麻豆传媒

SAN DIEGO -- A bevy of new technology for transcatheter approaches to heart disease showed early promise in solving durability and safety of devices and their implantation, researchers reported here.

A session on innovation at the Transcatheter Cardiovascular Therapeutics (TCT) conference provided a rundown of technology in the works.

Polymer Valves

While current valve replacement devices are made out of materials that eventually wear out, ideally "we would like to have one valve for life," noted Christian Spaulding, MD, PhD, of the European Hospital Georges Pompidou in Paris.

He reported on a polymer material used to make valves that resorb into the body after endothelialization to leave behind an endogenous leaflet (Xeltis).

In aortic applications, the material is still in preclinical studies, with good hemodynamic performance throughout 12 month follow-up in three of the five configurations tested in sheep, and no tears or perforations and "minimal thrombus." The first human studies are likely to be done with surgical aortic valve procedures, Spaulding noted.

A first-in-man study in 12 patients with congenital heart disease using the material for right ventricular outflow tract replacement is ongoing, he noted, with preliminary results showing primary endpoint was met and no reoperations or reinterventions were needed up to 18 months.

An advantage over current animal tissue valves used is that the polymer material is scalable to any size, which should greatly expand durability for growing children and the proportion of children eligible for a transcatheter procedure, rather than repeated open-heart surgeries for cadaver tissue implantation, added Henri Justino, MD, of Baylor College of Medicine in Houston and chief medical officer for the developer, PolyVascular.

It has sufficient coaptation to carry patients from early childhood to near adolescence, then serve as a landing zone for an adult valve, he said at the TCT session.

Leaflet Laceration

Intentional laceration of the bioprosthetic or native aortic scallop during transcatheter aortic valve replacement (TAVR) for patients at high risk of coronary obstruction was associated with a 0% rate of coronary obstruction, according to preliminary results from the BASILICA early feasibility study.

All 35 leaflets targeted in 30 patients were successfully lacerated with the technique, which involves looping, lifting, and splitting the leaflet. But there were two failed attempts at traversal (chalked up to early techniques that have been updated), for a primary technical success rate of 93% on a per patient level.

All patients survived and had a successful first TAVR device implantation without any emergency surgery or intervention related to TAVR with leaflet laceration, reported Jaffar Khan, MD, of the National Heart Lung and Blood Institute (NHLBI) and Medstar Washington Hospital in Washington.

In terms of safety among the patients studied -- all at high or extreme risk for surgical aortic valve implantation who were getting TAVR for native severe aortic stenosis or bioprosthetic valve failure -- "hemodynamic instability was uncommon," with a 10% rate of hypotension that resolved promptly with TAVR.

One of the patients (3%) died after multi-organ failure and two (7%) had a stroke, "which may be related to multiple catheter manipulations, leaflet calcification, and relative immaturity of the technique, or to balloon valvuloplasty and TAVR," Khan suggested.

He concluded that the technique warrants a larger trial, performed only in centers with "appropriate proctoring and experience."

"The true incidence of coronary obstruction does seem to be low, although the threat of coronary obstruction is high. If you think of all the cases that are out there where a guide, a wire, a stent are put in, it's certainly a much larger denominator than those that actually obstruct," noted co-investigator Adam Greenbaum, MD, of Emory University in Atlanta, speaking from the discussion panel at the TCT session.

"But with relatively little risk, relatively few complications as you can see in the feasibility study, the question is why wouldn't you cut the leaflets? I think if there was any risk perceived at all" he said, adding: "There may be other benefits to getting the leaflets out of the way, sinus washout, for example. Do you really want those leaflets there? The surgeon doesn't leave them behind, why should we?"

Embolic Protection

While the Sentinel device approved for embolic protection during TAVR covers two of the three cardiac outflow tracts, two novel devices to cover all three heart valves during TAVR were presented.

The CAPTIS device has an aortic arch deflector shield covering all three vessels, and a filter with pockets to capture debris that could head to the kidneys, reported Giora Weisz, MD, of Montefiore Medical Center in New York City. So far it has been tested in pigs.

The third generation TriGUARD device similarly has a mesh that covers all three outflow vessels, eliminating the stabilizers used in the prior generation that braced it against the opposite vessel wall, reported Tamim Nazif, MD, of the Structural Heart & Valve Center at Columbia University Medical Center in New York City.

A trial is underway, with the 258-patient phase I portion having completed enrollment for randomization to the prior-generation device or no embolic protection, and the 275-patient phase II portion still enrolling for randomization to the third-generation device or no embolic protection. Results are expected early in 2019, Nazif said.

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