The role of longitudinally and circumferentially oriented fibres in left ventricular wall motion was examined by digitising echocardiograms of the mitral ring (whose motion reflects long axis change) and of the standard minor axis in 36 healthy individuals, 36 patients with coronary artery disease, 16 with left ventricular hypertrophy, 44 with mitral valve disease (24 of whom had undergone mitral valve replacement). In the controls long axis shortening significantly preceded minor axis shortening (mean (1 SD) difference 25 (40) ms) so that the minor axis increased more during isovolumic contraction (0 25 v 0 09 cm), indicating that the left ventricle became more spherical. Changes in the long and short axes were synchronous at end ejection and in early diastole in the controls. Epicardial excursion preceded endocardial excursion by 50 (20) ms at its peak. These time relations were consistently disturbed in all patient groups, irrespective of the extent of fractional shortening of the minor axis. The onset of long axis shortening was delayed, and this was often associated with premature shortening of the minor axis, the normal spherical shape change during isovolumic contraction was lost, and peak epicardial and endocardial changes became more synchronous. In patients with coronary disease these changes are the expected consequence of ischaemic injury to longitudinally orientated subendocardial fibres. In left ventricular hypertrophy their presence consistently showed systolic dysfunction when orthodox measures were still normal. They were more pronounced after mitral valve replacement when the papillary muscles had been sectioned; long axis shortening was reduced during systole and prolonged into early diastole, while normal shortening of the minor axis was maintained only by abnormal epicardial excursion.Relations between long and short axis motion in healthy individuals are characteristic, and their loss is an early index of systolic ventricular disease. These disturbances precede changes in orthodox measures such as fractional shortening or peak velocity of circumferential fibre shortening.Anatomical studies'2 have shown longitudinal as well as circumferential fibres with a continuous variation in fibre angle across the left ventricular wall. The function of these longitudinal fibres has not been extensively studied. Because effective ventricular function during ejection and filling is likely to depend upon the coordinated action of all myocardial layers, we set out to study the timing and extent of changes in the long axis, comparing them with those of the minor axis in healthy controls and those with left ventricular disease. In addition, we investigated patients after mitral valve replacement where a component of the longitudinal fibres (the papillary muscles) had been sectioned. Patients and methods CONTROLS AND PATIENTSCross sectionally guided M mode echocardiograms were recorded and analysed in 36 patients with coronary artery disease, 16 with left ventricular hypertrophy, 44 patients with mitr...
Objective-To investigate the gross arrangement of the principal muscular bundles of the two atria, and to suggest how it may contribute to contraction and spread of atrial excitation. Design-A prospective analysis based on anatomical examination of adult human hearts. Setting-A national heart and lung institute and a tertiary referral centre for cardiac disease. Material-9 normal postmortem human hearts. Methods-Dissection of atrial muscles with macrophotography. Results-The atrial walls consist of circumferential and longitudinal muscular bundles, the former being arranged at the base of the atria with the latter predominating in the parietal walls. The muscular bundles in the right atrium are larger than those in the left. The main muscles forming the right atrial wall are the terminal crest and terminal pectinate muscles. The terminal crest, the most obvious muscle, is arranged longitudinally with its pectinate muscles connecting to the musculature of the atrioventricular vestibule. No structure resembling the terminal crest is seen in the left atrium. Instead the left atrial wall is composed of intermingled series of muscles, chief of these being the interatrial band and the septoatrial bundle. The former is arranged circumferentially at the atrial base, while the latter is mainly longitudinal. The wall of the right atrium is not of uniform thickness because of the presence of the terminal crest and its pectinate muscles on its internal surface. By contrast, the left atrial wall is much more uniform and its average thickness is greater than that of the right atrium. The rim of the oval fossa is the most important muscular structure on the septal surface and is formed by the infolded atrial walls. The other principal muscles of the atria attach to it, so that the rim provides mechanical support for overall movement of the atrial walls. Comparison of the gross arrangement of the atrial musculature with earlier echocardiographic measurements showed that this arrangement of the muscle explains movement of the atrioventricular ring and overall atrial contraction, and provides a suitable substrate for preferential conduction. Conclusion-The anatomical features of the atrial musculature explain the known facts concerning atrial contraction and preferential conduction. (Br HeartJ7 1995;73:559-565)
The determinants of aortic pressure and flow are generally studied using impedance methods, the results of which indicate that reflected waves are important, particularly during aortic flow deceleration. An alternative analysis of measured aortic pressure and velocity, using the method of characteristics to calculate the energy flux per unit area of the waves, suggests a different conclusion. We suggest that aortic deceleration is caused by a discrete expansion wave propagating from the left ventricle, and that energy thus recovered by the ventricle may be coupled to early filling of the ventricle.
Values of QRS duration are unimodally distributed in patients with dilated cardiomyopathy, without evidence of a discrete group of patients with left bundle branch block. Prolonged QRS duration reduces peak +dP/dt, prolongs overall duration of the pressure pulse, the time to peak +dP/dt, and relaxation time. Duration of QRS must therefore be taken into account in assessing standard measurements of myocardial function in patients with dilated cardiomyopathy.
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