Irish scientists have become the first in the world to literally ‘pull on heart strings', a breakthrough that will help the scientific community to better understand the impact of ageing and disease on the heart.

The team from AMBER (the Advanced Materials and BioEngineering Research Centre), which is based at Trinity College Dublin, has succeeded in measuring the fatigue strength of chordae tendineae, which are cord-like tendons in the heart.

Fatigue strength refers to how long something can endure repeated stress before it fails to work properly.

Chordae tendineae are found in the mitral valve, which lies between the left atrium and left ventricle - the chambers of the heart. They are necessary for normal blood flow.

The scientists were successful in measuring the length of time these tendineae can endure repeated stress before rupturing. This rupturing is one of the main causes of a number of heart conditions, including severe mitral regurgitation (MR), also known as ‘leaking valves'.

Severe MR can cause symptoms such as tiredness, dizziness, shortness of breath and chest pain. It can lead to high blood pressure and even heart failure. This research could lead to new ways of preventing severe MR in the future.

"Heart disease is one of the most prevalent conditions in Ireland, with approximately one in four people dying from heart attack or stroke each year. Our research investigates the amount of stress chordae tendinae can endure and for how long, prior to rupture, which can lead to a number of conditions.

"This is known, in engineering terms, as fatigue strength and is useful for measuring how quickly something that endures repeated stress will fail. These results are important because although there are predictor scales or models correlating stress levels with specific diseases, we have to date been missing the link relating those stress levels to the time before rupture occurs. With our study we have completed this missing link," explained AMBER investigator, Prof Bruce Murphy.

The next stage of the research will be to measure the fatigue strength of different types of chords to see which are more suitable for heart valve transplants in the future. Usually artificial valves or the valves of a pig are used in transplants.

"As part of this research we were testing the chordae tendinae of a pig's heart. Porcine (pig) mitral valves are often used for transplants, however, compared to transplanted mechanical valves, porcine valves degrade quickly. The next stage of our research will be to measure the fatigue strength of the chords in a range of treated porcine mitral valves that are used or being considered for use in transplants. This could potentially help determine the best options for mitral valve transplants," said AMBER PhD candidate, Gillian Gunning.

AMBER is funded by Science Foundation Ireland. Details of these findings are published in the journal, Acta Biomaterialia.