Telecardiology: results and perspectives of an operative experience.

A telecardiology system has been established between six Italian hospitals. Four of them are connected using three ISDN lines; the remaining two are connected with only a single ISDN line. The telecardiology system was evaluated between two hospitals.

Identification and physiological relevance of an exponentially tapered tube model of canine descending aortic circulation.

The aim of this study was to evaluate the effect of incorporating aortic tapering in a tube model of descending aortic circulation. We described the descending aorta and its peripheral load by an exponentially tapered transmission tube terminating in a first-order, low-pass filter load. Under the assumption of adaptation between the transmission tube and the terminal load, the input impedance of this model was characterized by five free parameters, the characteristic impedance, Zce(0), at the tube entrance; the product, qde, between the tapering factor q and the tube length, de, the product ce(0)de, between the compliance, ce(0), at the tube entrance and the tube length; the time constant, tau ne, of the load and the peripheral resistance, Rp.

Comparison of linear and nonlinear formulations of the three-element windkessel model.

The three-element windkessel model incorporating a constant compliance (model A) was compared with two nonlinear versions of the same model (models B1 and B2) incorporating a pressure-dependent compliance. The aim was to test whether nonlinear elasticity yielded better model behavior in describing ascending aortic pressure-flow relationships and interpreting the physical properties of the arterial system. Exponential and bell-shaped compliance vs.

Fit to diastolic arterial pressure by third-order lumped model yields unreliable estimates of arterial compliance.

The pressure pulse contour analysis method uses a third-order lumped model to evaluate the elastic properties of the arterial system and their modifications with adaptive responses or disease. A fundamental assumption underlying this method is that the estimates of model parameters (two compliances, an inertance, and a peripheral resistance) obtained from a measurement of cardiac output, and a simultaneous measurement of an arterial pressure, are independent of the pressure measurement site. If true, this hypothesis would provide a minimally invasive method for estimation of arterial compliance.