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Innovation is the operative word at the Montreal Heart Institute, in every sphere of cardiology, medical imaging, pharmacogenetic research, interventional cardiology, and heart surgery.
Founded in 1954 by Dr. Paul David and affiliated with the Université de Montréal, the MHI is a highly specialized centre dedicated to tertiary and quaternary care, cardiovascular disease prevention, as well as teaching and research.
The MHI is a Canadian world leader in its field and a much sought-after partner. Its mission also includes the development and evaluation of new technologies and new forms of intervention in the field of cardiology.
The MHI is now planning to expand its surgery department to seven operating rooms equipped with the latest technology in the areas of service management and delivery, as well as audio-visual integration and telemedicine. The planning of the new surgery department provides an excellent opportunity to examine current technology and to consider future standards in cardiac surgery. It is in this context that we present a few specific innovations in the field of cardiac surgery
In recent years, the field of cardiac surgery has seen the emergence of new, less invasive techniques, which improve the quality of surgical techniques through enhanced visualization of cardiac structures, and also reduce postoperative pain and complications, thus improving patient recovery. The MHI plans to introduce minimally invasive endoscopic mitral valve surgery at some point in 2006. The equipment required for such surgery is similar to laparoscopic equipment, except that the endoscope is kept in place with a supporting device and the surgeon must work with an instrument in each hand. The challenge consists of performing cardiopulmonary bypass procedures percutaneously. Instead of using an external aortal clamp, the aorta is obstructed with an inflatable balloon. An indispensable component of the procedure is the use of transesophageal echocardiography to verify the position of the balloon in the aorta.
One of the operating rooms will be dedicated to research and development and will have a robotic surgery system for use in performing minimally invasive procedures (such as repairing mitral valves). Robots can perform more minute surgical gestures with a far greater degree of surgical freedom than human surgeons.
The robotic surgical system comprises a command console for the surgeon and the robot itself. The robot is equipped with three robotic arms fitted with an endoscope and surgical instruments. It is designed to perform its work through small intercostal incisions. One robot arm introduces a 3-D camera into the thorax through the first (central) incision, while the other arms, which are fitted with minute cardiac surgery instruments, reach the surgical field through the other incisions.
The cardiac surgeon “operates” from the console via two manipulators. A computerized system conveys the surgeon’s movements to the robot arms, after filtering out any tremors associated with fatigue. A screen enables the surgeon to visualize three-dimensional images of the operating field provided by the endoscope.
Cardiopulmonary bypass (CPB), which can lead to postoperative complications by activating the immune system and the inflammation cascade, is also changing. A study to assess so-called mini-circuit CPB is currently underway.
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In some cases, the mini-circuit CPB is actually replacing conventional CPB methods. The mini-circuit approach is designed to reduce the volume of extracorporeal blood by eliminating, among other things, the blood storage reservoir and reducing the total length of the circuit. Moreover, the circuit is entirely closed. The system aspirates the patient’s blood through a weakly hemolytic centrifugal pump; as a result, the oxygen machine can be placed at patient height. The system is small, approximately two-thirds of the size of a conventional device, and can be placed very close to the patient. A smaller circuit requires less priming solution and therefore less hemodilution. The circuits are coated with an antithrombogenic solution to protect the heart against inflammatory reactions.
The MHI is also contributing to progress in hybrid procedures that call on the expertise of both cardiac surgeons and interventional cardiologists to treat pathologies of the thoracic aorta percutaneously under fluoroscopic guidance. We also implant thoracic aorta endoprostheses. Recently, a new type of aortic valve was implanted percutaneously in a patient who was unable to undergo a conventional operation – the first valve of this type to be implanted in North America.
Hybrid procedures require an operating room environment that combines life support equipment, rigorous asepsis and high-performance angiography equipment. The hybrid operating room is a conventional catheterization room designed to accommodate the instruments normally found in an operating room (anesthesia equipment, ECG equipment, heart-lung machine, etc.).
The room must also be designed to accommodate ceiling-suspended equipment, an arrangement that creates a more comfortable environment for the patient. These rooms are equipped with articulated arms and integrated audio-visual systems so that considerable space is gained. In order to adapt to conventional forms of heart surgery, the room must also have an operating table in addition to an imaging table, since the latter is not suitable for conventional surgical procedures.
The field of ventricular assistance is also rapidly growing due to the difficulty in recruiting cardiac transplant donors. Ventricular assistance is achieved by installing a fairly large internal or external artificial valve which is controlled pneumatically or electromagnetically. New, completely implantable systems will soon be available in Canada. These consist of a rotating axial turbine, which is implanted directly at the apex of the left ventricle, with a single outflow conduit to the descending thoracic aorta. Cardianove Inc., the company created when MHI surgeons joined forces with engineers from the École Polytechnique de Montréal, is currently developing a miniature pump that will be entirely implantable in the heart as a treatment for heart failure.
In tertiary cardiology, technological innovations abound, supporting as well as generating, new practices in cardiac surgery. In this context of constant change, the operating room of the future will need to be designed for versatility and adaptability in order to accommodate new technologies and new surgical practices.
Sophie Le Bail M.Sc.A, Biomedical Technology Consultant, Montreal Heart Institute
http://www.icm-mhi.org
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