Biomedical engineering

The focus of Biomedical engineering is in particular the imaging and diagnosis of cardiovascular disorders. This department is led by Prof. Dr. Ir. A.F.W. van der Steen. The Biomedical engineering department brings together two technical specialisms of the Thoraxcenter, namely:

• In the Hemodynamics group the emphasis lies on the biomechanics of the heart and blood vessels. The projects within this group all have a clinical orientation.
• The Experimental Echocardiography group investigates the physical and technical aspects of ultrasound for cardiac diagnosis. Further information

Echography is the most commonly used imaging method in medicine. The experimental cardiology group develops equipment for echocardiography (for example new transducers) and carries out research into the properties of ultrasound. Part of this research focuses on contrast echocardiography to display the flow pattern of the blood in the heart chambers and the circulation in the heart muscle. Blood is a poor reflector of ultrasound. With a contrast medium the reflection of the ultrasound through the blood pool can be improved. Such a contrast medium consists of micrometer-sized bubbles that reflect ultrasound very efficiently. The bubbles consist of air or an inert gas and are encapsulated with a thin layer of protein, fat or polymer to prevent them dissolving. These contrast bubbles are injected into the arm of the patient to be examined and they are so small that they are carried by the blood into the smallest capillaries. Echocardiography then shows which part of the heart muscle has poor or no circulation. In addition to these perfusion measurements there is a growing interest in using these bubbles for therapeutic applications. In this case the bubble is used to carry a medicine. The bubble then releases the medicine on the site e.g. of a tumor, under the influence of ultrasound. Vibrating microbubbles can also be used to increase the permeability of the cell. The microflow around the bubbles changes the shear stress that the cell "feels", and makes it possible for bigger molecules to pass through the cell membrane. In order to study both the bubble dynamics and the interaction of bubbles, cells and ultrasound, together with the University of Twente a digital high-speed camera has been developed that can take 25 million pictures per second (a normal video camera can take 25 pictures per second). This high-speed camera has been named after the famous fire tower "de Brandaris" on Terschelling, because the principle is based on a rotating light beam and is unique in the world. The camera has been operational for a year and has already produced spectacular results and new understanding, such as the complex interaction between cells and bubbles and jets that are produced after the gas escapes from the capsule. There are high expectations and the mechanisms still to be discovered will without doubt lead to better perfusion measurements and new therapeutic applications.