3D printing may help predict paravalvular leaks prior to TAVR
The use of 3D printing prior to transaortic valve replacement (TAVR) procedures may help cardiac surgeons to predict areas where an ill-fitting stent frame could lead to paravalvular leaks (PVLs), a small retrospective study has shown.
PVL is a relatively common issue that results from an ill-fitting valve, with a huge impact on mortality related to cardiac surgery. Interventionalists have been trying for years to improve the success rate of TAVR procedures by preventing PVLs. “We’ve made huge improvements in reducing PVL … but there are still significant barriers with some of the self-expandable valves,” said lead author Dr Sergey Gurevich, a cardiologist from the Minneapolis Veterans Affairs Health Care System and the University of Minnesota in Minneapolis, US.
Even with the 3D multislice computed tomography (CT), TAVR operators may have a difficult time predicting which patients will have PVL and if it will be mild, moderate, or severe PVL. “We rely on valve technology to assist us,” Gurevich said. “It would be nice to know what to expect before we go in to help us with the valve selection.”
Patients enrolled in the study were undergoing TAVR for severe calcific aortic stenosis and particularly at risk for PVLs. Pre-procedure CT images were analysed to create 3-D printed models of each patient’s aortic root. The models were then implanted with the Sapien XT valve each patient received. Five had the 26-mm valve, and one a 23-mm valve. [SCAI 2018, abstract III-02)
The researchers then compared a re-scan of the implanted models with echocardiograms from the patients taken after TAVR. In every case, the 3D printed model predicted the PVL seen on echocardiograms, suggesting that if the modelling had been done pre-TAVR procedures, the PVLs could have been prevented in these patients.
Significant calcifications identified on pre-TAVR CT were associated with areas of poor stent apposition in most cases. At least two patients with central aortic insufficiency were predicted to have patient-prosthesis mismatch – one had received the 23-mm XT valve, while the other had a body surface area of approximately 3 m2 which is higher by 50 percent than the average.
“We’re very encouraged to see such positive outcomes for the feasibility of 3D printing in patients with heart valve disease,” said Gurevich. Patients are at a high risk of developing PVL after TAVR … anything we can do to identify and prevent these leaks from happening is certainly helpful. As 3D printing evolves, we hope to see an increase in accessibility and opportunity for the use of this technology to help improve patient care.”
Gurevich’s group is currently working on building a library of aortic valve geometries to quantify the amount of leak anticipated during TAVR. The ultimate goal, he said, is to pave the way for personalized aortic valves and extend this approach to other structural interventions, including left atrial appendage closure devices and mitral valves.