Filling Volume Research Articles

Time to dP/dtmax, a preload-independent index of contractility: open-chest dog study.

A mathematical model of left ventricular pressure (LVP) during isovolumic contraction in the time domain shows the following predictions: 1) td, the time from onset of contraction to dP/dtmax and (dP/dt)/P, reflect only the time-dependent aspects of contraction, and are independent of preload; 2) dP/dtmax depends on both preload and the time-dependent aspects of contraction. To test preload independence we reduced filling volume (FV) by the method of ventricular volume clamps with a remote-controlled mitral valve in 7 anesthetized open-chest dogs. A decrease in FV of 80 +/- 15% produced a 29 +/- 12% (p < 0.001) decrease in LVP, 34 +/- 13% (p < 0.001) decrease in dP/dtmax, 13 +/- 4% (p < 0.001) decrease in t-dP/dtneg, and no change in td (-3 +/- 5%, NS). The heart rate (HR) dependence on td was assessed in other 5 anesthetized open-chest dogs. HR was changed with atrial pacing (50-240 bpm). td was linearly and inversely related to HR in each dog, and at each HR: dobutamine lowered and propranolol elevated this relation when compared to control (p < .001, both). Since dP/dtmax occurs usually before the opening of the aortic valve, td is, thus, also afterload-independent. Conclusion. This study supports the theoretical predictions that td is independent of preload and that it can serve, at any given HR, as a reliable index of contractility, provided that dP/dtmax occurs before the opening of the aortic valve.

Theoretical Analysis of the Hemodynamic Variables During Sustained Mechanical Alternans: Effect of Variations in Ventricular Filling Volume

A comprehensive discrete analysis of the hemodynamic variables during sustained mechanical alternans (SMA) shows that these variables are governed by simple mathematical relations. The analysis shows that the value of the slope created by the two alternating beats on the stroke volume-end diastolic ( SV-EDV) plane is γ̄ = (μ-1).(1+β)/(μ-β), where μ = SV s / SV w , SV s and SV w , denote the strong and weak beats, respectively, in the presence of one contractile state of the beating heart, and the beats associated with the higher and lower contractile states, respectively, in the presence of two alternating contractile states; β = FV s / FV w , FV s and FV w are the filling volumes following SV s and SV w , respectively. Two separate analyses show that this equation is valid, whether SMA is exhibited in the presence of one or two contractile states, and irrespective of the SV-EDV functional relationship. A criterion based on this slope, in terms of measurable parameters, is described to determine if SMA is caused by variations in EDV and FV. This comprehensive quantitative analysis enables a complete classification of the various types of SMA into subcategories with well-defined features. In particular, this analysis confirms former interesting theoretical consequence that when FV is constant, γ̄ attains the value of 2, independently of the value of μ or any other factor.

Noninvasive Evaluation of Left Ventricular Diastolic Function in Patients with Ischemic Heart Disease -Reconstruction of Transmitral Flow Rate and Filling Volume Curve with M-Mode, 2-Dimensional and Doppler Echocardiography-

Noninvasive Evaluation of Left Ventricular Diastolic Function in Patients with Ischemic Heart Disease -Reconstruction of Transmitral Flow Rate and Filling Volume Curve with M-Mode, 2-Dimensional and Doppler Echocardiography-