Three-dimensional (3-D) printing is an emerging technology that is impacting the way cardiologists treat patients with congenital heart disease (CHD), according to a recent article published in journal of the American College of Cardiology JACC: Basic to Translational Science.
Congenital heart disease is the most common birth defect in the world, affecting nearly 1% of newborns (1). That’s a dire statistic in itself, but add to that the fact, about 1 in 4 infants born with CHD in the United States has chronic CHD requiring surgery or other procedures in the first year of life (2). Despite it being so common, patient management of CHD remains challenging due to its complexity and the diversity of etiologies (3, 4,5 ,6). As the cardiovascular morphology varies greatly between individual patients, different surgical options and patient managements are required for each specific case (3). For this reason, it is imperative to have a thorough understanding of the spatial relationship between the intra-cardiac structures, in order to decide the best surgical options (3, 5, 7, 8).
The use of 3D-printed heart models has improved the management of patients with congenital heart disease (CHD) on multiple fronts, from surgical planning and simulation to patient education. “The anatomical complexity and high-risk surgery involved with CHD care make it a prime candidate for the application of 3D printing,” says lead author Dr. Shafkat Anwar, a pediatric cardiologist at Washington University School of Medicine in St. Louis. He continues, "CHD interventions are high-risk procedures, and pre-surgical planning requires the mental reconstruction of complex 3D anatomic information. 3D printing provides a replica of the patient's anatomy. Using these models enables precise pre-surgical planning and simulation. This will hopefully improve patient outcomes.”
This is endorsed by Dr. Charles Huddleston, a pediatric cardiothoracic surgeon at SSM Cardinal Glennon Hospital and SLUCare in St. Louis. He tells us that up until recently diagnosis and management of CHD has relied on the review of flat, two-dimensional images acquired from echocardiography, cardiac magnetic resonance, and cardiac computed tomography (CT). Nonetheless, it is a very challenging task, first “translating two dimensional images into a three dimensional figure, and then mentally planning how to change the heart structure. Having a 3D model changes the game.”
Significant advances in 3D printing technology have made it possible to create lifelike, printed models of any part of the human anatomy, including congenital heart defects. These printed models help communicate the size, location, and degree of the defect and aid in developing patient-tailored surgical plans, allowing surgeons to anticipate potential complications and practice simulating the planned procedure along with the "plan B" "bailout" scenarios for high-risk surgeries. “Three-dimensional modeling prepares us by helping us know exactly what we’re going to do. We do not have to plan on the spot if we come across something unexpected. Instead we’ve had imaging from radiology as well and the model,” says Tamarah J. Westmoreland, M.D., Ph.D., a pediatric surgeon at Nemours Children’s Health System. “The surgery is almost like a musical concert. It is rehearsed, planned and then executed without complication.”
A common application in CHD is planning repair of a double-outlet right ventricle (DORV) requiring a complex intracardiac baffle (patch). This is typically a high-risk operation, Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery category 4 (9). The pulmonary artery and the aorta — the heart’s two major arteries, known as the “great vessels” — both connect to the right ventricle. In a normal heart, the pulmonary artery connects to the right ventricle, and the aorta connects to the left ventricle. DORV creates a problem because the right ventricle carries oxygen-poor blood, which then gets circulated in the body. Another heart condition, called a ventricular septal defect (VSD), always occurs with DORV. This is a hole in the tissue wall (septum) that normally separates the right and left ventricles. The VSD allows oxygen-rich blood to pass from the left ventricle to the aorta and pulmonary artery and out to the rest of the body. But even with this added oxygen, the body may still not get enough, causing the heart to work harder. That can lead to serious symptoms, like breathing problems or failing to gain weight. It can also cause serious complications. These include heart failure and high blood pressure in the vessels of the lungs. DORV surgery allows blood to flow out to the body and lungs normally. Medicines can help with certain symptoms. But only surgery can fix the problem.
Toddler with Dextrocardia, double outlet right ventricle, atrioventricular canal, s/p pulmonary arterial banding and Glenn shunt
The anatomy of DORV differs from patient to patient so that a thorough understanding of spatial anatomical structures is essential for the surgical management of DORV. Complex ventricular-arterial (VA) relationships in patients with DORV make preoperative assessment of potential repair pathways challenging. The relationship of the ventricular septal defect (VSD) to one or both great arteries must be understood and this influences the choice of surgical procedure (10). Construction of 3D models in patients with DORV is feasible and allows for extensive examination and surgical planning. This may facilitate a focused and informed surgical procedure and improve the potential for successful outcome.
In a recent prospective controlled study of twenty-five patients with complex DORV (3D printing group: 8 patients and a non-3D printing control group: 17 patients), Zhao and his associates at Department of Cardiovascular Surgery, Henan Provincial People's Hospital, Zhengzhou, China demonstrated that 3D printed models can accurately demonstrate anatomic structures and are of clinical benefit in the surgical management of complex DORV. There was good correlation (r = 0.977) between 3D printed models and CTA data. Patients in the 3D printing group had shorter aortic cross-clamp time (102.88 vs. 127.76 min, p = 0.094) and cardiopulmonary bypass time (151.63 vs. 184.24 min; p = 0.152), significantly lower mechanical ventilation time (56.43 vs. 96.76 h, p = 0.040) and significantly shorter intensive care unit time (99.04 vs 166.94 h, p = 0.008) than patients in the control group.
Models of structural congenital heart disease in children not only allow surgeons to rehearse and plan the approach for complex procedures but can also be used to train cardiac surgeons and residents to perform procedures, and teach structural heart disease to medical personnel, ancillary staff and families. For example, incorporating 3D printed models into a simulation-based congenital heart disease and critical care training curriculum improved 23 pediatric residents’ knowledge acquisition (p = .0082), knowledge reporting (p = .01), and structural conceptualization (p < .0001) of ventricular septal defects, as well as improved their ability to describe and manage postoperative complications at the Division of Cardiovascular Surgery, Children’s National Health System.
In a separate report, Olivieri and his associates at Children’s National Health System conclude that 3D heart models are effective in facilitating pediatric cardiac intensive care unit provider training for clinical management of congenital cardiac surgery. The seventy member team’s average response to whether 3D models were more helpful than standard hand off was 8.4 of 10; 90% of participants scored 8 of 10 or higher. Questions regarding enhancement of understanding and clinical ability received average responses of 9.0 or greater. Higher case complexity predicted greater enhancement of understanding of the surgery (p = .04).
3D models are also invaluable in explaining procedures to patients and their families. An echo, MRI or CTR can be difficult for a parent to conceptualize. Instead, the team at Nemours Healthcare System uses a true-to-size 3D model of that patient. In many cases, the patients have the high-fidelity models next to them in their room as care teams explain their treatment plan.
Figure 5. Infant with D-Transposition of the great arteries with large ventricular septal defect and hypoplastic pulmonary valve
Jessica Lewis is the mother of a Nemours patient and experienced this firsthand. Her 13-year-old son, Malachi, had a rare congenital coronary artery anomaly and needed cardiac surgery at Nemours.
“I was able to turn the model of my son’s artery around and look at it from all sides,” said Lewis. “The more educated you are about the procedure, the more empowered you feel because you completely understand what is going on with your child.”
“The ultimate viability of medical 3D printing will in large part depend on the impact it has on improving patient care,” concludes Dr. Anwar. “Obtaining the best outcomes requires impact at multiple levels, including patients and caregivers, individual clinicians, the medical team and healthcare system. 3D printing is a disruptive technology that is impacting each of these key areas in CHD...3D printing is rapidly evolving in medicine, with technical improvements in printers and software fueling new and exciting applications in patient care, innovation and research." As such, it is truly transforming the management of CHD.
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