The assessment of haemodynamic function of diseased and prosthetic heart valves in patients

The paper deals with reasons why current methods of assessing the resistance to flow offered by heart valves in patients are unsatisfactory. A theoretical and simulation study suggested that a measure of energy or power loss per unit flow was likely to be of more use and subsequent clinical investigations have confirmed this. The computation can be readily carried out in a hard-wired parallel hybrid module for operating theatre or catheter laboratory use.