VIDEO: CT imaging for TAVR and TMVR structural heart interventions

He was among the experts that led a packed day-long workshop at SCCT on pre-procedural imaging workups on transcatheter aortic valve replacement (TAVR) and TMVR. 

"While TAVR has become commonplace, TAVR has also become a lot more complicated," Cavalcante said. "Yes, TAVR is straightforward, but now we have expanded indications with bicuspid valves, we have valve-in-valves, and we have post TAVR followup."

He said the workshop organizers, which included a few of the top imagers in the field, realized by 2 p.m. they had not even gotten to the mitral valve. That told them the field is now completely on its own and has outgrown a single-day course to cover both valves. "The learning lesson for us was that we can now separate the valves into their own day-long sessions," he said.

Mitral valve LVOT issues can be assessed with CT

In the mitral valve space, Cavalcante said there is now an indication for the Sapien TAVR valve to be used in the mitral position as a replacement valve in high-risk surgical patients. However, there are issues that come with using that valve in the mitral position for which it was not designed for. The biggest issue for imagers in pre-procedural CT screenings is to assess patients to see if they can receive the valve, as the long overhang of the valve skirt into the ventricle can cause LVOT obstruction. This is critical because LVOT obstruction can cause serious blockage of flow and cause adverse hemodynamics leading to poor outcomes or death.

In addition to LVOT obstruction, imagers now also calculated the area of the Neo-LVOT, because this number can predict poor outcomes in patients and help decide it the valve or ventricle need to be modified to make more room for the valve implant and ensure good hemodynamics. 

"Imaging plays a critical role for the procedure's success," Cavalcante said. "The Neo-LVOT is one of the key pieces that we do in the analysis. The other piece too that were are starting to learn is at what part of the cycle do you evaluate the Neo-LVOT? Do you do it at very end systoly when there is no more blood and the ventricle is the smallest? Yes, we like to be a bit conservative and that would be the worse case scenario, but that measure could be rejecting a lot of potential patients that you could still treat. So we are still learning and finding that maybe changing that neo-LVOT area, rather than a single cutoff, might be better."

New transcatheter procedures have been developed to modify the valve area and increase the real-estate to place these valves, Cavalcante said. This includes cutting the native leaflet using a LAMPOON (Intentional Laceration of the Anterior Mitral leaflet to Prevent left ventricular Outflow ObstructioN during transcatheter mitral valve implantation) procedure prior to the prosthetic transcatheter valve implant to enable better blood flow. Another method is the SESAME (septal scoring along the midline endocardium), which uses an electrified wire to trim tissue on the septum to create more room for the valve. Radiofrequency ablation and alcohol septal ablation also can reduce the size of the septum. All these procedures require pre-planning and enable more patients to be treated, he said. 

Cavalcante also discusses the need for automation of measurements in structural heart and the deeper involvement of radiology at hospitals without dedicated cardiac imaging programs.