Aortic Valve Stenosis
Patient-specific medical models are revolutionizing how surgeons plan and practice complex procedures. In this case study, we explore how we developed a 3D-printed heart model to assist in the treatment of an 84-year-old woman suffering from severe aortic valve stenosis.
The aortic valve, located between the heart's left ventricle and the aorta, ensures blood flows properly from the heart to the rest of the body. When this valve narrows, the heart has to work harder to pump blood, which can weaken the heart over time. Known as aortic valve stenosis, this condition can cause significant symptoms, such as chest pain during physical activity, shortness of breath, fatigue, dizziness or fainting spells, and an abnormal heart murmur. For our 84-year-old patient, shortness of breath, fatigue, and difficulty walking short distances greatly affected her quality of life.
Aortic valve stenosis is often caused by age-related scarring and calcium buildup on the valve. Other causes include rheumatic fever in childhood or a congenital defect where the valve has only two cusps instead of the normal three. For advanced cases, valve replacement is the only effective treatment.
The cardiovascular surgeons treating this patient chose to perform a Transcatheter Aortic Valve Replacement (TAVR), a minimally invasive procedure that replaces the diseased aortic valve with an artificial one. During TAVR, a cardiologist guides a catheter through a blood vessel in the leg to the heart. The replacement valve, folded tightly for delivery, is inserted into the old valve. Once expanded, it pushes aside the old valve’s flaps and takes over its function. The procedure takes about two to three hours, and patients typically recover quickly, with less pain and shorter hospital stays compared to open-heart surgery.
To prepare for this procedure, the surgical team requested a 3D-printed model of the patient’s heart to visualize the anatomy and plan the intervention. The team specified that the model must include a one-to-one representation of the left heart, comprising the left ventricle, mitral valve, aortic valve, aortic root, and ascending aorta. The model needed to be modular, allowing access to the left ventricle to view the aortic valve from inside. It also had to be made from soft and flexible material to mimic heart tissue.
The first step in creating the model involved segmenting the structures of interest from the patient’s CT scan. The CT images were cropped to isolate the heart, with a layer spacing of 0.5 mm to ensure fine detail. Nine labels were created to mark key structures, and the "grow from seeds" algorithm was used to highlight these areas. After adjustments, the segmentation data was converted into digital 3D models.
Next, the digital files were refined using Meshmixer software. Any errors, such as holes or disconnected sections, were repaired, and the surface was smoothed to replicate the texture of heart tissue. Most of the segmented structures represented the inner lumen of the heart's cavities, which were made visible during the CT scan using a contrast agent. The modular design was finalized, ensuring the model met the surgeons’ requirements.
An additional validation step was introduced to ensure accuracy. The final 3D model was reimported into the imaging software and overlaid with the original CT images. This process confirmed that the model was a precise one-to-one replica of the patient’s anatomy, with details as fine as the 0.5 mm layer spacing of the CT scan.
The digital model was then brought to life using Digital Light Processing (DLP) 3D printing technology. This method uses a photosensitive resin that solidifies when exposed to light, enabling high precision. A flexible resin with a Shore A30 hardness was selected to replicate the soft properties of heart tissue.
The entire process, from CT analysis to the final printed model, took just 12 hours. The surgeons commended the model for its accuracy and usefulness, stating:
"The model illustrated the anatomical situation and the significant stenosis of the aortic valve. The position and guidance of the catheter and the artificial aortic valve could be demonstrated and reviewed on the model, providing better understanding for everyone involved."
By allowing the surgical team to practice the procedure in advance, the model helped reduce time in the operating room and increased the confidence of everyone involved.
This case highlights the potential of patient-specific models to improve outcomes for complex medical procedures. At HumanX Medical LLC, we are proud to contribute to advancements in surgical precision and patient care.
If you have an interesting case that could benefit from a 3D-printed model, we’d love to hear from you!