Infundibular reducer
Already in the early days of the Melody valve application Philipp Bonhoeffer was aware that indications were limited to a relatively small patient population. It was only in the last decade that the clinical importance of pulmonary regurgitation had been recognised. Pulmonary regurgitation is probably the single most important clinical problem in adults who survived childhood with congenital heart disease. Many of these patients do not have a conduit placed by the surgeon. Instead they either never had functional pulmonary valves or their valves were damaged by previous surgery. From an anatomical point of view this was a more difficult challenge.
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Facing this challenge Philipp Bonhoeffer decided to get in contact with the Istituto Politecnico in Milan in order to exchange his ideas with engineers. This was the beginning of a very unusual and fruitful collaboration. Philipp Bonhoeffer decided to include academic engineers directly into his clinical team dealing with valve implants. The engineers Silvia Schievano and later Claudio Capelli did their PhD research on this topic and began their career in biomedical engineering. They worked in close collaboration with the imaging department led by Prof.Andrew Taylor. This group, in association with the group of medical PhD students (Louise Coats, Philipp Lurz, Johannes Nordmeyer) conducted extensive research into the patient population which required pulmonary valves but did not have a previous conduit implant.
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Anatomical variations of the implantation site
In this project the valve could not be implanted in the known anatomy of a surgically implanted conduit but needed to face the large variety of anatomy existing in patients with all forms of congenital heart disease. The distensibility of the anatomic site could not be deduced from the available techniques of medical imaging but was of major importance to understand whether a stented valve could be anchored safely in the implantation site. Further muscular components of the implantation site could stress the valved stent to a degree that its functional integrity could be endangered over the long term. Clearly a viable approach to the pulmonary implantation for these patients would have had a major clinical benefit for a large patient population. To make the development of such a project attractive to medical industry the approach needed to be simple and not require a large amount of shapes and sizes of implantable devices in order to contain costs. The team developed virtual implantation techniques which could test theoretically designed devices and implant them in computer simulations in the true anatomy of patients gathered from either CT or magnetic resonance imaging. These modern approaches allowed to insure the best design of the device and significantly reduced the need to perform animal testing. Therefore bench testing and in vivo experiments had quickly given satisfactory results.
In 2008 Philipp Bonhoeffer was confronted with the clinical reality of one patient. An engineer in his early 40s who had been through a difficult medical saga. He was born with congenital heart disease and had faced numerous heart operations. At his last operation the surgeon needed to replace his mitral and pulmonary valve. The surgeon only managed to complete the mitral valve replacement but needed to abandon the full program of pulmonary valve replacement because of major surgical difficulty tied to the adherences related to the earlier surgeries. The patient had major difficulty to come through the post-operative course and remained severely symptomatic due to the absence of a functioning pulmonary valve after his surgery. Further surgery for the patient was ruled out for this young man who was father of two young children also with problems related to congenital heart disease. The patient was a good candidate for the technique developed by Prof. Bonhoeffer in association with the company Medtronic. After discussions with the multidisciplinary team of cardiologists, radiologists, cardiac surgeons and importantly biomedical engineers the decision was made to approach Medtronic for approval to give this last chance to the patient. Finally the patient was presented with the opportunity of such a procedure. This was now the third time Philipp Bonhoeffer was proposing to do a ‘first in man procedure’ and he wanted to apply his previously made experiences in order to provide the best possible care to the patient from a technical basis. Even more importantly he decided to involve the patient closely in the understanding of the thought process underlying the decision to propose the procedure.
The Team
Philipp Bonhoeffer felt privileged to deal with a patient of such high intellect with whom complex thoughts about technique and ethics of new procedures could be exchanged. When the patient demonstrated interest towards the procedure all regulatory requirements were dealt with and obtained. Philipp Bonhoeffer also approached the relevant ethical committee to whom he made unusual suggestions in terms of the consenting process which were enriched by the discussion and fully embraced by the committee.
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Philipp Bonhoeffer broke the standards of medical consenting.