Another marvel of medical science is the replacement of heart valves with artificial ones.

Thanks to the determination of cardiac surgeons such operations are now considered relatively routine. However complications can arise during rehabilitation.

For instance the valves may fail or infections may develop. Assessing the post-operative risk for individual patients is a complex problem.

As you read this a team comprising cardiologists from the Cardiac Surgery Department at the Prince Charles Hospital and Associate Professor Geoff McLachlan from the Mathematics Department at the University of Queensland are investigating the problem mathematically. A study is being conducted using 2000 people who have undergone cardiac surgery.

Because of the complexity of the problem Associate Professor McLachlan has developed a sophisticated statistical method known as mixture modelling to analyse the data. The model gives an accurate picture of the recovery rates as it allows for the vastly different survival characteristics of individual patients. Ultimately the results of the study will suggest the level and type of post-operative care a patient requires.

Mathematics is also used in many other areas of medicine. For instance, Professors L. Bass and A. Bracken, of the Mathematics Department and Professor S. Pond of the Department of Medicine are collaborating in research about the liver.