Modelling > Blood circulation parameters > Heart characteristics > Left ventricular inotropic status

This parameter in our model is the major indirect characteristic of myocardium functional condition. It is included in mathematical description of left ventricular inotropic factor k_L:

(57)

The formula (57) is the variant of the formula (54). The parameter characterizes base (independent from nervous and hormonal influences) constituent of left ventricular inotropic factor.

Chart

Dependence of inotropic factor from inotropic status under different values of neurohumoral factor

Myocardium inotropic status (contractility) is characterized by ventricular ability to throw more blood volume in vessels without increase of enddiastolic volume (i.e. without use of Frank-Starling's law), or the ability to throw the equal volume under more pressure in great vessels. It means, that under the same values of enddiastolic volume ventricles can extend their power. Under decrease of inotropic function (decrease of contractility) myocardial tension (increase of enddiastolic volume) does not cause the increase of myocardial power.

The parameter is used for modelling of functional circulation modes, connected with reduction of heart pump function (myocardial infarction, heart failure of different pathogenesis, hypoxemia, acidosis, hypercapnia, myocarditis and etc.). According to the works of N.M.Amosov and co-authors [4], [6] the ordinary value of inotropic status is 0.55 - 0.6. Conditions with the reduction of pump function of left ventricle are characterized by the decrease of this value to 0.3 (cardiogenic shock).

The parameter is used for modelling of drug action of preparations with positive inotropic action (noradrenaline and its derivatives, cardiac glycosides and others). Action of such preparation is described with the increase of parameter value in comparison with its normal one. Drug action of preparations with negative inotropic action (β-blockers, procainamide hydrochloride, quinidine, barbiturates and others) is described with the decrease of parameter value in comparison with its normal one.

Modelling > Blood circulation parameters > Heart characteristics > Left ventricular inotropic status