Wellcome Image of the Month: Heart Strings
This fascinating new 3D image of the lower region of the heart is among the recent acquisitions of the Wellcome Images’ biomedical collection. While it stands on its own as an informative piece of datum, the fact that it depicts a swirling arrangement of cardiac fibres makes for its particularly apt title: ‘Heart Strings’.
The idiom ‘to tug at one’s heart strings’ originated from people’s early understanding of the anatomy of the heart, although it is still debated whether this was originally describing the chordae tendineae (tendons that anchor the heart valves and prevent them from inverting), or the tendons and nerves which were once believed to brace and sustain the heart. However, this historical perspective explains why the term is now used to describe a strong feeling of emotion. Yet these particular ‘heart strings’ have not been visualised in this way before.
The image was produced using a branch of magnetic resonance imaging (MRI) called diffusion tensor imaging (DTI). The technique tracks the diffusion of water throughout the myocardium (the heart’s muscular wall comprising interconnected sheets of muscle cells called myocytes). Due to the way the myocytes are organised, the movement of water is restricted, so tracking the location of water molecules can reveal valuable information about the structure of the heart in a non-invasive way.
The heart consists of four chambers: the left and right atria and the left and right ventricles. The upper region of the heart consists of the atria and the lower region is formed by the ventricles. It is the 3D helical alignment of muscle fibres in the left ventricle that is revealed by the image above. This region of the heart is responsible for pumping freshly-oxygenated blood around the body and, as a result, the muscular wall in this region is thicker than that of the right ventricle (which isn’t visible in the image due to the viewing angle).
‘Heart Strings’ was produced as part of a collaborative project by scientists at the University of Oxford. Dr Patrick Hales, one of the scientists involved from the British Heart Foundation Experimental Magnetic Resonance Unit at the Wellcome Trust Centre for Human Genetics, explained: “This technology allows us to model the prevailing structure of muscle cells throughout the heart and how certain pathologies, such as ischaemia, can cause this to change.” Also known as angina, ischaemia is a heart condition caused by reduced blood flow to the heart.
The wonderful impact of this image in revealing the fine structural detail of muscle fibres won the research team a runner-up prize in the British Heart Foundation’s Reflections of Research competition. However, for Dr Hales and his team the biggest reward is the knowledge that can be gained from images such as this. Hopefully in the not-so-distant future, computer models of the patient’s own heart will provide doctors with a diagnostic tool to help treat those unfortunates who receive the sharp, painful tug on their heart strings.
Dr Laura Pastorelli, Biomedical Images Coordinator, Wellcome Images