The blood can be considered as a real fluid flowing in fixed vibrating myocarde canal. Its ejection during the left ventricular contraction is the phenomenon hereby studied. The left ventricle has been taken as a checking volume encompassing one part of aorta. The limit of this thermodynamic system is dotted and situated under endocarde. The blood in this closed ventricle is considered in stationary state. A vent connects the left ventricle to the aorta and the system receives the work power from nodal tissue. The study aims to dial differential enthalpy and to show that it can be used to quantify the cardiac power. The study has been performed on healthy persons, men and women, of Democratic Republic of Congo. The sample of 20.000 cases of healthy persons whose age varies between 13-73 years has been investigated. The blood pressure measurements and calculations are our methodology of work. The figures have been plotted by means of origin 8 program. In each cross section of life the parameter in title has been calculated and correlated to different ages. Also the cardiac power has been calculated at different cardiac frequencies. Interpretations of the results are commented. A new concept of differential enthalpy is introduced in this paper to show that this cute parameter has twofold roll. Firstly it can be used to calculate cardiac power and secondly it can help to evaluate the work power from Keith Flack node. This last assertion constitutes the content of our research on Keith Flack impetus assessment in heart acting.
