Endomysium in left ventricle

Abstract

Objective-To assess whether the size of the cytosine-thymine-guanine (CTG) expansion mutation in myotonic dystrophy predicts progression of conduction system disease and cardiac events. Design-Longitudinal study involving ECG and clinical follow up over (mean (SD)) 4.8 (1.8) and 6.2 (1.9) years, respectively, of patients stratified by CTG expansion size (E0 to E4). Patients-73 adult patients under annual review in a regional myotonic dystrophy clinic. Patients were grouped into E0/E1 (n = 25), E2 (n = 34), and E3/E4 (n = 14). Results-The proportion of patients with a QRS complex > 100 ms at baseline increased with the size of the CTG expansion (EO/E1, 4%; E2, 12%; E3/E4, 36%; p = 0.02). This trend was more pronounced at follow up (E0/E1, 4%; E2, 21%; E3/E4, 57%; p = 0.0004). The rate of widening of the QRS complex (ms/year) was similarly related to the size of the mutation (EO/E1, 0.4 (1.3); E2, 1.4 (2.5); E3/E4, 1.5 (1.6); p = 0.04). First degree atrioventricular block was present in 23% of patients at baseline and 34% at follow up, with no significant relation to expansion size. Seven patients suVered a cardiac event during follow up (sudden death in two, permanent pacemaker insertion in three, chronic atrial arrhythmia in two), of whom six were in CTG expansion group E2 or greater. Patients who experienced a cardiac event during follow up had more rapid rates of PR interval increase (9.9 (11.1) v 1.6 (2.9) ms/year; p = 0.008) and a trend to greater QRS complex widening (3.6 (4.5) v 0.9 (1.5) ms/year; p = 0.06) than those who did not. Conclusions-Larger CTG expansions are associated with a higher rate of conduction disease progression and a trend to increased risk of cardiac events in myotonic dystrophy. (Heart 2001;86:411-416)

Myocardial tissue engineering: the extracellular matrix☆

“…With each excitationcontraction cycle the physical forces that are developed on the cellular level have to congregate to develop the macroscopic contraction force of the heart. This process of upscale merging of physical forces is mediated by the delicate arrangement of the cardiac ECM [11]. As a result a significant dynamic change of the three-dimensional arrangement of all active and passive myocardial elements takes place accordingly.…”

Cardiac Mechanics Revisited

“…The extracellular collagen matrix of the myocardium is an important scaffold in maintaining muscle fiber alignment, ventricular shape, and size. It forms a spiral fibrillar structure of endomysial collagen 47 to support a spatial distribution of myocytes and myofibers that ensheathes 48 the adjacent 3-dimensional reciprocal spiral arrangement pattern of muscle structure. Many anatomic dissections of the musculature of the conical heart ventricles over the past 500 years 8 confirm that the clockwise oblique fibers of the surface epicardial layer and counterclockwise oblique subendocardial layer fibers meet at the apical vortex and that a transverse layer surrounds the LV base.…”

Leonardo da Vinci's flights of the mind must continue: cardiac architecture and the fundamental relation of form and function revisited

“…The helical pathway of the electrical activation is not the direct evidence for the above-mentioned coil pattern of myocardial fibers but it raises a challenging question. A three-dimensional image of the arrangement of endomysial collagen studied by special scanning electron microscopy after sodium hydroxide maceration in non-contracted rabbit heart (free wall of the left ventricle) was published in Images in Cardiology, Heart 2001 [68]. This method of maceration allowed the isolation of collagen fibers, the elimination of all other tissue elements, and the preservation of endomysial structure and position.…”