Search for the Horizon: Where Do Coronary Waves Originate?

This project tries to answer an obvious question that's been largely overlooked by the research community -- when we measure pressure and velocity in a patient's vessel, where are those signals coming from? 

When a person experiences a heart attack, a majority of the time it is due to the blockage of one of the vessels supplying the heart muscle. While the treatments focus on re-establishing the flow (revascularisation), having more information on the hemodynamics helps doctors plot the future course of therapy. After all, the coronary circulation is a complex system that consists of hundreds of millions of both large and small vessels, and a single approach definitely does not fit all patients!

Thanks to previous research, there is a technique called Wave Intensity Analysis, which allows us to figure out what's happening deep down in the small vessels embedded within the myocardial walls, as opposed to events taking place in the upper circulation. However, because pulse waves have a tendency to reflect at vascular junctions, we don't get to see what's going on in most of the deeper circulation. The question is, how deep? The depth at which we can't observe at the top of the tree any originating waves is referred to as the Horizon.

Why do we care about this horizon? Many reasons - a parameter derived from these pulse waves has been shown to correlate with the recovery of the heart muscle following a heart attack, for example (see this article). Doctors are interested in using these indices to infer the health status of the affected myocardial regions and the integrity of the microcirculation. If the waves do not actually originate from the microcirculation (or are entirely trapped so as to be unobservable), this would be quite misleading!

It is difficult to find out directly where this horizon is, in a patient. Fortunately, (with much effort) we have acquired a very high-resolution geometry of the whole coronary network in animal models, which will serve as the starting point of this project. Specific work involved is described below.

 

"What will I be actually doing in this project?"

The idea is to simulate flows in the extracted networks to emulate the cathlab procedures. We have the freedom to prune away deeper vessel segments (shown below), so it's expected that the higher we prune, greater the change in the observed flow profile will be. Conversely, the lower we prune, at some stage, the changes in flow will become negligible, identifying the horizon. To do this you will learn how to run our in-house 1D flow simulation program, manipulate vascular networks in matlab, and a little bit of the theory behind pulse wave propagation. The rest of the time will be devoted to fun stuff.

"I am not confident at coding... am I going to be able to handle it?"

The work involved is mainly learning to use already-completed programs to answer a question, rather than to implement any new ones. We understand the time allocated in an undergraduate projects doesn't allow lengthy development work, and you will get plenty of help if you require it.

"How much supervision will be offered?"

There are two supervisors for this project, and one of us will always be available if you need help. In the project we did last year, we typically had two full days of work a week plus a web-based progress tracking system (so you can do the work where/when it suits you).

more questions?

By all means come in and talk to myself (Jack) or Simone, we're both on 3rd floor of Lambeth wing. Drop us an email to make sure we're in. Or, you can leave your question in the comments below.