Towards a better characterization of hypertrophic hearts

Study investigates Ingestion of caffeine on the efficacy of drugs commonly administered to patients referred for cardiac magnetic resonance.

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Transesophageal echocardiogram (TOE) is a key imaging approach routinely used to guide the minimally-invasive treatment of many forms of heart disease.

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Hypertrophic cardiomyopathy (HCM) is a condition where the heart muscle becomes thickened. This condition affects about one in 500 people.

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The aim of the project is to develop a commercially available 3D ultrasound technique for accurate measurement

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Hypertrophic cardiomyopathy (HCM) is a condition where the heart muscle becomes thickened. This condition affects about 1 in 500 people. Sometimes it is present at birth and it can develop in young children. Most people with this condition do not have any symptoms, but a small number of sufferers undergo a sudden collapse and death. It is very important to be able to correctly identify people with HCM and risk of sudden cardiac death.

Clinicians currently try to diagnose this condition based on:

Once the diagnosis is confirmed, other tests may be needed to assess the severity of the condition. A useful tool in this case is the doppler ultrasound scan which looks at blood flow through the outflow and inflow vessels of the hearts chambers.

In this project we investigate novel imaging and computational models to improve how we can identify the hypertrophic heart. The objective is to develop more accurate measurement methods to describe the shape and the function of the heart. Being able to quantifymore accurately specific parts of the heart’s structure will improve the identification of patients at a higher risk of complications or sudden cardiac death. Following improved identification there is also the possibility of personalised treatments.

Harnessing the rich information of anatomical medical images

A key sign of a hypertrophic heart is that the heart walls get thicker, which makes the heart chambers irregular in shape. Clinicians capture detailed anatomical images which are used to find the maximum thickness of the heart wall. If the maximum value of wall thickness is greater than 15mm, the patient is diagnosed as having HCM. This is a durable and simple metric, but doesn’t take advantage of the wealth of information available in medical images. Our motivation is to harness this information in order to lead to a much more comprehensive and powerful measurement that informs doctors about the characteristics of the heart’s shape. The difference in shape compared to a regular heart and the irregular thickening of the heart walls are signs of the underlying disease process that inform about the disease progression and the risks of each subject.

Fig. 1: Automatic reconstruction of the 3D anatomy of the left ventricle of the heart for the construction of a computational statistical atlas.

Researchers at King’s College London are at the forefront of the development of the tools to capture and analyse the shape of cardiac anatomy. Tools called “Computational statistic atlases” are used for these studies. They can reveal subtle differences between the 3D shape of subjects hearts that otherwise would not be identified through traditional clinical studies [1]. The construction of such atlases requires a collection of medical images from different subjects that represents the range of changes experienced in good health and patients suffering from heart disease. Automatic and reproducible methods are used to reconstruct the 3D anatomy of each subject [2], [3], and statistical tools are applied to reveal the variation and to describe each case by 3D shape measurements.

Comprehensive flow images to reveal accurate pressure differences

One possible adverse effect of HCM is the creation of an obstruction for the blood when it leaves the heart. This introduces an additional burden every time the heart beats that may lead gradually to heart failure. In order to characterise this obstruction, doctors use doppler echocardiography to observe the velocity of the blood flow when it leaves the heart. They can then infer the blood pressure difference between inside and outside the heart. This approach is not invasive as it does not require any sensor being placed inside your heart to measure pressure. But the technique is limited by the low accuracy in the estimated pressure.

Researchers at King’s College London are developing an alternative and much more accurate non-invasive approach to measure the blood pressure differences. Advanced Magnetic Resonance Imaging protocols are able to capture 3D information of the blood flow, with computational techniques they are used to reveal the blood pressure differences in time and space [4], [5]. These techniques will offer a more accurate description of the obstruction caused by HCM, and therefore enable a better identification of the stage of the condition and best treatment options.