Modified asymmetric T-tube model to infer aortic wave reflection

A modified system of the T-tube was set up to represent the systemic arterial loading system as seen by the left ventricle (LV). This model has been obtained by placing in parallel two uniform tubes, each one loaded with a complex load. Individual tubes respectively represent upper (head, neck and upper limbs) and lower (trunk and lower limbs) portions of circulation. This model differs from the original T-tube model in that the transmission paths have no frictional losses and are terminated with complex impedances, rather than simple resistors. To estimate model parameters (load and tube compliances, tube inertances, characteristic impedances, and peripheral resistances), the authors measured ascending aortic pressure and flow in a group of six open-chest, anesthetized dogs. Parameter estimates were obtained by fitting experimental pressure to pressure predicted by the model from experimental flow. This model was able to provide suitable estimates of arterial parameters and to give a suitable description of both pressure-flow relations and reflection phenomena in the ascending aorta and in the upper and lower body circulation.<>