive to changes in contractility and ventricular geometry. These findings provide a basis for interpreting measurements of ventricular torsion in the clinical setting.Journal of Biomechanics 07/1996; 29(6):745-52. · 2.72 Impact Factor