Is the Ejection Fraction an Index of Myocardial Contractility?

Krayenbühl, H. P.; Bussmann, W.‐D.; Turina, Marko; Lüthy, E.

doi:10.1159/000166167

Cited by 47 publications

(11 citation statements)

References 3 publications

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“…Our in vivo experimental study with an intact cardiovascular system confirms previous observations about the influence of the cardiac loading conditions on LVEF [23, 24, 34–36], but more importantly, it also provides the empirical demonstration about the real nature of LVEF. Since LVEF is primarily governed by the influence of Ees and Ea, it mainly reflects the balance between LV contractile function and the arterial system.…”

Section: Discussionsupporting

confidence: 86%

“…Ideally, an index of contractility index should be sensitive to changes in myocardial contractile state but indifferent to loading conditions [6]. Although LVEF has been traditionally used as a clinical measure of LV systolic performance, its dependence on preload and especially afterload changes have been well documented experimentally over five decades ago by Krayenbuhl et al [23], later corroborated in isolated canine ventricles by Kass et al [24] and theoretically described by Robotham [6]. However, the recognition that LVEF does not only depend solely upon myocardial contractility but also upon other determinants of the ventricular function has been increasingly recognized in critically ill patients with the growing use of echocardiography in ICU to assess LV function [3, 9, 25].…”

Section: Discussionmentioning

confidence: 99%

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Determinants of left ventricular ejection fraction and a novel method to improve its assessment of myocardial contractility

García¹,

Jian

Settels

et al. 2019

Ann. Intensive Care

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Background The aim of this study was to quantify the impact of different cardiovascular factors on left ventricular ejection fraction (LVEF) and test a novel LVEF calculation considering these factors. Results 10 pigs were studied. The experimental protocol consisted of sequentially changing afterload, preload and contractility. LV pressure–volume (PV) loops and peripheral arterial pressure were obtained before and after each intervention. LVEF was calculated as stroke volume (SV)/end-diastolic volume (EDV). We studied global cardiac function variables: LV end-systolic elastance (Ees), effective arterial elastance (Ea), end-diastolic volume and heart rate. Diastolic function was evaluated by means of the ventricular relaxation time ( τ ) and ventricular stiffness constant ( β ) obtained from the end-diastolic PV relationship. Ventriculo-arterial coupling (VAC), an index of cardiovascular performance, was calculated as Ea/Ees. LV mechanical efficiency (LVeff) was calculated as the ratio of stroke work to LV pressure–volume area. A linear mixed model was used to determine the impact of cardiac factors (Ees, Ea, EDV and heart rate), VAC and LVeff on LVEF during all experimental conditions. LVEF was mainly related to Ees and Ea. There was a strong relationship between LVEF and both VAC and LVeff ( r 2 = 0.69 and r 2 = 0.94, respectively). The relationship between LVEF and Ees was good ( r 2 = 0.43). Adjusting LVEF to afterload ( ) performed better for estimating Ees ( r 2 = 0.75) and improved the tracking of LV contractility changes, even when a peripheral Ea was used as surrogate (Ea = radial MAP/SV; r 2 = 0.73). Conclusions LVEF was mainly affected by contractility and afterload changes and was strongly related to VAC and LVeff. An adjustment to LVEF that considers the impact of afterload provided a better assessment of LV contractility.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Determinants of left ventricular ejection fraction and a novel method to improve its assessment of myocardial contractility

García¹,

Jian

Settels

et al. 2019

Ann. Intensive Care

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“…This is in aggreement with a recent publication presented by Brent et al [1,2]. Therefore we conclude -as was pointed out by Krayenbiihl for the left ventricle [12] that ejection fraction is not an 'index of myocardial contractility' considering the right ventricle.…”

Section: Right Ventricular Systolic Functionsupporting

confidence: 89%

Right ventricular function in patients with chronic obstructive pulmonary disease

et al. 1985

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Simultaneous right heart catheterization and radionuclide ventriculography were performed in 27 patients with a wide range of chronic obstructive pulmonary disease. Central hemodynamics and radionuclide studies were done at rest and during exercise. In the resting state the right ventricular ejection fraction (RVEF) was in the normal range (43.3 +/- 6%). During exercise a significant (p less than 0.001) decrease of RVEF to 38.8 +/- 6.7% occurred. The pulmonary artery mean pressures were 19.9 +/- 3.8 at rest. During exercise a significant (p less than 0.001) increase to 41 +/- 9.8 mm Hg occurred. There was a linear relationship between pulmonary pressures and RVEF during exercise in patients with pulmonary artery pressures not exceeding 35 mm Hg. In patients with right ventricular end-diastolic wall thickness greater than or equal to 6 mm a curvilinear relationship between these parameters could be observed with a flattening of the curve at higher pressures (greater than 35 mm Hg) and lower ejection fractions (less than 35% RVEF). Radionuclide ventriculography cannot substitute for right heart catheterization. Echocardiography is useful for interpretation of right ventricular ejection fractions in advanced chronic obstructive pulmonary disease.

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“…It is largely on account of the problems introduced by afterload changes that power and work measurements have not proved to be popular indices of cardiac performance, and attempts have been made to discover other indicators. Such indices range from hemodynamic and geometric descriptors, such as cardiac output (Braunwald, 1971), end-diastolic pressure (Braunwald and Ross, 1963), ventricular volume or mass (Dodge and Baxley, 1969), and ejection fraction (Krayenbuhl et al, 1968), to mechanical descriptors most of which have been justified as applying the principles of muscle mechanics to the intact heart. This latter group covers three phases: first, the pre-ejection phase which includes various forms containing the first time derivative of left ventricular pressure (dp/dt) (Mason et al, 1971), often with corrections for possible influences of preload or afterload changes (Mahler et al, 1975), and has been extended to include V max , the extrapolated velocity of shortening at zero load (Sonnenblick, 1962); second, the ejection phase, which is based on variables such as the velocity of circumferential fiber shortening (Benzing et al, 1974) or on more detailed representations involving tension-velocity-length relations (Peterson et al, 1973); and third, the diastolic phase, in which stiffness, compliance, and various elasticity moduli and constants may be defined (Mirsky, 1976;Brutsaert et al, 1980).…”

Section: The Effects Of Peripheral Impedance and Inotropic State On Tmentioning

confidence: 99%

The effects of peripheral impedance and inotropic state on the power output of the left ventricle in dogs.

Sdougos¹,

Schultz²,

Tan³

et al. 1982

Circulation Research

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SUMMARY The power output of the left ventricle as measured by the product of the Fourier components of aortic pressure and aortic flow is linked by definition to the arterial impedance facing the heart as measured by the quotient of these components. Consequently, the use of power measurements to assess ventricular performance can be ambiguous when accompanied by afterload changes. The heart is considered to function normally between two extremes, a constant flow pump, and a constant pressure pump, and two power limits are defined from these. The power limits describe the extent to which impedance changes can affect the power delivered by the left ventricle. Measured power changes that are found to lie outside the two limits can be unambiguously ascribed to changes in inotropic state. The results from preliminary dog experiments designed to test this method are reported. Cardiac sympathetic stimulation and isoprenaline infusion were used to provide a pure inotropic stimulus and a mixture of inotropic and afterload changes, respectively. The technique was able to detect inotropic changes in the heart even in the presence of simultaneous changes in afterload. Eight conventional indices of cardiac performance were monitored for comparison. The extent of their afterload dependence may not be as easily quantified. Circ Res 50: [74][75][76][77][78][79][80][81][82][83][84][85] 1982

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Is the Ejection Fraction an Index of Myocardial Contractility?

Cited by 47 publications

References 3 publications

Determinants of left ventricular ejection fraction and a novel method to improve its assessment of myocardial contractility

Determinants of left ventricular ejection fraction and a novel method to improve its assessment of myocardial contractility

Right ventricular function in patients with chronic obstructive pulmonary disease

The effects of peripheral impedance and inotropic state on the power output of the left ventricle in dogs.

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