ELECTRICAL ANALOGY OF DIASTOLIC PRESSURE DIFFERENCE BETWEEN LEFT ATRIUM AND VENTRICLE

We proposed a mathematical model to describe the early filling process of the left ventricle and applied the model to in vivo experiments. T he solution of a second-order differential equation indicated that the pressure difference between the left atrium and ventricle during vent ricular filling (PD) could be explained by a transient response, i.e. decremental oscillation, in an LCR circuit. Thereafter, we analysed th e sequence of PD during vagal stimulation with two catheter-tip manome ters in 12 anaesthetised dogs and evaluated changes in the parameters of the system under various haemodynamic conditions. The values of ome ga(n) and xi were quite stable among beats within an episode of vagal stimulation, between episodes and even among dogs, despite the changes in haemodynamic variables. Pericardiotomy and partial discommunicatio n of the mitral valve with the left ventricular free wall by cutting t he mitral chordal tendons decreased omega(n) and increased xi, mainly because of the increase in C-LV. Occlusion of the coronary vascular be ds with large numbers of microspheres increased omega(n) and decreased xi, mainly because of the decrease in C-LV. Mitral obstruction with a n inflated balloon (increase in R) abolished the oscillatory changes a nd produced an exponential decay sequence of PD. In conclusion, both t he logical and experimental approaches indicated that the sequence of PD could be considered as decremental oscillation in the LCR circuit a nd the parameters omega(n) and xi could be good indices of the diastol ic property of the left ventricle.