A theoretical model for the dependency of heart rate on gradual vagal blockade by atropine

A mathematical model for the dependence of heart rate (HR) on atropine (AT) dose was devised, based on the IPFM (integral pulse frequency modulation) process as well as on other physiological and pharmacological assumptions. The model leads to two equations, which predict, as a function of AT dose, exact values for mean HR and for the power of HR fluctuations at respiratory frequency (HF_P). ECG data from an experimental procedure was used to test the validity of our model. A remarkable agreement between theory and experiment was observed Moreover, the computed values of the pharmacodynamic parameters, which were defined by the model, displayed a surprisingly small variance among the different subjects. These findings suggest that these parameters might be a basis for a quantitative classification method for cardiovascular control, expressing specific heart or brain diseases