Inside this Edition:

• Next Generation Tracking
• Smaller Aurora Sensor Coils
• Improved Neuroimaging
• AC vs. DC Technology
• Research Spotlight
• NDI Organizes for Research
• Events

Back to NDI InFocus July 2007

NDI Web Links:

• Medical Researchers

Robarts and NDI - Developing Minimally-Invasive Intracardiac Procedure

Today, many intracardiac procedures are conventionally performed through a median sternotomy and involve cardiopulmonary bypass (CPB). Although this approach provides generous surgical exposure, ample access to all cardiac structures, and an unobstructed view of the target region, the necessary preparatory procedures contribute to morbidity.

Naturally, minimally-invasive techniques are being developed in conjunction with technological advancements in an effort to reduce the surgical trauma of traditional open-chest procedures. The benefits to patients undergoing these new techniques include shorter hospital stays, less post-operative pain, and faster recovery times. Nonetheless, many of these techniques still involve CPB and cardiac arrest, and the associated costs and risks.

Dr. Terry Peters is the director of the Image-Guided Surgery Program at the Robarts Research Institute (London, Ontario, Canada). Dr. Peters' group, along with colleagues Dr. Gerard Guiraudon (cardiac surgeon), Dr. Doug Jones (electrophysiologist) and Dr. Dan Bainbridge (anesthesiologist), are developing an exciting and novel technology that allows minimally-invasive interventions to be performed inside the beating heart. This is accomplished by constructing a visual representation of the surgical environment by combining intraoperative ultrasound (US) imaging with virtual reality (VR). Readily available 2D and 3D cardiac US imaging technology is used such as trans-esophageal echocardiography (TEE) and intracardiac echocardiography (ICE).

The position and orientation, in all six degrees-of-freedom, of the US transducer and each surgical instrument is determined in real-time by the Aurora system, through the attachment of a miniature sensor to each device. Access to the heart is gained via a mini-thoracotomy.

Dr. Peters' team is evaluating their new procedure with respect to implantation of an artificial mitral valve. The first stage was to assess the accuracy of the technique using a cardiac phantom.

Experienced cardiac surgeons, using 2D US guidance alone, were often several millimetres off target with the placement of the valve prosthesis (see Figure 1). Placement was consistently on target with the addition of the VR environment (see Figure 2).

Animal studies are now underway in a clinical setting (see Figure 3), and so far have demonstrated the feasibility of the process. Placement of the artificial mitral valve has been reasonable, but it is still too early to report many specific results. A great deal of work remains to be done, but the early series ofexperiments has convinced Dr. Peters and his team that open-heart, on-pump surgical procedures can be replaced with less invasive interventions inside the beating heart in which a VR environment is a key element.

References:
1. C. Linte, A. D. Wiles, J. Moore, C. Wedlake, N. A. Hill, D. Bainbridge, D. Jones, G. Guiraudon, and T. M. Peters, "Augmented reality-guided intra-cardiac intervention" in Proceedings of SPIE, Medical Imaging, Visualization, Image-Guided Procedures, and Display, 6509, Feb. 2007.
2. J. Moore, G. Guiraudon, D. Jones, N. A. Hill, A. D. Wiles, D. Bainbridge, C. Wedlake, and T. M. Peters, "2D Ultrasound Augmented by Virtual Tools for Guidance of Interventional Procedures" in Proceedings of Medicine Meets Virtual Reality 15, Feb. 2007.

Questions, Concerns, Complaints

If you have any questions, concerns, complaints, or if you think there is an error with your subscription, please feel free contact us at infocus@ndigital.com.