Critical Evaluation of Indices of Myocardial Contractility Derived from the Isovolumic Phase of Contraction

Cw, Urschel; Ps, Vokonas; Ah, Henderson; Aj, Liedtke; Ld, Horwitz; Eh, Sonnenblick

doi:10.1159/000170791

Cited by 18 publications

(11 citation statements)

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“…1975, Marble et al 1981a). The extrapolations were carried out by unweighted least-squares solutions (Edwards 1976, Urschel et al 1980) by the linear and the semi-logarithmic methods (Kettunen et al 1984). The coefficients of correlation for the estimation of the exactness of fit were calculated according to Pearson (Edwards 1976) at the linear phase of computation.…”

Section: E T H O D Smentioning

confidence: 99%

“…Since a wide scattering of the values of the VCE at the very onset of isovolumetric systole is inevitable, especially if an erratic developed pressure is used for the calculation (Stein et al 1975), a 'true' end-diastolic time (Metzger et al 1970, Urschel et al 1980) and pressure were sought in the present series by means of an algorithm specially developed to eliminate the S.C. atrial boosting ('atrial kick') .…”

Section: Haemodynamicsmentioning

confidence: 99%

“…The application of the forcevelocity relation, derived originally from experiments with skeletal or cardiac papillary muscle preparations, to an intact heart ventricle necessarily evokes numerous steps of inherent modelling, simplifying, and approximation (Brutsaert & Paulus 1977, Urschel et al 1980). On the other hand, the interventions used here, when applied to the intact organism, cannot be 'pure effectors' for the selected haemodynamic variables.…”

Section: Haemodynamicsmentioning

confidence: 99%

“…1980). From these the maximum velocity of unloaded muscle fibre or contractile element, V, , , is one of the most widely studied parameters (Mason et al 1970, Parmley et al 1972, Grossman et al 1972, Urschel et al 1980). Correspondence Even if its specificity as an index of contractility is questioned both on a theoretical and experimental basis (Pollack 1970, Brady 1979, Mashima 1984, only few, if any, other indices of contractility based on the fundamental principles of muscle contraction are currently available for intact heart examinations.…”

mentioning

confidence: 99%

“…The linear method of extrapolation is simple (Mason et al 1970, Stein et a/. 1975, Marble et al 1981 and easy for computation, but many investigators prefer more complicated, non-linear procedures, in most cases, an exponential one (Nejad et al 1971, Peterson et al 1974, Weiss & Forster 1975, Goodyer & Wong 1977, Urschel et al 1980. T h e computer implications currently reported need some kind of manual editing (Urschel et a/.…”

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confidence: 99%

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The automatic computation of pressure‐derived maximal shortening velocity (V_max) of the unloaded contractile element in the intact canine heart left ventricle

Kettunen

Timisjärvi

Kouvalainen

et al. 1986

Acta Physiologica Scandinavica

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Estimation of the maximum velocity (Vmax) of the contractile element of the intact left ventricular wall muscle demands extrapolation of the force-velocity curve to zero load. The present paper describes our on-line computation system for measuring and analysing pressure derived Vmax using both linear (Vmax-lin) and exponential (Vmax-exp) extrapolation methods. The developed pressure during isovolumetric phase of systole was used as an equivalent of the force. Testing on anaesthetized artificially ventilated dogs showed the exponential function to fit pressure-velocity data better than the straight line did. The Vmax-exp attained 15-35% greater values than Vmax-lin, but both responded almost equally when considered on the basis of linear regression analysis (r = 0.991, n = 725). Changes of contractility caused by i.v. infusion of isoproterenol, calcium chloride or propranolol were practically similar when assessed by either method of Vmax computation, or by dP/dtmax. Volume loading by dextran infusion increased not only dP/dtmax, by 33 +/- 13%, but also Vmax, up to 24 +/-. When arterial pressure was raised by phenylephrine infusion, or heart rate by atrial pacing, dP/dtmax increased significantly while Vmax remained unaltered. Hence, the linear and exponential dP/dtmax increased significantly while Vmax remained unaltered. Hence, the linear and exponential extrapolation procedures provided comparable values for Vmax, but the linear one due to its simplicity is more suited for on-line computation. The Vmax thus obtained is, however, not independent of the changes in preload.

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Section: E T H O D Smentioning

confidence: 99%

Section: Haemodynamicsmentioning

confidence: 99%

Section: Haemodynamicsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The automatic computation of pressure‐derived maximal shortening velocity (V_max) of the unloaded contractile element in the intact canine heart left ventricle

Kettunen

Timisjärvi

Kouvalainen

et al. 1986

Acta Physiologica Scandinavica

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The thermodilution technique in on‐line computation of the left ventricular volumes on anaesthetized dogs

Kettunen

1985

Cathet. Cardiovasc. Diagn.

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The thermal dilution technique and its suitability for automatic computation of left ventricular volumes were evaluated on 28 anaesthetized dogs. The end-diastolic volume (EDV) was computed from ventricular washout curves in two ways, first utilizing the ratio between the indicator amount and its peak concentration (first ejection method); and secondly the ratio between stroke volume and ejection fraction with the latter obtained by subtracting the residual fraction from 1.0. The residual fraction was determined as the mean of ratios between successive steps of four ventricular ejections on the downslope of the curve (downslope method). The linear correlation coefficient between the EDV determinations (n = 366) was 0.926, and slope y = 1.14 X + 0.5 ml with 4.6 ml as standard error of estimate. The first ejection method gave on average 15% higher EDV values than the downslope method. When heart rate was increased by pacing from 88 to 240/min, both methods showed a reduction of the EDV, but the downslope method to a greater degree. When afterload was increased but heart rate decreased by phenylephrine, the first ejection method but not the downslope method indicated an increase in EDV. Otherwise, when pronounced tachy- or bradycardia were avoided, ventricular volumes yielded by the two methods were comparable. Indicator injection did not substantially affect ventricular pressure dynamics. The first ejection method seems to be a simple means for repeated measurements of EDV even in the case of diseased hearts.

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Time to dp/dt_max, a useful index for evaluation of contractility in the catheterization laboratory

Adler

Monrad

Sonnenblick

et al. 1996

Clinical Cardiology

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Hypothesis: The time from onset of contraction to dP/dtmax, td, is suggested as an index of contractility in the catheterization laboratory. Methods: We studied 22 normal patients and 18 patients with myocardial failure in the catheterization laboratory. The two groups were completely separated on the td‐heart rate (HR) plane. In the normal patients, HR = 73 ± 19 beats/min, td= 73 ± 11 ms, and an inverse linear relation td = 109‐0.49 × HR (p<0.001) exist. In the patients with myocardial failure, despite significantly higher HR than in normal patients (HR = 93 ± 14 beats/min) (p <0.001), td paradoxically increased (td = 89 ±11 ms, p<0.0001). Conclusions: These findings support a mathematical analysis of the left ventricular pressure (LVP) during isovolumic contraction in the time domain which shows that td and (dP/dt)/P reflect the time‐dependent aspects of contraction and, hence, decrease with increasing contractility. This study shows that td, at any given HR, is a reliable index of contractility. Thus, a ready‐to‐use td‐HR plot containing a well‐based separation line can provide a reliable and simple method for determining contractility in the catheterization laboratory by examining whether a patient's td value at any HR is below (normal) or above (impaired contractility) the separation line.

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Critical Evaluation of Indices of Myocardial Contractility Derived from the Isovolumic Phase of Contraction

Cited by 18 publications

References 20 publications

The automatic computation of pressure‐derived maximal shortening velocity (V_max) of the unloaded contractile element in the intact canine heart left ventricle

The automatic computation of pressure‐derived maximal shortening velocity (V_max) of the unloaded contractile element in the intact canine heart left ventricle

The thermodilution technique in on‐line computation of the left ventricular volumes on anaesthetized dogs

Time to dp/dt_max, a useful index for evaluation of contractility in the catheterization laboratory

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Critical Evaluation of Indices of Myocardial Contractility Derived from the Isovolumic Phase of Contraction

Cited by 18 publications

References 20 publications

The automatic computation of pressure‐derived maximal shortening velocity (Vmax) of the unloaded contractile element in the intact canine heart left ventricle

The automatic computation of pressure‐derived maximal shortening velocity (Vmax) of the unloaded contractile element in the intact canine heart left ventricle

The thermodilution technique in on‐line computation of the left ventricular volumes on anaesthetized dogs

Time to dp/dtmax, a useful index for evaluation of contractility in the catheterization laboratory

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The automatic computation of pressure‐derived maximal shortening velocity (V_max) of the unloaded contractile element in the intact canine heart left ventricle

The automatic computation of pressure‐derived maximal shortening velocity (V_max) of the unloaded contractile element in the intact canine heart left ventricle

Time to dp/dt_max, a useful index for evaluation of contractility in the catheterization laboratory