Sandrine Debecker April 15, 2016

Despite careful planning, the complex dimensions of the left atrial appendage (LAA) and its variable morphology can result in procedural failure. To make their pre-operative planning even more thorough, a team of Australian physicians from the Victor Chang Cardiac Research Institute in Sydney turned to medical 3D Printing. The team created an exact replica of a patient's heart while planning a LAA closure procedure with a Boston Scientific Watchman™ device.

In preparation for the procedure, the researchers used Materialise Mimics to segment the CT data of the left atrium and LAA. They then generated a digital 3D model that was printed in a flexible material to simulate atrial mechanical properties.

Visualizing LAA closure

Analysis of the LAA deformation after a 24-mm Watchman deployment. Image courtesy of Dr. James Otton.

The 21-mm, 24-mm, and 27-mm Watchman devices were deployed into the 3D-printed heart model, which was subsequently re-imaged with CT. Afterwards, they used the software to analyze the imaged 3D-printed model and calculate the anatomic deformation for each device. This helped the investigators to identify the areas and extent of engagement of the device on the flexible atrial model.

Interestingly, based on the TEE (transesophageal echocardiography) data, the team reports that the 21-mm device would have been selected, but the data from the re-imaged CT scan of the 3D-printed model suggested it would have been too small. Besides, data from the 3D model showed that the 27-mm Watchman device was too large to be selected for the patient. As a result, the 24-mm device was chosen and successfully deployed.

Dr. James Otton and his colleagues published the data on their experience with 3D Printing of the left atrial appendage in a letter to the editor in the Journal of the American College of Cardiology: Cardiovascular InterventionsAccording to the researchers, medical 3D Printing is particularly relevant to LAA occlusion where the patient’s anatomy is complex and the interaction between the device and the appendage is difficult to quantify, even using advanced imaging methods.

Otton concludes: “Calculating measurements using CT and TEE to appropriately size the Watchman device can be difficult, but with a 3D-printed model you have immediate feedback an understanding of ideal sizing.”

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Visualzing LAA closure: Watchman device in a 3D-printed LAA model
Watchman device in a 3D-printed LAA model. Image courtesy of Dr. James Otton.