3-D printing for endovascular surgery

The traditional model of medical education — a mix of studying theory and of apprenticeship — has severe limitations in the field of neurological surgery. In other fields, notably aviation, simulations of conditions and scenarios are an important component of training. Unlike airplanes, however, no two human patients are alike. Even a single pathological process can be expressed differently in individual patients, mitigating the effectiveness of simulated standard scenarios as preparation for real clinical cases.

At Mayo Clinic in Rochester, Minnesota, neurologic surgeons practice complex vascular surgeries on models that exactly replicate an individual patient's aneurysm. The models are generated by 3-D printers, based on extensive imaging of a patient through angiogram and PET scan.

"This is an incredibly effective way for us to rehearse a specific case and choose the appropriate device. In the model, you can practice different scenarios until you find the approach that works best. It is very close to real life," says Giuseppe Lanzino, M.D., a consultant in Neurosurgery at Mayo Clinic's campus in Minnesota.

Each custom-printed model incorporates fluid that mimics blood flow through the patient's aneurysm. The models are currently being used in conjunction with an ongoing national trial of a new device for treating intracranial aneurysm. Simulations can be particularly helpful in the context of new medical devices.

"In the old days it was accepted that there is a learning curve," Dr. Lanzino says. "But as surgeons, we should be able to provide to patients the same experience. It shouldn't matter whether that patient is our first case with a particular device or procedure, or our thousandth case."

He contrasts his experiences with two cases involving the new device. In the first, the surgical team practiced placement of the device — which the team had never used before — into a 3-D printed model before the actual surgery. Later that day, Dr. Lanzino implanted the device in a second patient without first practicing on a model because the second patient required urgent treatment.

"In the first case, we knew what we were going to find and what we needed to do, even though it was the first such device we had implanted," Dr. Lanzino says. "The second procedure — even though we already had experience from the first surgery — was not so straightforward, although ultimately successful."

The 3-D printed models have potential to guide surgeons in a variety of endovascular procedures. Jonathan M. Morris, M.D., and Jane M. Matsumoto, M.D., both consultants in Radiology at Mayo Clinic's campus in Minnesota, have used 3-D printing to create patient-specific preoperative models for rehearsing complex thoracic and abdominal aortic aneurysm endovascular repair.

"Although there have been several advances in imaging capabilities over the past decade, we are still limited by having to display the images statically. The exact morphology of complex neuroanatomical relationships cannot be easily understood in this way," Dr. Morris says.

"Three-dimensional printing allows us to re-create patient-specific anatomy and rehearse procedures on models that are the exact dimensions of what will be encountered at surgery or endovascularly. This not only allows the planning of novel devices tailored to the individual but also increases the surgeon's confidence, and aids in the education and consent of the patient."

Adds Dr. Lanzino: "In our field there has been a lot of discussion about how we can minimize risks to patients. This use of 3-D printing is really a major advance in medical procedures with potential to become standard in the near future, especially for less common conditions and newer operations."