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Logistic Time Constant of Isovolumic Relaxation Pressure–Time Curve in the Canine Left Ventricle
Circulation, 1995Background The time constant of left ventricular (LV) relaxation derived from a monoexponential model has been widely used as an index of LV relaxation rate or lusitropism, although this model has several well-recognized problems. In the present study, we proposed a logistic model and derived a “logistic” time constant (
H, Matsubara +4 more
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European Heart Journal, 1980
We initially found that the fall in left ventricular pressure during isovolumic relaxation is exponential and therefore characterized by a time constant (T). To the extent that isovolumic pressure fall reflects myocardial events during relaxation, T indexes the time course of relaxation of the left ventricle.
M L, Weisfeldt +3 more
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We initially found that the fall in left ventricular pressure during isovolumic relaxation is exponential and therefore characterized by a time constant (T). To the extent that isovolumic pressure fall reflects myocardial events during relaxation, T indexes the time course of relaxation of the left ventricle.
M L, Weisfeldt +3 more
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Clinical and Experimental Pharmacology and Physiology, 1992
SUMMARY1. Subpressor calcium infusion for 1 h, which raised calcium levels to the upper limit of normal in normal subjects, increased plasma and urinary levels of atrial natriuretic peptide (ANP).2. Heart rate fell, presumably due to carotid baroreflex stimulation (supported by the fall in noradrenaline) and the resultant fall in cardiac output ...
Finn, WL +4 more
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SUMMARY1. Subpressor calcium infusion for 1 h, which raised calcium levels to the upper limit of normal in normal subjects, increased plasma and urinary levels of atrial natriuretic peptide (ANP).2. Heart rate fell, presumably due to carotid baroreflex stimulation (supported by the fall in noradrenaline) and the resultant fall in cardiac output ...
Finn, WL +4 more
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American Journal of Noninvasive Cardiology, 1992 Evaluation of Time Course of Left Ventricular Isovolumic Relaxation in Humans
1987Weiss and coworkers [1] first determined, in an open-chest, right-heart-bypass animal model, that left-ventricular-pressure decay during isovolumic relaxation can be approximated by a monoexponential function. Their technique required that the derived or best-fit monoexponential curve for the pressure data decay asymptotically toward zero pressure. [1,
William E. Craig +2 more
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Right ventricular myocardial isovolumic relaxation time and pulmonary pressure.
Clinical physiology and functional imaging, 2006Non-invasive assessment of pulmonary artery systolic pressure (PASP) has several limitations. As previously described by Burstin, the right ventricular (RV) isovolumic relaxation time (IVRt) is sensitive to changes in PASP. We therefore compared RV myocardial IVRt, derived by Doppler tissue imaging (DTI), with simultaneously measured invasive PASP ...
Per, Lindqvist +3 more
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Isovolumic relaxation time corrected for heart rate has a constant value from infancy to adolescence
Journal of the American Society of Echocardiography, 2003Isovolumic relaxation time (IVRT) is a valuable adjunct to Doppler flow signals measured at mitral valve level for proper interpretation of left-ventricular diastolic performance. Few data exist on reference values in the pediatric age group. Moreover, routine evaluation of IVRT in patients with limited cooperation ability is impeded by the common ...
Lothar, Schmitz +2 more
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American Heart Journal, 1992
The isovolumic relaxation time (IVRT) is an important noninvasive index of left ventricular diastolic function. Despite its widespread use, however, the IVRT has not been related analytically to invasive parameters of ventricular function. Establishing such a relationship would make the IVRT more useful by itself and perhaps allow it to be combined ...
J D, Thomas +6 more
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The isovolumic relaxation time (IVRT) is an important noninvasive index of left ventricular diastolic function. Despite its widespread use, however, the IVRT has not been related analytically to invasive parameters of ventricular function. Establishing such a relationship would make the IVRT more useful by itself and perhaps allow it to be combined ...
J D, Thomas +6 more
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The American Journal of Cardiology, 1980
Hypertrophic obstructive and nonobstructive cardiomyopathy are often associated with an abnormal prolonged left ventricular isovolumic relaxation time and a disturbed left ventricular filling pattern [1–5]. Recent experimental studies revealed that calcium antagonists may improve impaired left ventricular relaxation caused by ischemia or hypoxia [6, 7].
P, Hanrath +4 more
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Hypertrophic obstructive and nonobstructive cardiomyopathy are often associated with an abnormal prolonged left ventricular isovolumic relaxation time and a disturbed left ventricular filling pattern [1–5]. Recent experimental studies revealed that calcium antagonists may improve impaired left ventricular relaxation caused by ischemia or hypoxia [6, 7].
P, Hanrath +4 more
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