Transcatheter aortic “valve-in-valve” for degenerated bioprostheses: Choosing the right TAVI valve

Introduction

Aortic valve replacement (AVR) with cardiopulmonary bypass, cardioplegic arrest and aortic cross-clamping represents the treatment of choice for the treatment of aortic valve diseases and provides good operative outcomes and long-term results (1,2). Following standard international guidelines, patients over 65 years of age at surgery or younger patients with contraindications to the anticoagulation are candidates for the implantation of a bioprosthesis (3-5). Despite all attempts to decrease the incidence of leaflet calcification and structural failure, early structural valve degeneration (SVD) can occur. Redo valve surgery in the elderly with associated comorbidities is associated with a higher operative risk, increased hospital mortality, and increased complication rates (6). Transcatheter valve procedures through transapical, transfemoral and transaortic accesses can be performed in selected cases of degenerated aortic bioprostheses [“valve-in-valve” concept (VinV)] with surprisingly technical ease. Experienced centers employ this technique routinely with very good clinical results (7-16). Transcatheter aortic valve implantation (TAVI) prostheses routinely employed for VinV procedures are the balloon-expandable Edwards Sapien™ XT and the self-expandable Medtronic Corevalve®, whereas other CE-marked stent-valves are under evaluation. It is our experience that the Sapien™ XT valve seems to better adapt to commonly used bioprostheses during VinV procedure.

Technical aspects and results

Symptomatic patients with degenerated bioprostheses presenting with advanced age or severe comorbidities are good candidates for transcatheter VinV, whereas endocarditis remains a formal contraindication. Specific preoperative exams and cardiac imaging are not usually required, given that the size of the implantable TAVI-valve is pre-determined by the size of the pre-existing bioprosthesis. However, a risk of mismatch exists and one needs to take into consideration the real inner diameter of the bioprosthesis in order to implant the ideal Sapien™ XT valve (see Table 1): (I) the 23 mm Sapien™ valve implanted into a 21 mm size stented bioprosthesis is at risk for high trans-valvular gradients; (II) the 23 mm Sapien™ XT fits into a 23 mm and 25 mm bioprosthesis; (III) the 23 mm Sapien™ XT fits into the 27 mm Sorin Mitroflow™, whereas the 27 mm Trifecta™, Perimount™ and Hankock® require the implantation of a 26 mm Sapien™ XT.

During VinV procedures, angiography may not be necessary and the procedure can be performed under transesophageal echocardiographic and fluoroscopic control. Contrast is not required because the ring of the bioprosthesis is radiopaque and acts as a landmark. Regarding the positioning, the lower margin of the Sapien™ should remain 2-3 mm below the lower margin of the bioprosthesis in order to optimize the shape and the hemodynamic performances of the TAVI valve (17). The TAVI implantation follows the same sequence of steps for standard TAVI thereafter, with the exception that there is no need for a balloon valvuloplasty.

Concerning the results, published clinical data are very encouraging with a success rate of 100%, very low paravavular leak rates, and acceptable trans-valvular gradients as long as the pre-existing valve was 23 mm or larger. Patients with a degenerated 19 or 21 mm bioprosthesis have high residual trans-valvular peak gradients ranging from 30-40 mmHg (11,15,17). Thus, this option should be considered only for inoperable patients.

Conclusion

Results from aortic VinV series suggest that the technique produces very acceptable trans-valvular gradients in 23 mm and 25 mm degenerated bioprostheses, with absence of relevant leakage and a low rate of complications. Moreover, the aortic VinV is safe, does not require a specific preoperative cardiac imaging, does not require aortography and pre-ballooning, and can be performed in patients with chronic renal failure (low risk of postoperative kidney injury and low risk of embolization). In conclusion, the 23 mm Sapien™ XT seems to be the most useful TAVI valve because it fits within the majority of currently used bioprostheses (23 mm and the 25 mm diameter). We suggest implanting large bioprosthesis during first-time standard AVR in order to prevent size mismatch in case of future VinV procedures.

Acknowledgements

Disclosure: The author declares no conflicts of interest.

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