IngentaConnect Operative contractility: A functional concept of the inotropic st...

Authors: Curiel, Roberto¹; Perez-Gonzalez, Juan²; Torres, Edwar³; Landaeta, Ruben³; Cerrolaza, Miguel³

Source: Clinical and Experimental Pharmacology and Physiology, Volume 32, Number 10, October 2005 , pp. 871-881(11)

Abstract:

SUMMARY

1. Initial unsuccessful attempts to evaluate ventricular function in terms of the ‘heart as a pump’ led to focusing on the ‘heart as a muscle’ and to the concept of myocardial contractility. However, no clinically ideal index exists to assess the contractile state. The aim of the present study was to develop a mathematical model to assess cardiac contractility.

2. A tri-axial system was conceived for preload (PL), afterload (AL) and contractility, where stroke volume (SV) was represented as the volume of the tetrahedron. Based on this model, ‘operative’ contractility (‘OperCon’) was calculated from the readily measured values of PL, AL and SV. The model was tested retrospectively under a variety of different experimental and clinical conditions, in 71 studies in humans and 29 studies in dogs. A prospective echocardiographic study was performed in 143 consecutive subjects to evaluate the ability of the model to assess contractility when SV and PL were measured volumetrically (mL) or dimensionally (cm).

3. With inotropic interventions, OperCon changes were comparable to those of ejection fraction (EF), velocity of shortening (Vcf) and dP/dt-max. Only with positive inotropic interventions did elastance (Ees) show significantly larger changes. With load manipulations, OperCon showed significantly smaller changes than EF and Ees and comparable changes to Vcf and dP/dt-max. Values of OperCon were similar when AL was represented by systolic blood pressure or wall stress and when volumetric or dimensional values were used.

4. Operative contractility is a reliable, simple and versatile method to assess cardiac contractility.

Keywords: computer modelling; contractile function; haemodynamic; heart failure; ventricular function

Document Type: Original article

DOI: 10.1111/j.1440-1681.2010.04282.x

Affiliations: 1: Centro Medico Docente La Trinidad, 2: Instituto de Medicina Experimental, Facultad de Medicina and 3: Centro de Bioingeniería, Facultad de Ingeniería, Universidad Central de Venezuela, Caracas, Venezuela

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Operative contractility: A functional concept of the inotropic state