Revealing the heart’s innermost secrets – through the microscope

Cardiac health can be studied from several perspectives – from the clinical patient trial to the tiny protons inside the cells. Here in CERG we include the whole spectre to better understand the heart and its physiology, and the group members come from many different branches of the science tree. Our newest employees are post docs. Allen Kelly and Nathan Scrimgeour, both electrophysiologists from the University of Glasgow and the University of Adelaide, respectively. I have challenged them to describe their research fields, that might be a little bit complicated for us mere mortals to comprehend. However, basic research represents one of the cornerstones in CERG’s research and provides important knowledge on how the heart works and how exercise affects heart function.

IMG_5715One common way of explaining the cardiovascular system is to compare it to a plumbing system in a house, where water pumped to all the rooms is like blood being pumped to all of the organs. In this analogy, pipes represent blood vessels as the paths through which the fluid circulates, and a pump represents the heart, providing the force that drives the fluid through those paths. However, just as a house also requires an electrical system for everything, including the pump, to work, our bodies need an electrical system for everything, including the heart, to work.

The tightly orchestrated movement of ions (electrically charged atoms) in and out of cardiac (heart) muscle cells is what effectively flips the “on” switch, transmitting this signal and triggering a wave of contraction through the heart, and consequently pumping blood around the body. There are specialised molecules that allow ions in, others that allow ions out, and some that work to return everything back to the way it started to flip the switch back to “off”, ready for the next heartbeat. But what happens if one or more parts of this ionic movement “orchestra” are out of time or out of tune with the rest?

Our research background involves the study of different kinds of heart failure. A major cause of heart failure is myocardial infarction, or heart attack; blockage of a blood vessel in the heart leading to damage of the heart muscle and the formation of scar tissue.  One of the most important areas of research in heart disease focuses on understanding the processes occurring inside the heart muscle that cause this damage, so that we might find ways to minimize it. Just 10 years ago, being able to visualise these processes as they happen immediately after a heart attack would have been the stuff of dreams. However, in December last year, Li and colleagues (2012), using a special type of imaging technique known as two-photon microscopy, were able to see the immune system response to a myocardial infarction in a beating heart, tracking the movement of immune cells that are just two hundredths of a mm across (about 10 times smaller than the width of a human hair).  It is advances such as this which drive the rapid pace of heart research today.

IMG_5711Here at CERG, a similar newly-installed two-photon imaging system is helping researchers understand and enhance the benefits of exercise as a treatment strategy in heart disease.  Using this technology, we will be studying how heart disease alters the electrical activity of the heart and normal control of the heartbeat. In heart disease, changes within the heart muscle may disrupt the normal heart beat, leading to uncoordinated beats, or arrhythmias. Arrhythmias are becoming increasingly common and are associated with conditions such as heart disease or high blood pressure. The uncoordinated heart contractions of an arrhythmia mean that blood is inefficiently pumped, leading  to anything from dizziness, uncomfortable palpitations, increased risk of stroke, or sudden cardiac death – one of the most common causes of death in western societies. By visualising changes in the heart muscle that cause these arrhythmias, and how these changes are affected by exercise, we can develop new and improved therapies to prevent these potentially fatal arrhythmias from occurring.

One of the problems with trying to understand specifically why arrhythmias occur and what can be done to prevent or treat them, is understanding which part of the “orchestra” isn’t working properly to start with. As electrophysiologists, we are able to record the electrical activity of cardiac muscle cells, and attempt to understand how each part of this “orchestra” responds to different conditions – for example following heart failure, after an exercise programme, or in response to therapeutic drugs – to lead to better outcomes for patients.

Having just arrived at NTNU, we are joining a team of research scientists who continually contribute to the accelerated pace of current research with many publications on the benefits of exercise to society not just as a lifestyle enhancement, but as an effective treatment for heart disease. Yes, the pace of research may seem overwhelming at first, but it is an exciting time to be a cardiac physiologist.

Allen Kelly and Nathan Scrimgeour, post docs at CERG.

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