Transcatheter Aortic Valve Replacement in Pure Native Aortic Valve Regurgitation: Challenging Pathology Awaiting Specialized Devices

Patients with aortic incompetence frequently present with anatomical and pathological challenges such as elliptical dilated annulus, dilated aortic root, dilated ascending aorta, and with no calcification in the aortic cusps or annulus. Patients are commonly in graver clinical condition as a result of a long silent clinical course before overt congestive heart failure. All of the above make transcatheter therapies for native aortic valve regurgitation more challenging with poorer outcomes, escalating the risk of insufficient anchoring, prosthesis migration, and residual paravalvular leak compared with current transcatheter aortic valve replacement (TAVR) outcomes for aortic stenosis. There is a need for specialized TAVR devices to address this complex pathology. Surgical aortic valve replacement is the current treatment option and the gold standard for patients with aortic incompetence (AR). Currently, the specific off-label indication for TAVR in pure native AR could be a feasible and reasonable option, as a compassionate treatment is limited to inoperable patients and agreed on by the heart team.

Native Aortic Valve Disease Progression and Bioprosthetic Valve Degeneration in Patients with Transcatheter Aortic Valve Implantation

Background: There remain major uncertainties regarding disease activity within the retained native aortic valve as well as bioprosthetic valve durability following transcatheter aortic valve implantation (TAVI). We aimed to assess native aortic valve disease activity and bioprosthetic valve durability in patients with TAVI in comparison to subjects with bioprosthetic surgical aortic valve replacement (SAVR). Methods: In a multicenter cross-sectional observational cohort study, patients with TAVI or bioprosthetic SAVR underwent baseline echocardiography, CT angiography and 18 F-sodium fluoride ( 18 F-NaF) positron emission tomography (PET). Participants (n=47) were imaged once with 18 F-NaF PET/CT either at one-month (n=9, 19%), 2 years (n=22, 47%) or 5 years (16, 34%) after valve implantation. Subsequently patients underwent serial echocardiography to assess for changes in valve hemodynamic performance (change in peak aortic velocity) and evidence of structural valve dysfunction. Comparisons were made to matched patients with bioprosthetic SAVR (n=51) who had undergone the same imaging protocol. Results: In patients with TAVI, native aortic valves demonstrated 18 F-NaF uptake around the outside of the bioprostheses that showed a modest correlation with the time from TAVI (r=0.36, p=0.023). 18 F-NaF uptake in the bioprosthetic leaflets was comparable between the SAVR and TAVI groups (target-to-background ratio 1.3 [1.2-1.7] versus 1.3 [1.2-1.5] respectively, p=0.27). The frequencies of imaging evidence of bioprosthetic valve degeneration at baseline were similar on echocardiography (6% versus 8% respectively, p=0.78), CT (15% versus 14% respectively, p=0.87) and PET (15% versus 29% respectively, p=0.09). Baseline 18 F-NaF uptake was associated with subsequent change in peak aortic velocity for both TAVI (r=0.7, p<0.001) and SAVR (r=0.7, p<0.001). On multivariable analysis, 18 F-NaF uptake was the only predictor of peak velocity progression (p<0.001). Conclusions: In patients with TAVI, native aortic valves demonstrate evidence of ongoing active disease. Across imaging modalities, TAVI degeneration is of similar magnitude to bioprosthetic SAVR suggesting comparable mid-term durability. Clinical Trial Registration: URL: https://www.clinicaltrials.gov/ Unique Identifier: NCT02304276

Autograft Root Dilation After the Ross Procedure Is Not Benign

Autograft root dilation is common after the unsupported Ross procedure. In the absence of valvar incompetence, and with the perception that dissection is exceedingly rare, expectant management of autograft aneurysm is common practice. Autograft dissection may not be as rare as thought though, as at this point 7 case reports have accrued that describe autograft dissection requiring urgent operative intervention. All had a bicuspid native aortic valve. Bicuspid aortic valve has been shown to be associated with an intrinsic, histologically demonstrated pulmonary arteriopathy, possibly contributing to autograft root dilation and dissection. Autograft root dilation can no longer be regarded as benign, especially in patients with bicuspid aortic valve. Mounting evidence further validates the practice of externally supporting the Ross autograft. For patients who have had an unsupported Ross procedure, mounting evidence may support earlier intervention for autograft root dilation and aneurysm.

Calcification of bioprosthetic heart valves treated with ethylene glycol diglycidyl ether

Highlights. The morphology and elemental composition of calcium deposits formed in the tissues of epoxytreated aortic and mitral bioprostheses do not differ from those in the mineralized matrix of stenotic human aortic valve leaflets. Despite similar elemental composition of mineral deposits in the KemCor and UniLine bioprostheses, the morphology of these calcifications differs between bioprosthetic heart valve substitutes and, apparently, is associated with the specific structure of the fibrous matrix of the biological tissues that are used for their manufacturing.Aim. To analyze the morphology and elemental composition of mineral deposits formed in epoxy-treated aortic and mitral bioprosthetic heart valves made from xenoaortic or xenopericardial material and to compare the obtained findings with the data on calcified human aortic valve.Methods. Leaflets of the mitral and aortic bioprosthetic heart valves KemCor and UniLine (NeoKor, L Russia, Kemerovo) that were explanted due to their failure, as well as leaflets of the calcified native aortic valve were evaluated. The morphology of calcifications was studied by scanning electron microscopy using an S-3400N microscope (Hitachi, Japan). The elemental composition of calcium deposits was studied by electron probe microanalysis using Hitachi S-3400N microscope with energy dispersive spectrometer Bruker XFlash 4010 (Bruker, Germany).Results. Large calcifications located at the internal layers of samples were surrounded by collagen fibers commonly with evident signs of the onset of mineralization. Calcium deposits in the native aortic valve and xenoartic bioprostheses KemCor were located mainly at the spongy layer and had a loose structure, while dense lamellar deposits were found at the leaflets of pericardial bioprostheses UniLine. The elemental composition of calcium deposits showed the presence of Ca, P, O, Mg, and Na in the mineralized regions and the presence of S in the regions of low electron density. The calcium to phosphorus ratio (Ca:P) in the calcifications of the aortic valve leaflets was 1.81 (1.79-1.84; min - 1.48; max - 2.05), whereas the Ca:P ratios in the UniLine and KemCor bioprostheses were 1.78 (1.75-1.86; min - 1.52; max - 2.03) and 1.82 (1.81-1.88; min - 1.71; max - 2.06), respectively. There were no significant differences in the Ca:P ratios between calcifications in the study groups (p>0.05).Conclusion. Calcium deposits detected in epoxy-treated bioprostheses and human aortic valve appeared to be formed under dystrophic calcification. The morphology of calcifications in bioprostheses depended on the type of biological tissue. None correlations between the morphological structure of calcifications and the implantation position were found in bioprosthetic leaflets. The elemental composition of mineral deposits was similar in all study samples.