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Circulation publishes original contributions of scientific excellence concerned with clinical and laboratory research relevant to cardiovascular disease. The research articles are from many disciplines including cardiovascular medicine and surgery, epidemiology, radiology, and pathology, to appeal to cardiologists, internists, cardiovascular surgeons, nurses, and others interested in cardiovascular medicine. Coverage includes Cardiovascular News, Clinical Cardiology, From Bench to Bedside, Images in Cardiovascular Medicine, and the AHA Calendar.
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Institución detectada Período Navegá Descargá Solicitá
No detectada desde jul. 2007 / hasta jun. 2018 Ovid


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Estados Unidos

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Determination of Left Ventricular Chamber Stiffness From the Time for Deceleration of Early Left Ventricular Filling

William C. Little; Michiya Ohno; Dalane W. Kitzman; James D. Thomas; Che-Ping Cheng

<jats:p> <jats:italic>Background</jats:italic> A noninvasive measure of left ventricular (LV) chamber stiffness (K <jats:sub>LV</jats:sub> ) would be clinically useful. Our theoretical analysis predicts that K <jats:sub>LV</jats:sub> can be calculated from the time for deceleration of LV early filling (t <jats:sub>dec</jats:sub> ) by </jats:p> <jats:p> <jats:disp-formula> <jats:tex-math notation="LaTeX">\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[K_{LV}{=}\frac{{\rho}\ {\cdot}\ L}{A}\ {\cdot}\ (\frac{{\pi}}{2}\ {\cdot}\ \frac{1}{t_{dec}})^{2}\] \end{document}</jats:tex-math> </jats:disp-formula> </jats:p> <jats:p>where ρ=density of blood, L=effective mitral length, and A=mitral area.</jats:p> <jats:p> <jats:italic>Methods and Results</jats:italic> We tested this hypothesis in eight conscious dogs instrumented for measurement of LV pressure (P) with use of a micromanometer and volume (V) with use of sonomicrometers. K <jats:sub>LV</jats:sub> was determined as the slope of the late diastolic portion of the LV P-V loop. K <jats:sub>LV</jats:sub> was varied from 0.99±0.35 to 2.58±0.92 mm Hg/mL with use of three graded doses of phenylephrine. We assumed that ρ=1.0 and that L/A=3.4. Thus, we predicted that K <jats:sub>LV</jats:sub> =(0.08/t <jats:sub>dec</jats:sub> ) <jats:xref ref-type="bibr"> <jats:sup>2</jats:sup> </jats:xref> . The LV filling pattern was determined from the derivative of LV volume (dV/dt). t <jats:sub>dec</jats:sub> was measured from peak early filling to the end of early filling. Predicted K <jats:sub>LV</jats:sub> and actual K <jats:sub>LV</jats:sub> were closely correlated ( <jats:italic>r</jats:italic> =.94, SEE=0.06 mm Hg/mL, <jats:italic>P</jats:italic> &lt;.05). The regression line was close to the line of identity (slope=0.95, intercept=0.13 mm Hg/mL). Dobutamine did not alter the relation between t <jats:sub>dec</jats:sub> and K <jats:sub>LV</jats:sub> . t <jats:sub>dec</jats:sub> determined from the mitral valve flow velocity measured with Doppler echocardiography correlated well with that measured by dV/dt ( <jats:italic>r</jats:italic> =.89, <jats:italic>P</jats:italic> &lt;.01) but was 0.02 seconds longer. K <jats:sub>LV</jats:sub> -calculated t <jats:sub>dec</jats:sub> from the corrected Doppler t <jats:sub>dec</jats:sub> provided a good estimate of measured K <jats:sub>LV</jats:sub> ( <jats:italic>r</jats:italic> =.75, SEE=0.5 mm Hg/mL, <jats:italic>P</jats:italic> &lt;.01). </jats:p> <jats:p> <jats:italic>Conclusions</jats:italic> LV chamber stiffness can be determined from the time for deceleration of LV early filling, which can be measured noninvasively. </jats:p>

Palabras clave: Physiology (medical); Cardiology and Cardiovascular Medicine.

Pp. 1933-1939