Left ventricular mechanics in dilated cardiomyopathy

Laskey, Warren K.; Sutton, Martin St. John; Zeevi, Gary R.; Hirshfeld, John W.; Reichek, Nathaniel

doi:10.1016/0002-9149(84)90261-3

Cited by 62 publications

(17 citation statements)

References 26 publications

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“…Judging from the present data and others in the literature [1, 8,17,18], lengths are usually less affected by disease and are more predictable than are diameters . It is reasonable to advance the working hy- poth that the equations which summarize the present data might be useful for predicting long axes, either to identify disease-related peculiarities when long axes are measured or to estimate volumes when long axes are not measured .…”

Section: Use Of Correlations For Predicting Long Axissupporting

confidence: 74%

“…Thus, the coefficients of the relations appear to be somewhat age dependent . This is confirmed by the fact that, in adults of all ages with a variety of diseases [8,17,18], the rela- Using this equation to predict Le,/Des , the mean and standard deviation of (predicted LeS/DC ,)/(observed LJDC4) were 1 .00 ± 0 .06.…”

Section: Relations Between Axis Ratios and Dilationmentioning

confidence: 69%

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Left-ventricular cavity dimensions in children with normal and dilated hearts

et al. 1988

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Studies were carried out to find how left-ventricular length and length/diameter ratio relate to body size and degree of dilation. By use of M-mode and two-dimensional echocardiography, diastolic cavity long axis (Led), diastolic cavity diameter (Ded), systolic cavity long axis (Les), systolic cavity diameter (Des), fractional L shortening (SFL), and fractional D shortening (SFD) were measured in children, adolescents, and young adults between two and 23 years of age, with body-surface area (BSA) between 0.5 and 2.1 m2 and with a variety of volume loads and SFD values. In normal subjects, Led/Ded was about 1.9. Regardless of age and pathology (in this age range), Led correlated consistently with BSA (Led = 3.9 + 3.2 BSA), indicating that the long axis changes rather little with pathological dilation. A plot of Led/Ded vs BSA/D2ed (in m2/cm2) formed a straight-line relation: Led/Ded = 0.77 + 16.4 BSA/D2ed. Similar relations were found for end-systolic dimensions. End-systolic L/D ratio exceeded end-diastolic L/D ratio to a degree that depended on both end-diastolic L/D ratio and SFD:Les/Des = Led/Ded + (0.22 + 2.67 Led/Ded)(SFD)2. Relations like these may be useful in the interpretation of echocardiographic images. The results suggest that left-ventricular L/D ratio may be influenced by myocardial anisotropy (dominance of hoop over meridional fiber orientation tending to promote prolate shape especially during systole) and external factors that antagonize extension of the long axis.

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Section: Use Of Correlations For Predicting Long Axissupporting

confidence: 74%

Section: Relations Between Axis Ratios and Dilationmentioning

confidence: 69%

Left-ventricular cavity dimensions in children with normal and dilated hearts

et al. 1988

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“…Our data also suggest that the displacement of the mitral leaflet coaptation in the LV cavity is due to the more spherical shape of the LV during exercise, which in turn could be due to the lesser ability of patients with severe exercise limitation to vasodilate peripherally to decrease afterload and hence LV systolic wall stress. 28 Failure to vasodilate peripherally may also contribute independently to limit exercise capacity by preventing the normal increase in peripheral muscle blood flow. Finally, we believed we could reasonably exclude any significant contribution of ischemia to the present results because none of our patients, including those with an ischemic heart disease, experienced anginal symptoms or developed objective signs of inducible ischemia during exercise.…”

Section: Mechanisms Of Exercise-induced Mrmentioning

confidence: 99%

Contribution of Exercise-Induced Mitral Regurgitation to Exercise Stroke Volume and Exercise Capacity in Patients With Left Ventricular Systolic Dysfunction

et al. 2002

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Background-Functional mitral regurgitation (MR) is common in patients with heart failure and left ventricular (LV) dysfunction, and its severity may vary over time, depending primarily on the loading conditions. Because dynamic changes in the severity of functional MR may affect forward stroke volume, we hypothesized that exercise-induced changes in MR severity influence the stroke volume response of patients with LV dysfunction to exercise, and hence their exercise capacity. Methods and Results-Heart failure patients (nϭ25; mean age 53Ϯ12 years) with LV dysfunction underwent dynamic bicycle exercise at steady-state levels of 30%, 60%, and 90% of predetermined peak V O 2 . During each exercise level, right heart pressures, cardiac output, V O 2 , and MR severity were measured simultaneously. During exercise, MR severity, as evaluated by the ratio of MR jet over left atrium area, increased from 15Ϯ8% to 33Ϯ15%. Peak V O 2 , exercise-induced changes in stroke volume, and those in capillary wedge pressure correlated with the changes in MR (rϭϪ0.55, Ϫ0.87, and 0.62, respectively, PϽ0.01). The changes in MR severity also correlated with those in end-diastolic (rϭϪ0.75, PϽ0.01) and end-systolic (rϭϪ0.72, PϽ0.01) sphericity indexes and those in the coaptation distance (rϭ0.86, PϽ0.01). Conclusions-Our data indicate that in patients with LV dysfunction, exercise-induced changes in MR severity limit the stroke volume adaptation during exercise and therefore contribute to limitation of exercise capacity.

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“…In humans with valve diseases, Mirsky et al [19] found an inverse relation between systolic performance and estimated systolic stiffness, since reduced systolic performance was associated with increased estimated dead space. In humans with dilated cardiomyopathy, Laskey et al [20] observed reduced systolic performance (shortening fraction half of normal) and increased systolic stiffness (unloaded length 1.87 of normal, raw stress-length slope 0.63 of normal, and stiffness therefore 1.18 of normal). As anticipated by Suga et al [14], systolic stiffness is not a reliable index of systolic vigor because dead space is a variable, not a valid expression of chamber size.…”

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confidence: 99%

Estimation of left-ventricular systolic performance and its determinants in man from pressures and dimensions of one beat: Effects of aortic valve stenosis and replacement

1990

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Within a thick heart-chamber wall, there is a midwall element or layer whose displacements best express systolic performance. The volume enclosed by that midwall element (Vm) and the average stress in that element (sigma m) can be calculated accurately by simple formulae. From simultaneous left-side pressure tracings and contrast cine-ventriculograms, Vm and sigma m were calculated at 20-ms intervals for an entire cardiac cycle in five normal subjects and in eight patients before and one year after replacement of stenotic aortic valves. Prior to surgery, the overloaded left ventricles were not hypertrophied enough to restore normal mid- and end-ejection stresses. Four had subnormal cavity ejection fractions, but all had subnormal midwall ejection fractions. All had subnormal fractional midwall ejection rates and prolonged active intervals (from the beginning of activation to the end of deactivation). Judging from pre-ejection pressure-development rates, the pressure-developing ability was not consistently elevated by concentric hypertrophy, because the stress-developing ability (contractility) was usually subnormal. The ability to shorten in the absence of afterload appeared to be subnormal in about half of the cases. The subnormal midwall ejection fractions appeared to be due to various combinations of increased mid- and late-ejection stresses, reduced contractility, and reduced shortening ability. On average and in several cases, reduced shortening ability appeared to be the main cause of the reduced performance. The effect of the slowed fractional midwall ejection rate to reduce the midwall ejection fraction was partially compensated by a prolonged active interval, by prolonged ejection time relative to the active interval, and by a more sustained ejection rate. Valve replacement partially restored all values except contractility towards normal, but the restorations of wall/cavity ratio and active interval were slight.

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Left ventricular mechanics in dilated cardiomyopathy

Cited by 62 publications

References 26 publications

Left-ventricular cavity dimensions in children with normal and dilated hearts

Left-ventricular cavity dimensions in children with normal and dilated hearts

Contribution of Exercise-Induced Mitral Regurgitation to Exercise Stroke Volume and Exercise Capacity in Patients With Left Ventricular Systolic Dysfunction

Estimation of left-ventricular systolic performance and its determinants in man from pressures and dimensions of one beat: Effects of aortic valve stenosis and replacement

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