Features

As cardiovascular disease has increased globally in recent decades, clinical demand for transesophageal echocardiography (TEE) has risen along with it. In TEE, a clinician inserts an ultrasound probe by mouth and guides it through the esophagus to capture images of the functioning heart. The procedure is commonly used by cardiac anesthesiologists to monitor patients undergoing surgery and in intensive care—as well as by imaging specialists to diagnose valvular heart disease.

Fig. 1 – Shown is a manikin that can be used to perform a simulated transthoracic echocardiogram exam.
Gaining proficiency in performing a TEE exam requires extensive hands-on training that, until recently, was primarily acquired through observation and supervised scanning of patients in real-life situations. In addition to knowledge of cardiac anatomy and the technical skills required to successfully guide the probe to gain desired views, clinicians must be able to interpret the flat, 2D ultrasound images in the context of the 3D structures of the heart.

Now students and trainees can gain the necessary hands-on experience without risk to patients with a simulation system known as HeartWorks. It was developed in the UK through a partnership between cardiac experts and digital animation experts.

How It Began

The project got its start in 2006 when three cardiac anesthesiologists at University College London Hospitals (UCLH), Drs. Sue Wright, Andrew Smith, and Bruce Martin, were searching for a tool that could improve their teaching of heart anatomy. Their idea of creating a virtual heart, and a chance conversation, led them to contact Glassworks, an award-winning visual effects company with a strong track record in taking on unusual projects.

A team of artists and developers at Glassworks set to work building an accurate understanding of what a functioning human heart looks like by collecting digital heart images and watching an open heart surgery in progress. As that took place, the clinicians worked with surgeons, cardiac morphologists, and other experts to refine the modeling. By 2008, they had created a realistic, anatomically accurate, animated model of a human heart that is fully interactive.

Early in the development phase of this virtual heart, the three clinicians realized they could use it to generate a simulated ultrasound image, making it a valuable training tool. By displaying the actual and simulated images side-by-side, students would be able to understand both the structure of the heart and also the way in which echocardiography images are derived from it.

Fig. 2 – The virtual heart is displayed on a computer monitor next to a simulated ultrasound image generated from it.
The original goal of the project was to produce only this virtual heart and simulation software, but as the system took shape, they realized it could be combined with a realistic manikin to provide hands-on experience for trainees. Asylum Models, a commercial model-making company, created a life-size rubber torso of a manikin to round out the package. The manikin could be used to gain the practical skill of acquiring echocardiogram images through a simulated TEE exam. Later a manikin that could be used for performing a simulated transthoracic echocardiogram (TTE) exam was added. (See Figure 1)

In 2008, Inventive Medical Ltd. (IML) was formed to develop the intellectual property now owned by the company and to commercialize and support HeartWorks. IML now integrates, installs, and supports HeartWorks for medical schools, hospitals, and medical device companies across the world.

How It Works

At the core of the HeartWorks system is a highly realistic, interactive, computer-generated 3D model of the human heart that has been animated to simulate human cardiac motion. The virtual heart is displayed on a computer monitor next to a simulated ultrasound image generated from it. (See Figure 2)

A key to the success of this technology is the use of tiny electromagnetic sensors by Ascension Technology, Milton, VT, that are embedded in the model ultrasound probe. The sensors track the position of the TEE probe head in real time, in much the same way that a GPS system can track the location of a moving object. Ascension makes 3D tracking devices for medical guidance, real-time visualization, and minimally invasive surgery and target acquisition.

“We initially chose Ascension sensors because we perceived them to have an unrivalled technology, which they do,” said HeartWorks Chief Executive Ian Whittaker. “As we launched activity with Ascension, we were hugely impressed with their engineering support and desire to work with us to optimize the HeartWorks solution for our customers. It has developed into a true partnership relationship.”

Just as in a real-life TEE exam, the probe can be moved up or down and rotated through different planes of viewing. With the aid of the sensors, the resulting side-by-side display of the virtual heart and the ultrasound image allows the trainee to clearly visualize the relationship between the 2D TEE image on the screen and the underlying 3D anatomy of the heart. Throughout the simulated procedure, the virtual heart continues to beat and its constituent parts behave realistically.

Where It Stands

The HeartWorks system is being used in more than 30 countries across the globe to train cardiac anesthesiologists and other cardiac specialists. Measure ment capabilities have been added, including M-mode and Color Doppler. A student assessment package is currently under development.

As the HeartWorks system continues to develop, IML is now focused on extending the range of pathological models it offers that simulate hemodynamic disturbances in typical cardiac diseases. In addition, the recent launch of a web-based eLearning system called “A Complete Introduction to Transesophageal Echocardiography,” in conjunction with The American Society of Echocardiography, has proved to be an invaluable learning tool for those wishing to expand their knowledge of echo cardiography.

This article was supplied by Inventive Medical Ltd., London, UK. For more information on the HeartWorks system, visit http://info.hotims.com/45602-168. For more information on Ascension Technology, visit http://info.hotims.com/45602-185.