Bricks, Bones and the Heart

At the University of Calgary, Dr. Nigel G. Shrive, P.Eng. is a professor in the Department of Civil Engineering and also Director of the McCaig Institute for Bone and Joint Health in the Faculty of Medicine. CCE spoke to him in January.

Q. What does the structural engineering of masonry have in common with the human body?

The basic engineering principles that apply to masonry are the same principles that you would apply to a ligament, to cartilage, to hard tissue. So structural engineering has huge applications in the medical field because your body is made up of structures. You could describe reinforced masonry as a fibre-reinforced viscoelastic composite. A ligament, or heart tissue, is also a fibre-reinforced viscoelastic composite.

Q. How did you get involved with both structural and biomedical engineering?

After I graduated in the U.K. in 1974 I couldn’t get a job so I came on a one-year contract to Calgary to teach structures and I’ve been here ever since. I was introduced to Dr. Cy Frank, who is an orthopedic surgeon, and we began working together in understanding how ligaments work, what their role is, how they perform their job, and how they heal. We’re especially interested in why grafted and transplanted ligaments are never as good as those that are undamaged.

Then about 17 years ago a doctor in the cardiology group, John Tyberg, wanted to understand what was going on with the septum, the tissue wall that separates the left and right ventricles of the heart. With patients who have certain diseases the septum starts going sideways, flattening and inverting, closing in the left ventricle while enlarging the right. This doctor wanted to understand the mechanics of what was going on.

I made a finite element model of the tissue and the doctor was amazed at what the model revealed. So we have done a whole series of studies on how the heart behaves structurally under normal and abnormal loading, both as it contracts and as it relaxes. We have examined how the various tissues interact. We found some really interesting outcomes that have made a difference to the way some cardiologists practice.

Q. IS IT ALL COMPUTER MODELLING, OR Do you actually work with flesh and blood sometimes?

Oh yes, occasionally we go to the butcher’s shop and get bones and joints. We were using New Zealand lambs at one point. They’re young and have not got arthritis so you can do useful tests on their tissues.

Q. What about your work in masonry?

I’ve always been interested in the conservation of older structures. For me, an old structure is a tangible piece of evidence of the skill of our ancestors. If you knock a structure down, all you have is a picture, whereas I think that we need to give our successors some evidence of where we have come from, to give them roots.

Q. What are the projects you have done recently?

I worked on the Parliament Buildings in Ottawa, and currently we’re doing some work on the Prince of Wales Fort in Churchill, Manitoba. It’s a national historic site and Parks Canada is trying to find out why the walls have been bulging and collapsing.

If I leave Canada with a number of historic buildings that are still standing through the work that I have contributed to, buildings that otherwise would have fallen down or been demolished, that would be something I would feel comfortable about.

Q. Where does your heart lie? With the medical or the masonry work?

With both. I have often thought that I should give up one, but I cannot ever work out which because they’re both too close to home.